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{{Short description|Philosophical system originating from Thomas Aquinas}}
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{{Primary sources|date=September 2022}}{{Original research|date=September 2022}}
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{{Thomism}}
[[File:Thomas Aquinas in Stained Glass crop.jpg|thumb|[[Thomas Aquinas]] ({{circa|1225}}–1274)]]
{{Catholic philosophy}}
'''Thomism''' is the [[Philosophy|philosophical]] and [[Theology|theological]] school which arose as a legacy of the [[List of works by Thomas Aquinas|work]] and thought of [[Thomas Aquinas]] (1225–1274), the [[Dominican Order|Dominican]] philosopher, theologian, and [[Doctor of the church#Catholic Church|Doctor of the Church]].

In philosophy, Thomas's disputed questions and commentaries on [[Aristotle]] are perhaps his best-known works. In theology, his ''[[Summa Theologica]]'' is amongst the most influential documents in [[Medieval philosophy#Theology|medieval theology]] and continues to be the central point of reference for the philosophy and theology of the [[Catholic Church]]. In the 1914 [[motu proprio]] ''Doctoris Angelici'', [[Pope Pius X]] cautioned that the teachings of the Church cannot be understood without the basic philosophical underpinnings of Thomas's major theses:<ref>{{cite web |url=http://maritain.nd.edu/jmc/etext/doctoris.htm |title=Doctoris Angelici |access-date=2009-11-04 |url-status=live |archive-url=https://web.archive.org/web/20090831110620/http://maritain.nd.edu/jmc/etext/doctoris.htm |archive-date=31 August 2009}} Accessed 25 October 2012</ref> 

{{quote|The capital theses in the philosophy of St. Thomas are not to be placed in the category of opinions capable of being debated one way or another, but are to be considered as the foundations upon which the whole science of natural and divine things is based; if such principles are once removed or in any way impaired, it must necessarily follow that students of the sacred sciences will ultimately fail to perceive so much as the meaning of the words in which the dogmas of divine revelation are proposed by the magistracy of the Church.}}{{Scholasticism}}

== Overview ==
[[Thomas Aquinas]] held and practiced the principle that [[truth]] is to be accepted no matter where it is found. His doctrines drew from [[ancient Greek philosophy|Greek]], [[Roman philosophy|Roman]], [[Islamic philosophy|Islamic]] and [[Jewish philosophy|Jewish]] philosophers. Specifically, he was a [[Philosophical realism|realist]] (i.e. unlike [[Philosophical skepticism|skeptics]], he believed that the world can be known as it is).<ref>[https://www.newadvent.org/summa/1085.htm#article2 ''Summa'', I, Q.85, art.2.] {{webarchive|url=https://web.archive.org/web/20230405221811/https://www.newadvent.org/summa/1085.htm |date=5 April 2023 }} "Some have asserted that our intellectual faculties know only the impression made on them; as, for example, that sense is cognizant only of the impression made on its own organ. According to this theory, the intellect understands only its own impression, namely, the intelligible species which it has received, so that this species is what is understood. This is, however, manifestly false for two reasons [...]"</ref> He often affirmed [[Aristotle]]'s views with independent arguments, and largely followed [[Aristotelianism|Aristotelian]] terminology and [[metaphysics]]. He wrote comprehensive [[commentaries on Aristotle]], and respectfully referred to him simply as "the Philosopher".<ref>E.g., [http://www.newadvent.org/summa/1084.htm#article7 ''Summa Theologiæ'', Q.84, art.7.] {{webarchive|url=https://web.archive.org/web/20091029234148/http://www.newadvent.org/summa/1084.htm |date=29 October 2009 }}, where the ''sed contra'' is only a quote from Aristotle's ''[[De anima]]''.</ref>

<!--  -->He also adhered to some [[neoplatonism|neoplatonic]] principles, for example that "it is absolutely true that there is first something which is essentially being and essentially good, which we call God, [...] [and that] everything can be called good and a being, inasmuch as it [[Theory of Forms|''participates'' in it by way of a certain assimilation]]".<ref>{{cite web |url=http://www.newadvent.org/summa/1006.htm#article4 |title=''Summa'', I, Q.6, art.4 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111204142644/http://www.newadvent.org/summa/1006.htm#article4 |archive-date=4 December 2011}}</ref>

== Metaphysics ==
Aquinas says that the fundamental [[axiom]]s of [[ontology]] are the [[principle of non-contradiction]] and the [[principle of causality]]. Therefore, any [[being]] that does not contradict these two laws could theoretically exist,<ref>[http://www.op-stjoseph.org/Students/study/thomas/DeEnte&Essentia.htm ''De Ente et Essentia'', 67–68.] {{webarchive|url=https://web.archive.org/web/20091126104033/http://www.op-stjoseph.org/Students/study/thomas/DeEnte%26Essentia.htm |date=26 November 2009 }} "Although everyone admits the simplicity of the First Cause, some try to introduce a composition of matter and form in the intelligences and in souls... But this is not in agreement with what philosophers commonly say, because they call them substances separated from matter, and prove them to be without all matter."</ref> even if said being were [[incorporeal]].<ref>{{cite web |url=http://www.op-stjoseph.org/Students/study/thomas/ContraGentiles2.htm#91 |title=''Summa contra Gentiles'', II, chp. 91 |publisher=Op-stjoseph.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20090228235648/http://www.op-stjoseph.org/Students/study/thomas/ContraGentiles2.htm#91 |archive-date=28 February 2009}}</ref>

=== Predication ===
{{further|Univocity of being|Analogia entis}}
Aquinas noted three forms of descriptive language when [[Predicate (grammar)|predicating]]: univocal, [[analogy|analogical]], and [[Equivocation|equivocal]].<ref>{{cite book | author = Sproul, R.C. | author-link = R. C. Sproul | title = Renewing Your Mind: Basic Christian Beliefs You Need to Know | publisher = Baker Books | location = Grand Rapids, MI | year = 1998 | page = [https://archive.org/details/renewingyourmind0000spro/page/33 33] | isbn = 978-0-8010-5815-8 | url-access = registration | url = https://archive.org/details/renewingyourmind0000spro/page/33 }}</ref>
* '''Univocality''' is the use of a descriptor in the same sense when applied to two objects or groups of objects. For instance, when the word "milk" is applied both to milk produced by cows and by any other female mammal.
* '''Analogy''' occurs when a descriptor changes some but not all of its meaning. For example, the word "healthy" is analogical in that it applies both to a person or animal which enjoys good health and to some food or drink which promotes health.
* '''Equivocation''' is the complete change in meaning of the descriptor and is an [[informal fallacy]], for example when the word "bank" is applied to river banks and financial banks. Modern philosophers call it [[ambiguity]].

Further, the usage of "[[definition]]" that Aquinas gives is the [[genus]] of the being, plus a difference that sets it apart from the genus itself. For instance, the [[Aristotelianism|Aristotelian]] definition of "man" is "[[rational animal]]"; its genus being animal, and what sets apart man from other animals is his [[rationality]].<ref name="rationalanimal">{{cite web |url=http://www.op-stjoseph.org/Students/study/thomas/DeEnte&Essentia.htm |title=''De Ente et Essentia'', 37 |publisher=Op-stjoseph.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20091126104033/http://www.op-stjoseph.org/Students/study/thomas/DeEnte%26Essentia.htm |archive-date=26 November 2009}}</ref>

=== Being ===
{{See also|Being#Thomistic analogical predication of being}}
{{Quote|[E]xistence is twofold: one is essential existence or the '''[[Substance theory|substantial]]''' existence of a thing, for example man exists, and this is existence ''simpliciter''. The other is '''[[Accident (philosophy)|accidental]]''' existence, for example man is white, and this is existence ''secundum quid''.|[https://aquinas.cc/la/en/~DePrinNat.C1''De Principiis Naturæ'', C. 1]}}

In Thomist philosophy, the definition of a [[being]] is "that which is", a principle with two parts: "that which" refers to its ''[[quiddity]]'' (literally "whatness"), and "is" refers to its ''esse'' ([[Latin language|Latin]] "to be").<ref>[http://www.op-stjoseph.org/Students/study/thomas/DeEnte&Essentia.htm ''De Ente et Essentia'', 83.] {{webarchive|url=https://web.archive.org/web/20091126104033/http://www.op-stjoseph.org/Students/study/thomas/DeEnte%26Essentia.htm |date=26 November 2009 }} "And this is why substances of this sort are said by some to be composed of "that by which it is" and "that which is", or as Boethius says, of "that which is" and "existence.""</ref> ''Quiddity'' means an [[essence]], [[Theory of Forms|form]], or [[Nature (philosophy)|nature]] which may or may not exist; whereas ''esse'' refers to existence or reality. That is, a being is "an essence that exists."<ref name="definitionofbeing">[http://www.newadvent.org/summa/1003.htm#article4 ''Summa'', I, Q.3, art.4.] {{webarchive|url=https://web.archive.org/web/20111109160402/http://newadvent.org/summa/1003.htm |date=9 November 2011 }} "Therefore, if the existence of a thing differs from its essence, this existence must be caused either by some exterior agent or by its essential principles."</ref>

Being is divided in two ways: that which is ''in itself'' ([[Substance theory|substances]]), and that which is ''in another'' ([[Accident (philosophy)|accidents]]). Substances are things which exist ''per se'' or in their own right. Accidents are qualities that apply to other things, such as shape or color: "[A]ccidents must include in their definition a subject which is outside their genus."<ref>{{cite web |url=http://www.op-stjoseph.org/Students/study/thomas/DeEnte&Essentia.htm |title=''De Ente et Essentia'', 17 |publisher=Op-stjoseph.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20091126104033/http://www.op-stjoseph.org/Students/study/thomas/DeEnte%26Essentia.htm |archive-date=26 November 2009}}</ref> Because they only exist in other things, Aquinas holds that [[metaphysics]] is primarily the study of substances, as they are the primary mode of being.<ref>{{cite web |url=http://www.op-stjoseph.org/Students/study/thomas/DeEnte&Essentia.htm |title=''De Ente et Essentia'', 110 |publisher=Op-stjoseph.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20091126104033/http://www.op-stjoseph.org/Students/study/thomas/DeEnte%26Essentia.htm |archive-date=26 November 2009}} "And because accidents are not composed of matter and form, their genus cannot be taken from matter and their difference from form, as in the case of composed substances."</ref>

''[[The Catholic Encyclopedia]]'' pinpoints Aquinas' definition of ''quiddity'' as "that which is expressed by its definition."<ref>{{cite web |url=http://www.newadvent.org/cathen/05543b.htm |title=Aveling, Francis. "Essence and Existence." The Catholic Encyclopedia. Vol. 5. New York: Robert Appleton Company, 1909. 4 Nov. 2009 |publisher=Newadvent.org |date=1 May 1909 |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111011221713/http://www.newadvent.org/cathen/05543b.htm |archive-date=11 October 2011}}</ref> The ''quiddity'' or [[Theory of Forms|form]] of a thing is what makes the object what it is: "[T]hrough the form, which is the [[Potentiality and actuality|actuality]] of matter, matter becomes something actual and something individual",<ref>{{cite web |url=http://www.op-stjoseph.org/Students/study/thomas/DeEnte&Essentia.htm |title=''De Ente et Essentia'', 18 |publisher=Op-stjoseph.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20091126104033/http://www.op-stjoseph.org/Students/study/thomas/DeEnte%26Essentia.htm |archive-date=26 November 2009}}</ref> and also, "the form causes matter to be."<ref>[http://www.newadvent.org/summa/1075.htm#article5 ''Summa'', I, Q.75, art.5.] {{webarchive|url=https://web.archive.org/web/20120119083516/http://www.newadvent.org/summa/1075.htm |date=19 January 2012 }} The meaning of this sentence can be altered depending on how the Latin word used in this sentence, "materiæ", is translated into English. An alternate rendering of this sentence is "The form causes matter ''to be what it is''.</ref> Thus, it consists of two parts: "prime matter" (matter without form),<ref>{{cite web |url=http://dhspriory.org/thomas/DeEnte&Essentia.htm |title=''De Ente et Essentia'', 40 |publisher=Dhspriory.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111219234241/http://dhspriory.org/thomas/DeEnte%26Essentia.htm |archive-date=19 December 2011}}</ref> and [[substantial form]], which is what causes a substance to have its characteristics. For instance, an animal can be said to be a being whose matter is its body, and whose [[Soul#Thomas Aquinas|soul]]<ref name="soul">The Aristotelian and Thomist definition of the "soul" does not refer to spirit, but is perhaps better translated as "life force." Hence, plants have souls in the sense that they are living beings. The human soul is unique in that it has consciousness. Cf. ''[[De anima]]'', Bk. I.</ref> is its substantial form.<ref>{{cite web |url=http://www.op-stjoseph.org/Students/study/thomas/DeEnte&Essentia.htm |title=''De Ente et Essentia'', 14 |publisher=Op-stjoseph.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20091126104033/http://www.op-stjoseph.org/Students/study/thomas/DeEnte%26Essentia.htm |archive-date=26 November 2009}}</ref><ref>[http://www.op-stjoseph.org/Students/study/thomas/DePrincNaturae.htm ''De Principiis Naturæ'', 5.] {{webarchive|url=https://web.archive.org/web/20090916155648/http://www.op-stjoseph.org/Students/study/thomas/DePrincNaturae.htm |date=16 September 2009 }} "But, just as everything which is in potency can be called matter, so also everything from which something has existence whether that existence be substantial or accidental, can be called form; for example man, since he is white in potency, becomes actually white through whiteness, and sperm, since it is man in potency, becomes actually man through the soul."</ref> Together, these constitute its ''quiddity''/essence.

All real things have the [[Transcendentals|transcendental properties of being]]: [[wikt:unity|oneness]], [[truth]], goodness (that is, all things have a [[final cause]] and therefore a [[Teleology|purpose]]), etc.<ref>{{cite web |url=http://www.op-stjoseph.org/Students/study/thomas/QDdeVer1.htm |title=''De veritate'', Q.1 |publisher=Op-stjoseph.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20090424063600/http://www.op-stjoseph.org/Students/study/thomas/QDdeVer1.htm |archive-date=24 April 2009}}</ref>

=== Causality ===
Aristotle categorized causality into [[Four causes|four subsets]] in the ''[[Metaphysics (Aristotle)|Metaphysics]]'', which is an integral part of Thomism:

{{Quote|"In one sense the term cause means (a) that from which, as something intrinsic, a thing comes to be, as the bronze of a statue and the silver of a goblet, and the genera of these. In another sense it means (b) the form and pattern of a thing, i.e., the intelligible expression of the ''quiddity'' and its genera (for example, the ratio of 2:1 and number in general are the cause of an octave chord) and the parts which are included in the intelligible expression. Again, (c) that from which the first beginning of change or of rest comes is a cause; for example, an adviser is a cause, and a father is the cause of a child, and in general a maker is a cause of the thing made, and a changer a cause of the thing changed. Further, a thing is a cause (d) inasmuch as it is an end, i.e., that for the sake of which something is done; for example, health is the cause of walking. For if we are asked why someone took a walk, we answer, "in order to be healthy"; and in saying this we think we have given the cause. And whatever occurs on the way to the end under the motion of something else is also a cause. For example, reducing, purging, drugs and instruments are causes of health; for all of these exist for the sake of the end, although they differ from each other inasmuch as some are instruments and others are processes."|[http://dhspriory.org/thomas/Metaphysics5.htm#2 Metaphysics 1013a, trans. John P. Rowan, Chicago, 1961]}}

:* (a) refers to the '''material cause''', what a being's matter consists of (if applicable).
:* (b) refers to the '''formal cause''', what a being's essence is.
:* (c) refers to the '''efficient cause''', what brings about the beginning of, or change to, a being.
:* (d) refers to the '''final cause''', what a being's purpose is.

Unlike many [[ancient Greek philosophy|ancient Greeks]]{{who?|date=October 2022}}, who thought that an [[infinite regress]] of causality is possible (and thus held that the universe is uncaused), Aquinas argues that an infinite chain never accomplishes its objective and is thus impossible.<ref name=":1" /><ref name="Summa, I, Q.44, art.1">{{cite web |url=http://www.newadvent.org/summa/1044.htm#article1 |title=''Summa'', I, Q.44, art.1 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111105100607/http://www.newadvent.org/summa/1044.htm#article1 |archive-date=5 November 2011}}</ref> Hence, a [[first cause]] is necessary for the existence of anything to be possible. Further, the First Cause must continuously be in action (similar to how there must always be a first chain in a [[Chain-link fencing|chain link]]), otherwise the series collapses:<ref>{{cite web |url=http://dhspriory.org/thomas/Metaphysics5.htm |title=St. Thomas Aquinas's commentary on the ''Metaphysics'', Bk. V, 1015a 20-1015b 15, §840 |publisher=Dhspriory.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111119193820/http://dhspriory.org/thomas/Metaphysics5.htm |archive-date=19 November 2011}}</ref>

{{Quote|[[Aristotle|The Philosopher]] says ([http://dhspriory.org/thomas/Metaphysics2.htm#4 ''Metaph''. ii, 2]) that "to suppose a thing to be indefinite is to deny that it is good." But the good is that which has the nature of an end. Therefore it is contrary to the nature of an end to proceed indefinitely. Therefore it is necessary to fix one last end.|[http://www.newadvent.org/summa/2001.htm#article4 ''Summa'', II-I, Q.1, art.4.]}}

Thus, both Aristotle and Aquinas conclude that there must be an uncaused Primary Mover,<ref name="Summa, I, Q.44, art.1"/><ref>{{cite web |url=http://dhspriory.org/thomas/Metaphysics2.htm#3 |title=St. Thomas Aquinas's commentary on the Metaphysics, Bk. II, 994a 11-994b 9 |publisher=Dhspriory.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111127020714/http://dhspriory.org/thomas/Metaphysics2.htm#3 |archive-date=27 November 2011}}</ref><ref>{{cite web|url=http://dhspriory.org/thomas/ContraGentiles2.htm#15|title=''Summa contra Gentiles'', II, chp.15|website=dhspriory.org|url-status=live|archive-url=https://web.archive.org/web/20100903045031/http://dhspriory.org/thomas/ContraGentiles2.htm#15|archive-date=3 September 2010}}</ref><ref name=":1">[http://www.newadvent.org/summa/1002.htm#article3 ''Summa'', I, Q.2, art.3.] {{webarchive|url=https://web.archive.org/web/20130428053715/http://www.newadvent.org/summa/1002.htm |date=28 April 2013 }} "The third way is taken from possibility and necessity, and runs thus..."</ref> because an infinite regress is impossible.<ref>{{cite web |url=http://www.newadvent.org/summa/2001.htm#article4 |title=''Summa'', II-I, Q.1, art.4 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111105095827/http://www.newadvent.org/summa/2001.htm#article4 |archive-date=5 November 2011}}</ref>

However, the First Cause does not necessarily have to be temporally the first. Thus, the question of whether or not the universe can be imagined as eternal was fiercely debated in the [[Middle Ages]]. The [[Condemnations of 1210–1277|University of Paris's condemnation of 1270]] denounced the belief that the world is eternal. Aquinas' intellectual rival, [[Bonaventure]], held that the [[Temporal finitism|temporality]] of the universe is demonstrable by reason.<ref>Davis, Richard. "Bonaventure and the Arguments for the Impossibility of an Infinite Temporal Regression", ''American Catholic Philosophical Quarterly'' 70, no. 3 (Summer 1996): pp. 361–380. Poiesis: Philosophy Online, EBSCOhost (Retrieved 13 April 2010): 380.</ref> Aquinas' position was that the temporality of the world is an article of faith, and not demonstrable by reason; one could reasonably conclude either that the universe is temporal or that it is eternal.<ref>{{cite web |url=http://www.newadvent.org/summa/1046.htm#article2 |title=''Summa'', I, Q.46, art.2 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109160407/http://newadvent.org/summa/1046.htm#article2 |archive-date=9 November 2011}}</ref><ref>{{cite web |url=http://dhspriory.org/thomas/DeEternitateMundi.htm |title=''De aeternitate mundi'' |publisher=Dhspriory.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111204111751/http://dhspriory.org/thomas/DeEternitateMundi.htm |archive-date=4 December 2011}}</ref>

=== Goodness ===
As per the ''[[Nicomachean Ethics]]'' of [[Aristotle]],<ref>{{cite web |url=http://dhspriory.org/thomas/Ethics1.htm |title=''Nicomachean Ethics'', Bk. I, Chp. I, 1094a4 |publisher=Dhspriory.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111001211100/http://dhspriory.org/thomas/Ethics1.htm |archive-date=1 October 2011}}</ref> Aquinas defines "[[Value (ethics)|the good]]" as what all things strive for. E.g., a cutting knife is said to be good if it is effective at its function, cutting. As all things have a function/[[final cause]], all real things are good. Consequently, [[evil]] is nothing but ''[[privatio boni]]'', or "lack of good", as [[Augustine of Hippo]] defined it.<ref>[[Augustine of Hippo]]. [http://www.newadvent.org/fathers/1302.htm ''Enchridion'', chp. 11.] {{webarchive|url=https://web.archive.org/web/20100109103333/http://www.newadvent.org/fathers/1302.htm |date=9 January 2010 }}</ref>

{{Quote|[[Pseudo-Dionysius|Dionysius]] says (Div. Nom. iv), 'Evil is neither a being nor a good.' I answer that, one opposite is known through the other, as darkness is known through light. Hence also what evil is must be known from the nature of good. Now, we have said above that good is everything appetible; and thus, since every nature desires its own being and its own perfection, it must be said also that the being and the perfection of any nature is good. Hence it cannot be that evil signifies being, or any form or nature. Therefore it must be that by the name of evil is signified the absence of good. And this is what is meant by saying that 'evil is neither a being nor a good.' For since being, as such, is good, the absence of one implies the absence of the other.|[http://www.newadvent.org/summa/1048.htm#article1 ''Summa'', I, Q.48, art.1.]}}

Commentating on the aforementioned, Aquinas says that "there is no problem from the fact that some men desire evil. For they desire evil only under the aspect of good, that is, insofar as they think it good. Hence their intention primarily aims at the good and only incidentally touches on the evil."<ref>{{cite web |url=http://dhspriory.org/thomas/Ethics1.htm#1 |title=St. Thomas Aquinas's commentary on the ''Nicomachean Ethics'', Bk. I, Lec. I, §10 |publisher=Dhspriory.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111001211100/http://dhspriory.org/thomas/Ethics1.htm#1 |archive-date=1 October 2011}}</ref>

As God is the ultimate end of all things,<ref>{{cite web |url=http://dhspriory.org/thomas/ContraGentiles3a.htm#18 |title=''Summa Contra Gentiles'', III, Q.18 |publisher=Dhspriory.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111007222742/http://dhspriory.org/thomas/ContraGentiles3a.htm#18 |archive-date=7 October 2011}}</ref> God is by essence goodness itself.<ref name="Godisgood">{{cite web |url=http://www.newadvent.org/summa/1006.htm |title=''Summa'', I., Q.6., art.2 & 3 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111204142644/http://www.newadvent.org/summa/1006.htm |archive-date=4 December 2011}}</ref> Furthermore, since love is "to wish the good of another",<ref>{{cite web |url=http://www.newadvent.org/summa/2026.htm#article4 |title=''Summa'', II-I, Q.26, art.4 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109213721/http://newadvent.org/summa/2026.htm#article4 |archive-date=9 November 2011}}</ref> true love in Thomism is to lead another to God. Hence why [[John the Evangelist]] says, "Whoever is without love does not know God, for God is love."<ref>{{cite web |url=http://www.usccb.org/nab/bible/1john/1john4.htm |title=1 John 4:8 |publisher=Usccb.org |date=13 March 2011 |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20110731155725/http://www.usccb.org/nab/bible/1john/1john4.htm |archive-date=31 July 2011}}</ref><ref name="God is love">{{cite web |url=http://www.newadvent.org/summa/1020.htm#article1 |title=''Summa'', I, Q.20, art.1 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111115172453/http://www.newadvent.org/summa/1020.htm#article1 |archive-date=15 November 2011}}</ref>

=== Existence of God ===
{{Main|Quinquae viae}}
Thomas Aquinas holds that the [[existence of God]] can be [[Posterior_Analytics|demonstrated]] by reason,<ref>{{cite web |url=http://www.newadvent.org/summa/1002.htm |title=''Summa'', I, Q.2 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20130428053715/http://www.newadvent.org/summa/1002.htm |archive-date=28 April 2013}}</ref> a view that is taught by the Catholic Church.<ref>''[[Catechism of the Catholic Church]]'', [https://www.vatican.va/archive/catechism/p1s1c1.htm CCC 34.] {{webarchive|url=https://web.archive.org/web/20090926223727/https://www.vatican.va/archive/catechism/p1s1c1.htm |date=26 September 2009 }}</ref> The ''quinque viae'' (Latin: '''five ways''') found in the ''[[Summa Theologica]]'' ([http://www.newadvent.org/summa/1002.htm#article3 I, Q.2, art.3]) are five possible ways of demonstrating the existence of God,<ref>Aquinas offers more metaphysical explanations for the existence of God in ''[http://www.op-stjoseph.org/Students/study/thomas/DeEnte&Essentia.htm De Ente et Essentia] {{webarchive|url=https://web.archive.org/web/20091126104033/http://www.op-stjoseph.org/Students/study/thomas/DeEnte%26Essentia.htm |date=26 November 2009 }}'' and elsewhere, though the ''Quinquae viae'' are the most well-known and most commonly analyzed among these.</ref> which today are categorized as:
: 1. ''Argumentum ex motu'', or the argument of the [[unmoved mover]];
: 2. ''Argumentum ex ratione causae efficientis'', or the argument of the [[first cause]];
: 3. ''Argumentum ex contingentia'', or the [[Necessary being|argument from contingency]];
: 4. ''Argumentum ex gradu'', or the [[argument from degree]]; and
: 5. ''Argumentum ex fine'', or the [[teleological argument]].
Despite this, Aquinas also thought that [[sacred mysteries]] such as [[the Trinity]] could only be obtained through [[revelation]]; though these truths cannot contradict reason:

{{Quote|The existence of God and other like truths about God, which can be known by natural reason, are not articles of faith, but are preambles to the articles; for faith presupposes natural knowledge, even as grace presupposes nature, and perfection supposes something that can be perfected. Nevertheless, there is nothing to prevent a man, who cannot grasp a proof, accepting, as a matter of faith, something which in itself is capable of being scientifically known and demonstrated.|[http://www.newadvent.org/summa/1002.htm#article2 ''Summa'', I, Q.2, art.2.]}}

Aquinas responds to the [[problem of evil]] by saying that God allows evil to exist so that good may come of it<ref>[http://dhspriory.org/thomas/ContraGentiles3a.htm#10 ''Summa Contra Gentiles'', Bk. III, Q.10.] {{webarchive|url=https://web.archive.org/web/20111007222742/http://dhspriory.org/thomas/ContraGentiles3a.htm |date=7 October 2011 }} "Thus, it is... that evil is only caused by good accidentally."</ref> (for goodness done out of free will is superior than goodness done from biological imperative), but does not personally cause evil Himself.<ref>{{cite web |url=http://www.newadvent.org/summa/1049.htm#article2 |title=''Summa'', I, Q.49, art.2 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109155603/http://newadvent.org/summa/1049.htm#article2 |archive-date=9 November 2011}}</ref>

=== View of God ===
{{further|Analogia entis}}
Aquinas articulated and defended, both as a philosopher and a theologian, the orthodox Christian [[God in Christianity|view of God]]. God is the sole being whose [[existence]] is the same as His [[essence]]: "what subsists in God is His existence."<ref>{{cite web |url=http://www.newadvent.org/summa/1003.htm |title=''Summa'', I, Q.3, art.4 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109160402/http://newadvent.org/summa/1003.htm |archive-date=9 November 2011}}</ref> (Hence why God names himself "[[I Am that I Am]]" in [http://www.newadvent.org/bible/exo003.htm Exodus 3:14].<ref>{{cite web |url=http://www.newadvent.org/summa/1013.htm#article11 |title=''Summa'', I, Q.13, art.11 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111120065531/http://www.newadvent.org/summa/1013.htm#article11 |archive-date=20 November 2011}}</ref>) Consequently, God cannot be a body (that is, He cannot be composed of [[matter]]),<ref>{{cite web |url=http://www.newadvent.org/summa/1003.htm#article1 |title=''Summa'', I, Q.13, art. 1 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109160402/http://newadvent.org/summa/1003.htm#article1 |archive-date=9 November 2011}}</ref> He cannot have any [[Accident (philosophy)|accidents]],<ref>{{cite web |url=http://www.newadvent.org/summa/1003.htm#article6 |title=''Summa'', I, Q.13, art. 6 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109160402/http://newadvent.org/summa/1003.htm#article6 |archive-date=9 November 2011}}</ref> and He must be [[Divine simplicity|simple]] (that is, not separated into parts; [[the Trinity]] is one [[Substance theory|substance]] in three persons).<ref>{{cite web |url=http://www.newadvent.org/summa/1003.htm#article7 |title=''Summa'', I, Q.13, art. 7 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109160402/http://newadvent.org/summa/1003.htm#article7 |archive-date=9 November 2011}}</ref> Further, He is [[Good and evil|goodness]] itself,<ref name="Godisgood" /> [[Perfection|perfect]],<ref>{{cite web |url=http://www.newadvent.org/summa/1004.htm |title=''Summa'', I., Q.4 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109155637/http://newadvent.org/summa/1004.htm |archive-date=9 November 2011}}</ref> [[Infinity|infinite]],<ref>{{cite web |url=http://www.newadvent.org/summa/1007.htm |title=''Summa'', I., Q.7 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109163652/http://newadvent.org/summa/1007.htm |archive-date=9 November 2011}}</ref> [[omnipotent]],<ref>{{cite web |url=http://www.newadvent.org/summa/1025.htm#article3 |title=''Summa'', I., Q.25, art.3 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111121213839/http://www.newadvent.org/summa/1025.htm#article3 |archive-date=21 November 2011}}</ref> omniscient,<ref name="omniscience" /> happiness itself,<ref name="Godishappiness">[http://www.newadvent.org/summa/2003.htm#article1 ''Summa'', II-I, Q.3, art.1.] {{webarchive|url=https://web.archive.org/web/20130312035235/http://www.newadvent.org/summa/2003.htm |date=12 March 2013 }} "God is happiness by His Essence."</ref> knowledge itself,<ref name="Godisknowledge" /> [[Agape|love]] itself,<ref name="God is love" /> [[omnipresent]],<ref>{{cite web |url=http://www.newadvent.org/summa/1008.htm |title=''Summa'', I., Q.8 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109163509/http://newadvent.org/summa/1008.htm |archive-date=9 November 2011}}</ref> [[Immutability (theology)|immutable]],<ref>{{cite web |url=http://www.newadvent.org/summa/1009.htm |title=''Summa'', I., Q.9 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109161542/http://newadvent.org/summa/1009.htm |archive-date=9 November 2011}}</ref> and eternal.<ref>{{cite web |url=http://www.newadvent.org/summa/1010.htm#article2 |title=''Summa'', I., Q.10, art.2 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111128084320/http://www.newadvent.org/summa/1010.htm#article2 |archive-date=28 November 2011}}</ref> Summing up these properties, Aquinas offers the term ''[[actus purus]]'' (Latin: "pure actuality").

Aquinas held that not only does God have [[knowledge]] of everything,<ref name="omniscience">{{cite web |url=http://www.newadvent.org/summa/1014.htm |title=''Summa'', I, Q.14, arts. 5, 6, & 9 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109162047/http://newadvent.org/summa/1014.htm |archive-date=9 November 2011}}</ref> but that God has "the most perfect knowledge", and that it is also true to say that God "is" His understanding.<ref name="Godisknowledge">{{cite web |url=http://www.newadvent.org/summa/1014.htm |title=''Summa'', I, Q.14, art. 4 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109162047/http://newadvent.org/summa/1014.htm |archive-date=9 November 2011}}</ref>

Aquinas also understands God as the transcendent cause of the universe, the "first Cause of all things, exceeding all things caused by Him", the source of all creaturely being and the cause of every other cause.<ref>Summa Theologiae I, Q. 12, art. 12.</ref> Consequently, God's causality is not like the causality of any other causes (all other causes are "secondary causes"), because He is the [[Transcendence_(philosophy)|transcendent source]] of all being, causing and sustaining every other existing thing at every instant. Consequently, God's causality is never in competition with the causality of creatures; rather, God even causes some things through the causality of creatures.<ref>Summa Contra Gentiles III, chap. 17.</ref>

Aquinas was an advocate of the "analogical way", which says that because God is infinite, people can only speak of God by [[analogy]], for some of the aspects of the divine nature are hidden (''[[Deus absconditus]]'') and others revealed (''[[Deus_revelatus_(Christian_theology)|Deus revelatus]]'') to finite human minds. Thomist philosophy holds that we can know ''about'' God through his creation (general revelation), but only in an analogous manner.<ref>[http://www.op-stjoseph.org/Students/study/thomas/ContraGentiles1.htm#30 ''Summa contra Gentiles'', Bk. I, chp. 30.] {{webarchive|url=https://web.archive.org/web/20090228055614/http://www.op-stjoseph.org/Students/study/thomas/ContraGentiles1.htm |date=28 February 2009 }} "For we cannot grasp what God is, but only what He is not and how other things are related to Him, as is clear from what we said above."</ref> For instance, we can speak of God's goodness only by understanding that goodness as applied to humans is similar to, but not identical with, the goodness of God. Further, he argues that [[sacred scripture]] employs [[figurative language]]: "Now it is natural to man to attain to intellectual truths through sensible objects, because all our knowledge originates from sense. Hence in Holy Writ, spiritual truths are fittingly taught under the ''likeness'' of material things."<ref>{{cite web |url=http://www.newadvent.org/summa/1001.htm#article9 |title=''Summa'', I, Q.1, art.9 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111123045429/http://www.newadvent.org/summa/1001.htm#article9 |archive-date=23 November 2011}}</ref>

In order to demonstrate God's creative power, Aquinas says: "If a being participates, to a certain degree, in an 'accident,' this accidental property must have been communicated to it by a cause which possesses it essentially. Thus iron becomes incandescent by the action of fire. Now, God is His own power which subsists by itself. The being which subsists by itself is necessarily one."<ref name="Summa, I, Q.44, art.1"/>

== Anthropology ==
[[File:SummaTheologiae.jpg|thumb|''[[Summa Theologiæ]]'', Pars secunda, prima pars. (copy by Peter Schöffer, 1471)]]
In addition to agreeing with the [[Aristotelianism|Aristotelian]] definition of man as "the [[rational animal]]",<ref name="rationalanimal" /> Aquinas also held various other beliefs about the [[Substance theory|substance]] of man. For instance, as the [[essence]] ([[Nature (philosophy)|nature]]) of all men are the same,<ref>[http://www.op-stjoseph.org/Students/study/thomas/DeEnte&Essentia.htm ''De Ente et Essentia'', 24.] {{webarchive|url=https://web.archive.org/web/20091126104033/http://www.op-stjoseph.org/Students/study/thomas/DeEnte%26Essentia.htm |date=26 November 2009 }} "It is clear, therefore, that the essence of man and the essence of [[Socrates]] do not differ, except as the non-designated from the designated. Whence [[Averroes|the Commentator]] says in his considerations on the seventh book of the ''[[Metaphysics (Aristotle)|Metaphysics]]'' that "Socrates is nothing other than animality and rationality, which are his ''[[quiddity]]''.""</ref> and the definition of being is "an essence that exists",<ref name="definitionofbeing" /> humans that are real therefore only differ by their [[Category of being|specific qualities]]. More generally speaking, all beings of the same [[genus]] have the same essence, and so long as they exist, only differ by [[accident (philosophy)|accidents]] and [[substantial form]].<ref>[http://www.op-stjoseph.org/Students/study/thomas/DeEnte&Essentia.htm ''De Ente et Essentia'', 33.] {{webarchive|url=https://web.archive.org/web/20091126104033/http://www.op-stjoseph.org/Students/study/thomas/DeEnte%26Essentia.htm |date=26 November 2009 }} "The difference, on the contrary, is a name taken from a determinate form, and taken in a determinate way, i.e. as not including a determinate matter in its meaning. This is clear, for example, when we say animated, i.e., that which has a soul; for what it is, whether a body or something other, is not expressed. Whence [[Avicenna|Ibn Sīnā]] says that the genus is not understood in the difference as a part of its essence, but only as something outside its essence, as the subject also is understood in its properties. And this is why the genus is not predicated essentially of the difference, as the Philosopher says in the third book of the Metaphysics and in the fourth book of the Topics, but only in the way in which a subject is predicated of its property."</ref>

=== Soul ===

Thomists define the soul as the substantial form of living beings.<ref>[http://dhspriory.org/thomas/DeAnima.htm St. Thomas Aquinas's commentary on ''De anima'', Bk. I, 402a1–403b2, §1.] {{webarchive|url=https://web.archive.org/web/20100404042737/http://dhspriory.org/thomas/DeAnima.htm |date=4 April 2010 }} "Now living beings taken all together form a certain class of being; hence in studying them the first thing to do is to consider what living things have in common, and afterwards what each has peculiar to itself. What they have in common is a life-principle or soul; in this they are all alike. In conveying knowledge, therefore, about living things one must first convey it about the soul as that which is common to them all. Thus when Aristotle sets out to treat of living things, he begins with the soul; after which, in subsequent books, he defines the properties of particular living beings."</ref> Thus, plants have "vegetative souls", animals have "sensitive souls",<ref name="soul" /> while human beings alone have "intellectual" – rational and immortal – souls.<ref>{{cite web |url=http://www.newadvent.org/summa/1075.htm#article6 |title=''Summa'', I, Q.75, art.6 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20120119083516/http://www.newadvent.org/summa/1075.htm#article6 |archive-date=19 January 2012}}</ref>

{{Quote|For Aristotle, the soul is one, but endowed with five groups of faculties (''dunámeis''): (1) the "vegetative" faculty (''threptikón''), concerned with the maintenance and development of organic life; (2) the appetite (''oretikón''), or the tendency to any good; (3) the faculty of sense perception (''aisthetikón''); (4) the "locomotive" faculty (''kinetikón''), which presides over the various bodily movements; and (5) reason (''dianoetikón''). The [[Scholasticism|Scholastics]] generally follow Aristotle's classification. For them body and soul are united in one complete substance. The soul is the ''forma substantialis'', the vital principle, the source of all activities. Hence their science of the soul deals with functions which nowadays belong to the provinces of biology and physiology. [...] The nature of the mind and its relations to the organism are questions that belong to philosophy or metaphysics.|[http://www.newadvent.org/cathen/05749a.htm Dubray, C. (1909). Faculties of the Soul. In ''The Catholic Encyclopedia''. New York: Robert Appleton Company. Retrieved May 29, 2010 from New Advent.]}}

The appetite of man has two parts, rational and irrational. The rational part is called the will, and the irrational part is called passion.

=== Ethics ===
Aquinas affirms Aristotle's definition of happiness as "an operation according to perfect [[virtue]]",<ref>{{cite web |url=http://www.newadvent.org/summa/2003.htm#article2 |title=''Summa'', II-I, Q.3, art.2 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20120109063700/http://www.newadvent.org/summa/2003.htm#article2 |archive-date=9 January 2012}}</ref><ref>[http://www.op-stjoseph.org/Students/study/thomas/Ethics1.htm#10 St. Thomas Aquinas's commentary on ''Nicomachean Ethics'', Lec. 10, §130.] {{webarchive|url=https://web.archive.org/web/20150924060713/http://www.op-stjoseph.org/Students/study/thomas/Ethics1.htm |date=24 September 2015 }} Aquinas further says that "it is clear that happiness is a virtue-oriented activity proper to man in a complete life."</ref> and that "happiness is called man's supreme good, because it is the attainment or enjoyment of the supreme good."<ref>{{cite web |url=http://www.newadvent.org/summa/2003.htm#article1 |title=''Summa'', II-I, Q.3, art.1 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20120109063700/http://www.newadvent.org/summa/2003.htm#article1 |archive-date=9 January 2012}}</ref> Aquinas defines virtue as a good habit, which is a good quality of a person demonstrated by his actions and reactions over a substantial period of time.<ref>{{cite book |last1=Porter |first1=Jean |title=The Recovery of Virtue |date=1994 |publisher=Society for Promoting Christian Knowledge |location=London |pages=109–110}}</ref> He writes:

{{Quote|As we have said above (Article 1), virtue implies a perfection of power: wherefore the virtue of a thing is fixed by the limit of its power (De Coelo i). Now the limit of any power must needs be good: for all evil implies defect; wherefore Dionysius says (Div. Hom. ii) that every evil is a weakness. And for this reason the virtue of a thing must be regarded in reference to good. Therefore human virtue which is an operative habit, is a good habit, productive of good works.|[http://www.newadvent.org/summa/2055.htm#article3 ''Summa'', I-II, Q.55, art.3.]}}

Aquinas ascertained the [[cardinal virtues]] to be [[prudence]], [[Temperance (virtue)|temperance]], [[justice]], and [[Cardinal virtues|fortitude]]. The cardinal virtues are natural and revealed in nature, and they are binding on everyone. There are, however, three [[theological virtues]]: [[faith]], [[hope]], and [[Charity (virtue)|charity]] (which is used interchangeably with love in the sense of ''[[agape]]''). These are [[supernatural]] and are distinct from other virtues in their object, namely, God.<ref>{{cite web |url=http://www.newadvent.org/summa/2062.htm#article2 |title=''Summa'', II-I, Q.62, art.2 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109214542/http://newadvent.org/summa/2062.htm#article2 |archive-date=9 November 2011}}</ref>

In accordance with [[Roman Catholic theology]], Aquinas argues that humans can neither wish nor do [[Good and evil|good]] without [[Grace in Christianity#Roman Catholicism|divine grace]].<ref>{{cite web |url=http://www.newadvent.org/summa/2109.htm#article2 |title=''Summa'', II-I, Q.109, art.2 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111113214919/http://www.newadvent.org/summa/2109.htm#article2 |archive-date=13 November 2011}}</ref> However, "doing good" here refers to doing good per se: man ''can'' do, moved by God even then but "only" in the sense in which even his nature depends on God's moving, things that happen to be good in some respect, and are not sinful, though if he has not grace, it will be without merit, and he will not succeed in it all the time. Therefore, happiness is attained through the perseverance of virtue given by the Grace of God,<ref>{{cite web |url=http://www.newadvent.org/summa/2109.htm#article10 |title=''Summa'', II-I, Q. 109, art.10 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111113214919/http://www.newadvent.org/summa/2109.htm#article10 |archive-date=13 November 2011}}</ref> which is not fully attained on earth;<ref>[http://www.newadvent.org/summa/2005.htm#article3 ''Summa'', II-I, Q.5, art.3.] {{webarchive|url=https://web.archive.org/web/20121021152708/http://www.newadvent.org/summa/2005.htm |date=21 October 2012 }} "First, from the general notion of happiness. For since happiness is a "perfect and sufficient good", it excludes every evil, and fulfils every desire. But in this life every evil cannot be excluded."</ref> only at the [[beatific vision]].<ref>[http://www.newadvent.org/summa/2005.htm#article1 ''Summa'', II-I, Q.5, art.1.] {{webarchive|url=https://web.archive.org/web/20121021152708/http://www.newadvent.org/summa/2005.htm |date=21 October 2012 }} "Happiness is the attainment of the Perfect Good... And therefore man can attain Happiness. This can be proved again from the fact that man is capable of seeing God, [which] man's perfect Happiness consists."</ref><ref>{{cite web |url=http://www.newadvent.org/summa/5093.htm#article1 |title=''Summa'', supp., Q.93, art.1 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111115002919/http://www.newadvent.org/summa/5093.htm#article1 |archive-date=15 November 2011}}</ref> Notably, man cannot attain true happiness without God.<ref name="Godishappiness" /><ref>{{cite web |url=http://www.newadvent.org/summa/2005.htm#article5 |title=''Summa'', II-I, Q.5, art.5 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109213956/http://newadvent.org/summa/2005.htm#article5 |archive-date=9 November 2011}}</ref>

Regarding [[emotion]] (used synonymously with the word "passion" in this context), which, following [[John Damascene]],<ref>{{cite web |url=http://www.newadvent.org/summa/2022.htm#article3 |title=''Summa'', II-I, Q.22, art.3 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109221323/http://newadvent.org/summa/2022.htm#article3 |archive-date=9 November 2011}}</ref> Aquinas defines as "a movement of the sensitive appetite when we imagine good or evil", Thomism repudiates both the [[Epicurean]] view that happiness consists in [[pleasure]] (sensual experiences that invoke positive emotion),<ref>{{cite web |url=http://www.newadvent.org/summa/2034.htm#article2 |title=''Summa'', II-I, Q.34., art.2 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111128084650/http://www.newadvent.org/summa/2034.htm#article2 |archive-date=28 November 2011}}</ref><ref>{{cite web |url=http://www.newadvent.org/summa/2002.htm#article6 |title=''Summa'', II-I, Q.2, art.6 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111204143359/http://www.newadvent.org/summa/2002.htm#article6 |archive-date=4 December 2011}}</ref> and the [[Stoicism|Stoic]] view that emotions are vices by nature.<ref>{{cite web |url=http://www.newadvent.org/summa/2024.htm#article2 |title=''Summa'', II-I, Q.24, art.2 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109215138/http://newadvent.org/summa/2024.htm#article2 |archive-date=9 November 2011}}</ref> Aquinas takes a moderate view of emotion, quoting Augustine: "They are evil if our love is evil; good if our love is good."<ref>{{cite web |url=http://www.newadvent.org/summa/2024.htm#article1 |title=''Summa'', II-I, Q.24, art.1 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109215138/http://newadvent.org/summa/2024.htm#article1 |archive-date=9 November 2011}}</ref> While most emotions are morally neutral, some are inherently virtuous (e.g. pity)<ref>{{cite web |url=http://www.newadvent.org/summa/2024.htm#article4 |title=''Summa'', II-I, Q.24, art.4 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109215138/http://newadvent.org/summa/2024.htm#article4 |archive-date=9 November 2011}}</ref> and some are inherently vicious (e.g. envy).<ref>{{cite web |url=http://www.newadvent.org/summa/3036.htm |title=''Summa'', II-II, Q.36 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111110162024/http://www.newadvent.org/summa/3036.htm |archive-date=10 November 2011}}</ref>

Thomist ethics hold that it is necessary to observe both [[Attendant circumstance|circumstances]]<ref>{{cite web |url=http://www.newadvent.org/summa/2018.htm |title=''Summa'', II-I, Q.18, art.3 & 10 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111110152607/http://newadvent.org/summa/2018.htm |archive-date=10 November 2011}}</ref> and [[intention]]<ref>{{cite web |url=http://www.newadvent.org/summa/2019.htm#article1 |title=''Summa'', II-I, Q.19, art.1 & 2 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111103035315/http://www.newadvent.org/summa/2019.htm#article1 |archive-date=3 November 2011}}</ref> to determine an action's [[moral value]], and therefore Aquinas cannot be said to be strictly either a [[deontological ethics|deontologicalist]] or a [[consequentialism|consequentialist]]. Rather, he would say that an action is morally good if it fulfills God's antecedent will.<ref>{{cite web |url=http://www.op-stjoseph.org/Students/study/thomas/QDdeVer23.htm#7 |title=''De veritate'', Q. 23, art.7 |publisher=Op-stjoseph.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20090503051728/http://www.op-stjoseph.org/Students/study/thomas/QDdeVer23.htm#7 |archive-date=3 May 2009}}</ref>

Of note is the [[principle of double effect]], formulated in the ''Summa'', II-II, Q.64, art.7, which is a justification of [[homicide]] in [[self-defense]]. Previously experiencing difficulties in the world of [[Christian philosophy]], the doctrine of [[Just War]] was expounded by Aquinas with this principle. He says:

{{Quote|In order for a war to be just, three things are necessary. First, the authority of the sovereign by whose command the war is to be waged... Secondly, a [[Jus ad bellum|just cause is required]], namely that those who are attacked, should be attacked because they deserve it on account of some fault... Thirdly, it is necessary that the belligerents should have a rightful intention, so that they intend the advancement of good, or the avoidance of evil...|[http://www.newadvent.org/summa/3040.htm#article1 ''Summa'', II-II, Q.40, art.1.]}}

=== Law ===
{{Main|Treatise on Law}}
Thomism recognizes four different species of law, which he defines as "an ordinance of reason for the common good, made by him who has care of the community, and promulgated":<ref>{{cite web |url=http://www.newadvent.org/summa/2090.htm#article4 |title=''Summa'', II-I, Q.90, art.4 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111102163652/http://www.newadvent.org/summa/2090.htm#article4 |archive-date=2 November 2011}}</ref>
# Eternal law, which is "the type of Divine Wisdom, as directing all actions and movements;"<ref>{{cite web |url=http://www.newadvent.org/summa/2093.htm#article1 |title=''Summa'', II-I, Q.93, art. 1 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109212726/http://newadvent.org/summa/2093.htm#article1 |archive-date=9 November 2011}}</ref>
# [[Natural law]], "whereby each one knows, and is conscious of, what is good and what is evil", which is the rational being's participation in the eternal law;<ref>[[Thomas Aquinas]] cites [http://www.newadvent.org/bible/rom002.htm Romans 2:14] {{webarchive|url=https://web.archive.org/web/20091029200412/http://www.newadvent.org/bible/rom002.htm |date=29 October 2009 }} authoritatively on the definition of [[natural law]], in [http://www.newadvent.org/summa/2091.htm#article2 ''Summa'', II-I, Q.91, art.2.] {{webarchive|url=https://web.archive.org/web/20070704182120/http://www.newadvent.org/summa/2091.htm |date=4 July 2007 }}</ref>
# Human or temporal law, laws made by humans by necessity;<ref>{{cite web |url=http://www.newadvent.org/summa/2095.htm#article1 |title=''Summa'', II-I, Q.95, art.1 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109214550/http://newadvent.org/summa/2095.htm#article1 |archive-date=9 November 2011}}</ref> and
# [[Divine law]], which are [[moral imperative]]s specifically given through [[revelation]].<ref>[http://www.newadvent.org/summa/2091.htm#article4 ''Summa'', II-I, Q.91, art.4.] {{webarchive|url=https://web.archive.org/web/20070704182120/http://www.newadvent.org/summa/2091.htm |date=4 July 2007 }} "By the natural law the eternal law is participated proportionately to the capacity of human nature. But to his supernatural end man needs to be directed in a yet higher way. Hence the additional law given by God, whereby man shares more perfectly in the eternal law."</ref>

The development of natural law is one of the most influential parts of Thomist philosophy.<ref>Cf. [https://www.vatican.va/holy_father/john_paul_ii/encyclicals/documents/hf_jp-ii_enc_06081993_veritatis-splendor_en.html ''Veritatis splendor'', 12.] {{webarchive|url=https://web.archive.org/web/20141027082206/https://www.vatican.va/holy_father/john_paul_ii/encyclicals/documents/hf_jp-ii_enc_06081993_veritatis-splendor_en.html |date=27 October 2014 }}</ref> Aquinas says that "[the law of nature] is nothing other than the light of the intellect planted in us by God, by which we know what should be done and what should be avoided. God gave this light and this law in creation... For no one is ignorant that what he would not like to be done to himself he should not do to others, and similar norms."<ref>{{cite web |url=http://www.op-stjoseph.org/Students/study/thomas/TenCommandments.htm#0 |title=St. Thomas Aquinas's commentary on the Ten Commandments, prologue, sec. 'A fourfold law' |publisher=Op-stjoseph.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20090915183817/http://www.op-stjoseph.org/Students/study/thomas/TenCommandments.htm |archive-date=15 September 2009}}</ref>

Aquinas argues that the [[Mosaic covenant]] was divine, though rightfully only given to the Jews before [[Christian views of Jesus|Christ]];<ref>{{cite web |url=http://www.newadvent.org/summa/2098.htm |title=''Summa'', II-I, Q.98, art.1 & 4–5 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109221104/http://newadvent.org/summa/2098.htm |archive-date=9 November 2011}}</ref> whereas the [[New Covenant]] [[Supersessionism|replaces the Old Covenant]]<ref>{{cite web |url=http://www.newadvent.org/summa/2107.htm#article2 |title=''Summa'', II-I, Q.107, art.2 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109213057/http://newadvent.org/summa/2107.htm#article2 |archive-date=9 November 2011}}</ref> and is meant for all humans.<ref>{{cite web |url=http://www.newadvent.org/summa/2106.htm#article4 |title=''Summa'', II-I, Q.106, art.4 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20170507202946/http://newadvent.org/summa/2106.htm#article4 |archive-date=7 May 2017}}</ref>

=== Free will ===
Aquinas argues that [[Argument from free will|there is no contradiction]] between God's [[divine providence|providence]] and human [[free will]]:

{{Quote|... just as by moving natural causes [God] does not prevent their acts being natural, so by moving voluntary causes He does not deprive their actions of being voluntary: but rather is He the cause of this very thing in them; for He operates in each thing according to its own nature.|[http://www.newadvent.org/summa/1083.htm#article1 ''Summa'', I., Q.83, art.1.]}}

Aquinas argues that God offers man both a prevenient grace to enable him to perform supernaturally good works, and cooperative grace within the same. The relation of prevenient grace to voluntariness has been the subject of further debate; the position known here as "Thomist" was originated by [[Domingo Báñez]]<ref>[[Ludwig Ott]], Grundriss der Dogmatik, nova & vetera, Bonn 2005, IV/I § 15</ref> and says that God gives an additional grace (the "efficient grace") to the [[predestination|predestined]] which makes them accept, while [[Luis de Molina]] held that God distributes grace according to a middle knowledge, and man can accept it without a different grace. [[Molinism]] is a school that is part of Thomism in the general sense (it originated in commentaries to Aquinas), yet it must be borne in mind that, here, Thomism and Molinism oppose each other. (The question has been declared undecided by the [[Holy See]].)

== Epistemology ==
{{Quote|"Whatever is in our [[intellect]] must have previously been in the [[senses]]."|[[Thomas Aquinas]], the [[peripatetic axiom]].<ref>{{cite web |url=http://www.op-stjoseph.org/Students/study/thomas/QDdeVer2.htm#3 |title=''De veritate'', Q.2, art.3, answer 19 |publisher=Op-stjoseph.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20090503051708/http://www.op-stjoseph.org/Students/study/thomas/QDdeVer2.htm#3 |archive-date=3 May 2009}}</ref>}}

Aquinas preceded the existence of the discipline of [[epistemology]], which began among modern thinkers whose positions, following in the wake of Descartes, are fundamentally opposed to Aquinas'. Nonetheless, a Thomistic theory of knowledge can be derived from a mixture of Aquinas' logical, psychological, metaphysical, and even Theological doctrines. Aquinas' thought is an instance of the [[correspondence theory of truth]], which says that something is [[truth|true]] "when it conforms to the external reality."<ref>{{cite web |url=http://www.op-stjoseph.org/Students/study/thomas/QDdeVer1.htm#3 |title=''De veritate'', Q. 1, art. 3 |publisher=Op-stjoseph.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20090424063600/http://www.op-stjoseph.org/Students/study/thomas/QDdeVer1.htm#3 |archive-date=24 April 2009}}</ref> Therefore, any being that [[existence|exists]] can be said to be true insofar that it participates in the world.<ref>{{cite web |url=http://www.newadvent.org/summa/1016.htm#article6 |title=''Summa'', I, Q.16, art.6 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20120106040340/http://www.newadvent.org/summa/1016.htm#article6 |archive-date=6 January 2012}}</ref>

Aristotle's ''[[De anima]]'' (''On the Soul'') divides the [[mind]] into three parts: [[Sense|sensation]], [[imagination]] and [[intellect]]ion. When one perceives an object, his mind composites a sense-image. When he [[memory|remembers]] the object he previously sensed, he is imagining its [[Substantial form|form]] (the image of the imagination is often translated as "phantasm"). When he extracts information from this phantasm, he is using his intellect.<ref>{{cite web |url=http://www.op-stjoseph.org/Students/study/thomas/DeAnima.htm#212 |title=''De anima'', Bk. II, Chp. V, 417b18–418a25 |publisher=Op-stjoseph.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20100107031219/http://www.op-stjoseph.org/Students/study/thomas/DeAnima.htm#212 |archive-date=7 January 2010}}</ref> Consequently, all human knowledge concerning [[Universal (metaphysics)|universals]] (such as [[species]] and [[Property (philosophy)|properties]]) are derived from the phantasm ("the received is in the receiver according to the mode of the receiver"<ref>{{cite web |url=http://www.newadvent.org/summa/1084.htm#article1 |title=''Summa'', I, Q.84, art.1 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111102165338/http://www.newadvent.org/summa/1084.htm#article1 |archive-date=2 November 2011}}</ref>), which itself is a recollection of an experience. Concerning the question of "Whether the intellect can actually understand through the intelligible species of which it is possessed, without turning to the phantasms?" in the ''[[Summa Theologica]]'', Aquinas quotes Aristotle in the ''sed contra'': "the soul understands nothing without a phantasm."<ref>{{cite web |url=http://www.newadvent.org/summa/1084.htm#article7 |title=''Summa'', I, Q.84, art.7 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111102165338/http://www.newadvent.org/summa/1084.htm#article7 |archive-date=2 November 2011}}</ref> Hence the peripatetic axiom. (Another theorem to be drawn from this is that [[error]] is a result of drawing false conclusions based on our sensations.)<ref>{{cite web |url=http://www.op-stjoseph.org/Students/study/thomas/DeAnima.htm#37 |title=St. Thomas Aquinas's commentary on ''De anima'', §688 |publisher=Op-stjoseph.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20100107031219/http://www.op-stjoseph.org/Students/study/thomas/DeAnima.htm#37 |archive-date=7 January 2010}}</ref>

Aquinas' [[Epistemology|epistemological theory]] would later be classified as [[empiricism]], for holding that sensations are a necessary step in acquiring knowledge, and that [[deductive logic|deductions]] cannot be made from [[rationalism|pure reason]].<ref>{{cite web |url=http://www.newadvent.org/summa/1084.htm#article8 |title=''Summa'', I, Q.84, art.8 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111102165338/http://www.newadvent.org/summa/1084.htm#article8 |archive-date=2 November 2011}}</ref>

== Impact==
Aquinas shifted [[Scholasticism]] away from [[neoplatonism]] and towards [[Aristotle]]. The ensuing school of thought, through its influence on Catholicism and the ethics of the Catholic school, is one of the most influential philosophies of all time, also significant due to the number of people living by its teachings.<ref>{{Cite book|page=95|title=On the History of Political Philosophy: Great Political Thinkers from Thucydides to Locke|author=W Julian Korab-Karpowicz|isbn=9781317346012|publisher=Routledge|year=2015}}</ref>
[[File:Benozzo Gozzoli - Triumph of St Thomas Aquinas - WGA10334.jpg|thumb|left|200px| Triumph of St Thomas Aquinas, [[Benozzo Gozzoli]],1471. Louvre, Paris]]

Before Aquinas' death, [[Stephen Tempier]], [[Bishop of Paris]], forbade certain positions associated with Aquinas (especially his denial of both universal ''[[hylomorphism]]'' and a plurality of [[substantial form]]s in a single substance) to be taught in the [[University of Paris|Faculty of Arts at Paris]]. Through the influence of traditional Augustinian theologians, some theses of Aquinas were [[Condemnations of 1210–1277|condemned in 1277]] by the ecclesiastical authorities of Paris and [[University of Oxford|Oxford]] (the most important theological schools in the [[Middle Ages]]). The [[Franciscan Order]] opposed the ideas of the [[Order of Preachers|Dominican]] Aquinas, while the Dominicans institutionally took up the defense of his work (1286), and thereafter adopted it as an official philosophy of the order to be taught in their ''studia''. Early opponents of Aquinas include [[William de la Mare]], [[Henry of Ghent]], [[Giles of Rome]], and [[Duns Scotus|Jon Duns Scotus]].<ref>{{Cite book|page=[https://archive.org/details/shorthistorythom00cess/page/n55 41]|title=A Short History of Thomism|url=https://archive.org/details/shorthistorythom00cess|url-access=limited|isbn= 9780813213866|first1=Romanus|last1= Cessario|first2=Romanus|last2=O. P.|year=2005|publisher=CUA Press}}</ref><ref>{{Cite web|url=https://www.britannica.com/biography/William-de-la-Mare|title=William De La Mare &#124; English Philosopher, Medieval Scholar & Theologian &#124; Britannica|website=www.britannica.com}}</ref>

Early and noteworthy defenders of Aquinas were his former teacher [[Albertus Magnus]], the ill-fated Richard Knapwell, [[William Macclesfeld]], [[Giles of Lessines]], [[John of Quidort]], [[Bernard of Auvergne]] and [[Thomas of Sutton]].<ref>{{Cite book|title=The Church Triumphant: A History of Christianity Up to 1300|first1=E. Glenn|last1=Hinson|page=52|publisher=Mercer University Press|isbn=9780865544369|year=1995}}</ref><ref>{{Cite web|url=https://www.oxfordbibliographies.com/display/document/obo-9780195396584/obo-9780195396584-0146.xml|title=Richard Knapwell|website=obo}}</ref><ref>{{Cite book|page=48|title=Boethius in the Middle Ages: Latin and Vernacular Traditions of the Consolatio Philosophiae|publisher=BRILL|isbn=9789004108318|year=1997}}</ref><ref>{{Cite web|url=http://www.domcentral.org/trad/domwork/domwork09.htm|title=Work 9: The Doctrinal Life and the Thomistic School|website=www.domcentral.org}}</ref><ref>Roensch, Frederick J. Early Thomistic School. Dubuque, IA: Priory Press, 1964.</ref><ref>{{Cite web|url=https://www.oxfordreference.com/display/10.1093/oi/authority.20110803095501926|title=Bernard of Auvergne|website=Oxford Reference}}</ref><ref>{{Cite web|url=http://www.fordham.edu/gsas/phil/klima/TS.htm|title=Gyula Klima, ''Thomas of Sutton on the Nature of the Intellective Soul and the Thomistic Theory of Being''}}</ref>
The [[canonization]] of Aquinas in 1323 led to a revocation of the condemnation of 1277. Later, Aquinas and his school would find a formidable opponent in the ''via moderna'', particularly in [[William of Ockham]] and his adherents.

Thomism remained a doctrine held principally by Dominican theologians, such as [[Giovanni Capreolo]] (1380–1444) or [[Thomas Cajetan|Tommaso de Vio]] (1468–1534). Eventually, in the 16th century, Thomism found a stronghold on the Iberian Peninsula, through for example the Dominicans [[Francisco de Vitoria]] (particularly noteworthy for his work in natural law theory), [[Domingo de Soto]] (notable for his work on economic theory), [[John of St. Thomas]], and [[Domingo Báñez]]; the Carmelites of Salamanca (i.e., the [[School of Salamanca|Salmanticenses]]); and even, in a way, the newly formed [[Jesuits]], particularly [[Francisco Suárez]], and [[Luis de Molina]].

The modern period brought considerable difficulty for Thomism.<ref name="decline">{{CathEncy|last=Kennedy|first=Daniel|wstitle=Thomism|volume=14}} "Gradually, however, during the seventeenth and eighteenth centuries, there came a decline in the study of the works of the great Scholastics."</ref>

Pope [[Leo XIII]] attempted a Thomistic revival, particularly with his 1879 encyclical ''[[Aeterni Patris]]'' and his establishment of the Leonine Commission, established to produce critical editions of Aquinas' ''opera omnia''. This encyclical served as the impetus for the rise of Neothomism, which brought an emphasis on the [[ethic]]al parts of Thomism, as well as a large part of its views on life, humans, and theology, are found in the various schools of [[Neothomism]]. Neothomism held sway as the dominant philosophy of the Roman Catholic Church until the [[Second Vatican Council]], which seemed, in the eyes of ''[[Homiletic and Pastoral Review]]'' writer Fr. Brian Van Hove, SJ, to confirm the significance of [[Ressourcement]] theology.<ref>{{Cite web |date=2013-12-24 |title=Looking Back at "Humani Generis" |url=https://www.hprweb.com/2013/12/looking-back-at-humani-generis/ |access-date=2023-01-16 |website=[[Homiletic & Pastoral Review]] |language=en-US}}</ref>

Thomism remains a school of philosophy today, and influential in Catholicism, though "The Church has no philosophy of her own nor does she canonize any one particular philosophy in preference to others."<ref>{{cite web |author=John Paul II |url=https://www.vatican.va/holy_father/john_paul_ii/encyclicals/documents/hf_jp-ii_enc_15101998_fides-et-ratio_en.html |title=''Fides et ratio'', 49 |publisher=Vatican.va |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111126183043/https://www.vatican.va/holy_father/john_paul_ii/encyclicals/documents/hf_jp-ii_enc_15101998_fides-et-ratio_en.html |archive-date=26 November 2011}}</ref>

In recent years, the cognitive neuroscientist [[Walter J. Freeman (neuroscientist)|Walter Freeman]] proposes that Thomism is the philosophical system explaining cognition that is most compatible with [[neurodynamics]], in a 2008 article in the journal ''Mind and Matter'' entitled "Nonlinear Brain Dynamics and Intention According to Aquinas."

==Connection with Jewish thought==
Aquinas did not disdain to draw upon [[Jewish philosophy|Jewish philosophical]] sources. His main work, the ''[[Summa Theologica]]'', shows a profound knowledge not only of the writings of [[Avicebron]] (Ibn Gabirol), whose name he mentions, but also of most Jewish philosophical works then existing.

Aquinas pronounces himself energetically<ref>{{cite web |url=http://www.newadvent.org/summa/1003.htm#article7 |title=''Summa'', I, Q.3, art. 7 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109160402/http://newadvent.org/summa/1003.htm#article7 |archive-date=9 November 2011}}</ref> against the hypothesis of the eternity of the world, in agreement with both [[Christian theology|Christian]] and [[Jewish theology]]. But as this theory is attributed to [[Aristotle]], he seeks to demonstrate that the latter did not express himself categorically on this subject. "The argument", said he, "which Aristotle presents to support this thesis is not properly called a demonstration, but is only a reply to the theories of those ancients who supposed that this world had a beginning and who gave only impossible proofs. There are three reasons for believing that Aristotle himself attached only a relative value to this reasoning..."<ref>{{cite web |url=http://www.newadvent.org/summa/104601.htm#article1 |title=''Summa'', I, Q.46., art.1 |publisher=Newadvent.org |access-date=20 November 2011 |url-status=dead |archive-url=https://web.archive.org/web/20070222131511/http://www.newadvent.org/summa/104601.htm#article1 |archive-date=22 February 2007}}</ref> In this, Aquinas paraphrases [[Maimonides]]' ''[[Guide for the Perplexed]]'', where those reasons are given.<ref>[[Maimonides]], ''[[s:The Guide for the Perplexed (Friedlander)|The Guide for the Perplexed]]'', (I:2,15).</ref>

==Scholarly perspectives==

{{anchor|Individual thinkers}}

===René Descartes===
Thomism began to decline in popularity in the [[Modern philosophy|modern period]],<ref name="decline" /> which was inaugurated by [[René Descartes]]' works ''[[Discourse on the Method]]'' in 1637 and ''[[Meditations on First Philosophy]]'' in 1641. The [[Cartesianism|Cartesian]] doctrines of [[mind–body dualism]] and the fallibility of the senses{{vague|date=December 2022}} implicitly contradicted [[Aristotle]] and [[Thomas Aquinas|Aquinas]]:

{{Quote|But, meanwhile, I feel greatly astonished when I observe [the weakness of my mind, and] its proneness to error. For although, without at all giving expression to what I think, I consider all this in my own mind, words yet occasionally impede my progress, and I am almost led into error by the terms of ordinary language. We say, for example, that we see the same wax when it is before us, and not that we judge it to be the same from its retaining the same color and figure: whence I should forthwith be disposed to conclude that the wax is known by the act of sight, and not by the intuition of the mind alone, were it not for the analogous instance of human beings passing on in the street below, as observed from a window. In this case I do not fail to say that I see the men themselves, just as I say that I see the wax; and yet what do I see from the window beyond hats and cloaks that might cover artificial machines, whose motions might be determined by springs? But I judge that there are human beings from these appearances, and thus I comprehend, by the faculty of judgment alone which is in the mind, what I believed I saw with my eyes.|[[s:Meditations on First Philosophy/Meditation II|''Meditations on First Philosophy'', Med. II, §13.]]}}

===G. K. Chesterton===
In describing Thomism as a philosophy of common sense, [[G. K. Chesterton]] wrote:
{{Quote|
Since the modern world began in the sixteenth century, nobody's system of philosophy has really corresponded to everybody's sense of reality; to what, if left to themselves, common men would call common sense. Each started with a paradox; a peculiar point of view demanding the sacrifice of what they would call a sane point of view. That is the one thing common to [[Hobbes]] and [[Hegel]], to [[Immanuel Kant|Kant]] and [[Bergson]], to [[George Berkeley|Berkeley]] and [[William James]]. A man had to believe something that no normal man would believe, if it were suddenly propounded to his simplicity; as that law is above right, or right is outside reason, or things are only as we think them, or everything is relative to a reality that is not there. The modern philosopher claims, like a sort of confidence man, that if we will grant him this, the rest will be easy; he will straighten out the world, if he is allowed to give this one twist to the mind...

Against all this the philosophy of St. Thomas stands founded on the universal common conviction that eggs are eggs. The Hegelian may say that an egg is really a hen, because it is a part of an endless process of Becoming; the Berkelian may hold that [[poached egg]]s only exist as a dream exists, since it is quite as easy to call the dream the cause of the eggs as the eggs the cause of the dream; the Pragmatist may believe that we get the best out of scrambled eggs by forgetting that they ever were eggs, and only remembering the scramble. But no pupil of St. Thomas needs to addle his brains in order adequately to addle his eggs; to put his head at any peculiar angle in looking at eggs, or squinting at eggs, or winking the other eye in order to see a new simplification of eggs. The Thomist stands in the broad daylight of the brotherhood of men, in their common consciousness that eggs are not hens or dreams or mere practical assumptions; but things attested by the Authority of the Senses, which is from God.|Chesterton, ''[[Saint Thomas Aquinas (Chesterton)|Saint Thomas Aquinas]]'', p. 147.}}

==History==
J. A. Weisheipl emphasizes that within the [[Dominican Order]] the history of Thomism has been continuous since the time of Aquinas:
{{Quote|Thomism was always alive in the Dominican Order, small as it was after the ravages of the Reformation, the French Revolution, and the Napoleonic occupation. Repeated legislation of the General Chapters, beginning after the death of St. Thomas, as well as the Constitutions of the Order, required all Dominicans to teach the doctrine of St. Thomas both in philosophy and in theology.<ref>{{cite web |url=http://domcentral.org/blog/the-revival-of-thomism-an-historical-survey-weisheipl/ |title=The Dominican Friars of the Province of St. Albert the Great » "The Revival of Thomism: An Historical Survey" (James Weisheipl) |access-date=2013-08-21 |url-status=dead |archive-url=https://web.archive.org/web/20130927202339/http://domcentral.org/blog/the-revival-of-thomism-an-historical-survey-weisheipl/ |archive-date=27 September 2013}} "The Revival of Thomism: An Historical Survey, ” James Weisheipl, 1962.</ref>}}

An idea of the longstanding historic continuity of Dominican Thomism may be derived from the [[list of people associated with the Pontifical University of St. Thomas Aquinas]].

Outside the [[Dominican Order]], Thomism has had varying fortunes leading some to periodize it historically or thematically. Weisheipl distinguishes "wide" Thomism, which includes those who claim to follow the spirit and basic insights of Aquinas and manifest an evident dependence on his texts, from "eclectic" Thomism which includes those with a willingness to allow the influence of other philosophical and theological systems in order to relativize the principles and conclusions of traditional Thomism. [[John Joseph Haldane|John Haldane]] gives an historic division of Thomism including 1) the period of Aquinas and his first followers from the 13th to 15th centuries, a second Thomism from the 16th to 18th centuries, and a Neo-Thomism from the 19th to 20th centuries.<ref>John Haldane, 1998. "Thomism". In E. Craig (Ed.), Routledge Encyclopedia of Philosophy. London: Routledge. Retrieved 18 August 2013, from http://www.rep.routledge.com/article/N067</ref>

One might justifiably articulate other historical divisions on the basis of shifts in perspective on Aquinas' work including the period immediately following Aquinas' canonization in 1325, the period following the [[Council of Trent]], and the period after the Second Vatican Council. Romanus Cessario thinks it better not to identify intervals of time or periods within the larger history of Thomism because Thomists have addressed such a broad variety of issues and in too many geographical areas to permit such divisions.<ref>''A Short History of Thomism'', Catholic University of America Press, 2005</ref>

===First Thomistic School===
The first period of Thomism stretches from Aquinas' teaching activity beginning in 1256 at Paris to Cologne, Orvieto, Viterbo, Rome, and Naples until his canonization in 1325. In this period his doctrines "were both attacked and defended" as for example after his death (1274) the condemnations of 1277, 1284 and 1286 were counteracted by the General Chapters of the [[Dominican Order]] and other disciples who came to Aquinas' defense.<ref name="Roensch1964">{{cite book|author=Frederick J. Roensch|title=Early Thomistic school|url=https://books.google.com/books?id=v0lDAAAAIAAJ|date=1 January 1964|publisher=Priory Press|isbn=9780840120410 }}</ref>

===1325 to the Council of Trent===
After Aquinas' canonisation, commentaries on Aquinas increased, especially at Cologne which had previously been a stronghold of [[Albertus Magnus|Albert the Great's]] thought. Henry of Gorkum (1386-1431) wrote what may well be the earliest commentary on the Summa Theologiae, followed in due course by his student [[Denis the Carthusian]].<ref>{{cite web |last1=Upham |first1=Christopher |title=The Influence of Aquinas |url=https://www.oxfordhandbooks.com/view/10.1093/oxfordhb/9780195326093.001.0001/oxfordhb-9780195326093-e-39 |website=Oxford Handbooks |year=2012 |pages=511–532 |publisher=Oxford 2012 |doi=10.1093/oxfordhb/9780195326093.013.0039 |isbn=978-0195326093 |access-date=7 May 2019}}</ref>

===Council of Trent to ''Aeterni Patris''===
Responding to prevailing philosophical rationalism during the Enlightenment Salvatore Roselli, professor of theology at the College of St. Thomas, the future [[Pontifical University of Saint Thomas Aquinas|Pontifical University of Saint Thomas Aquinas, ''Angelicum'']] in Rome,<ref name="Leon2013">{{cite book|author=Sharon M. Leon|title=An Image of God: The Catholic Struggle with Eugenics|url=https://books.google.com/books?id=6BDmuuAe3gcC&pg=PA21|date=5 June 2013|publisher=University of Chicago Press|isbn=978-0-226-03898-8|pages=21–}}</ref> published a six volume ''Summa philosophica'' (1777) giving an Aristotelian interpretation of Aquinas validating the senses as a source of knowledge.<ref>http://www.saintwiki.com/index.php?title=Hinnebusch/The_Dominicans:_A_Short_History/Chapter_IX {{webarchive|url=https://web.archive.org/web/20140517120036/http://www.saintwiki.com/index.php?title=Hinnebusch%2FThe_Dominicans%3A_A_Short_History%2FChapter_IX |date=17 May 2014 }} Accessed 30 August 2013</ref> While teaching at the College Roselli is considered to have laid the foundation for Neothomism in the nineteenth century.<ref>{{cite web |url=http://www.encyclopedia.com/article-1G2-3407709691/roselli-salvatore-maria.html |title=Roselli, Salvatore Maria - New Catholic Encyclopedia &#124; Encyclopedia.com |access-date=2014-06-29 |url-status=live |archive-url=https://web.archive.org/web/20150117181442/http://www.encyclopedia.com/article-1G2-3407709691/roselli-salvatore-maria.html |archive-date=17 January 2015}}, ''Roselli, Salvatore Maria'', New Catholic Encyclopedia, 2003, Roensch, F. J.: "...he furnished the basis for the Thomistic reconstruction of the 19th century; {{cite web |url=http://scholasticon.ish-lyon.cnrs.fr/Database/Scholastiques_fr.php?ID=1101 |title=Roselli, Salvatore Maria - Scholasticon |access-date=2015-08-07 |url-status=live |archive-url=https://web.archive.org/web/20151208161010/http://scholasticon.ish-lyon.cnrs.fr/Database/Scholastiques_fr.php?ID=1101 |archive-date=8 December 2015}} Accessed 7 August 2015; ''Scholasticon'' calls Roselli "l'un des principaux ancêtres du néo-thomisme du XIXe siècle. Accessed 28 June 2014</ref> According to historian J.A. Weisheipl in the late 18th and early 19th centuries "everyone who had anything to do with the revival of Thomism in Italy, Spain and France was directly influenced by Roselli’s monumental work.<ref>"The Revival of Thomism: An Historical Survey", James Weisheipl, 1962 {{cite web |url=http://domcentral.org/blog/the-revival-of-thomism-an-historical-survey-weisheipl/ |title=The Dominican Friars of the Province of St. Albert the Great » "The Revival of Thomism: An Historical Survey" (James Weisheipl) |access-date=2013-08-21 |url-status=dead |archive-url=https://web.archive.org/web/20130927202339/http://domcentral.org/blog/the-revival-of-thomism-an-historical-survey-weisheipl/ |archive-date=27 September 2013}} Accessed 30 August 2013</ref>

===''Aeterni Patris'' to Vatican II===
{{Main|Neo-Scholasticism}}
The Thomist revival that began in the mid-19th century, sometimes called "neo-scholasticism" or "neo-Thomism", can be traced to figures such as ''[[Pontifical University of Saint Thomas Aquinas|Angelicum]]'' professor [[Tommaso Maria Zigliara]], [[Society of Jesus|Jesuits]] [[Josef Kleutgen]], and [[Giovanni Maria Cornoldi]], and [[Secular clergy|secular priest]] [[Gaetano Sanseverino]]. This movement received impetus from [[Pope Leo XIII]]'s [[encyclical]] ''[[Aeterni Patris]]'' of 1879. Generally the revival accepts the interpretative tradition of Aquinas' great commentators such as [[Jean Capréolus|Capréolus]], [[Thomas Cajetan|Cajetan]], and [[John of St. Thomas]]. Its focus, however, is less exegetical and more concerned with carrying out the program of deploying a rigorously worked out system of Thomistic metaphysics in a wholesale critique of modern philosophy. Other seminal figures in the early part of the century include [[Martin Grabmann]] (1875-1949) and Amato Masnovo (1880-1955). The movement's core philosophical commitments are summarized in "Twenty-Four Thomistic Theses" approved by [[Pope Pius X]].<ref name="Feser">{{cite web|title=The Thomistic tradition (Part 1)|url=http://edwardfeser.blogspot.com/2009/10/thomistic-tradition-part-i.html|author=Feser, Edward|date=15 October 2009|access-date=2011-01-02|url-status=live|archive-url=https://web.archive.org/web/20101129133527/http://edwardfeser.blogspot.com/2009/10/thomistic-tradition-part-i.html|archive-date=29 November 2010}}</ref>

In the first half of the twentieth century ''[[Pontifical University of Saint Thomas Aquinas|Angelicum]]'' professors [[Edouard Hugon]], [[Réginald Garrigou-Lagrange]] among others, carried on Leo's call for a Thomist revival. Their approach is reflected in many of the manuals<ref>e.g., Thomas Aquinas (1952), edd., Walter Farrell, [[Order of Preachers|OP]], [[Master of Sacred Theology|STM]], and Martin J. Healy, [[Doctor of Sacred Theology|STD]], ''My Way of Life:  Pocket Edition of St. Thomas—The Summa Simplified for Everyone'', Brooklyn, NY:  Confraternity of the Precious Blood.</ref> and textbooks widely in use in Roman Catholic colleges and seminaries before [[Vatican II]].

While the [[Second Vatican Council]] took place from 1962 to 1965 [[Cornelio Fabro]] was already able to write in 1949 that the century of revival with its urgency to provide a synthetic systematization and defense of Aquinas' thought was coming to an end. Fabro looked forward to a more constructive period in which the original context of Aquinas' thought would be explored.<ref>''La nozione Metafisica di Participazione'', Cornelio Fabro, Preface to the second edition, 5; https://www.scribd.com/doc/90016006/Fabro-La-Nozione-Metafisica-Di-Partecipazione{{dead link|date=May 2018 |bot=SheriffIsInTown |fix-attempted=yes }} Accessed 30 August 2013</ref> [[Carol Jackson Robinson]] wrote popular articles and books in the service of Thomism after Vatican II. 

==Recent schools and interpretations==
A summary of some recent and current schools and interpretations of Thomism can be found, among other places, in ''La Metafisica di san Tommaso d'Aquino e i suoi interpreti'' (2002), by Battista Mondin, ''Being and Some 20th Century Thomists'' (2003), by [[John F. X. Knasas]] as well as in the writing of [[Edward Feser]].<ref name=:0>{{cite web |url=http://edwardfeser.blogspot.com/2009/10/thomistic-tradition-part-i.html |author=Edward Feser |title=The Thomistic tradition, Part I |date=15 October 2009 |access-date=2011-01-02 |url-status=live |archive-url=https://web.archive.org/web/20101129133527/http://edwardfeser.blogspot.com/2009/10/thomistic-tradition-part-i.html |archive-date=29 November 2010|author-link=Edward Feser }} Accessed 27 March 2013</ref>

===Neo-Scholastic Thomism===
{{Main|Neo-scholasticism}}
[[Neo-Scholastic Thomism]]<ref name=:0/> identifies with the philosophical and theological tradition stretching back to the time of St. Thomas. In the nineteenth century authors such as [[Tommaso Maria Zigliara]] focused not only on exegesis of the historical Aquinas but also on the articulation of a rigorous system of orthodox Thomism to be used as an instrument of critique of contemporary thought.

Due to its suspicion of attempts to harmonize Aquinas with non-Thomistic categories and assumptions, Neo-Scholastic Thomism has sometimes been called "[[strict observance Thomism]]."<ref name=:0/> A discussion of recent and current Neo-Scholastic Thomism can be found in ''La Metafisica di san Tommaso d'Aquino e i suoi interpreti'' (2002) by Battista Mondin, which includes such figures as [[Martin Grabmann]], [[Reginald Garrigou-Lagrange]], Sofia Vanni Rovighi (1908–1990),<ref>{{cite web |url=http://www.treccani.it/enciclopedia/sofia-vanni-rovighi_(Dizionario-di-filosofia)/ |title=Vanni Rovighi, Sofia in "Dizionario di filosofia" |access-date=2013-09-25 |url-status=live |archive-url=https://web.archive.org/web/20131004001024/http://www.treccani.it/enciclopedia/sofia-vanni-rovighi_(Dizionario-di-filosofia)/ |archive-date=4 October 2013}} Accessed 17 August 2013</ref> [[Cornelio Fabro]] (1911–1995), Carlo Giacon (1900–1984),<ref>{{cite web |url=http://www.treccani.it/enciclopedia/carlo-giacon_(Dizionario-Biografico)/ |title=GIACON, Carlo in "Dizionario Biografico" |access-date=2013-09-25 |url-status=live |archive-url=https://web.archive.org/web/20131004001026/http://www.treccani.it/enciclopedia/carlo-giacon_(Dizionario-Biografico)/ |archive-date=4 October 2013}} Accessed 9 April 2013</ref> [[Tomáš Týn]] (1950–1990), Abelardo Lobato (1925–2012), Leo Elders (1926–2019) and [[Ventimiglia Giovanni|Giovanni Ventimiglia]] (b. 1964) among others. Fabro in particular emphasizes Aquinas' originality, especially with respect to the ''actus essendi'' or act of existence of finite beings by participating in being itself. Other scholars such as those involved with the "Progetto Tommaso"<ref>{{cite web |url=http://www.istitutotomistico.it/risorse/testi_arca.htm |title=Istituto Filosofico di Studi Tomistici |access-date=2013-09-25 |url-status=live |archive-url=https://web.archive.org/web/20130927140929/http://www.istitutotomistico.it/risorse/testi_arca.htm |archive-date=27 September 2013}} Accessed 5 Sept. 2013</ref> seek to establish an objective and universal reading of Aquinas' texts.<ref>See Raffaele Rizzello’s "Il Progetto Tommaso", in ''Vita quaerens intellectum'', eds. Giacomo Grasso and Stefano Serafini, Millennium Romae, Rome 1999, pp. 157–161. {{cite web |url=http://www.phmae.it/rec35.htm |title=S. Serafini - G. Grasso - Vita quaerens intellectum |access-date=2013-09-25 |url-status=dead |archive-url=https://web.archive.org/web/20130928013141/http://www.phmae.it/rec35.htm |archive-date=28 September 2013}} Accessed 5 Sept. 2013</ref>

===Cracow Circle Thomism<!--'Cracow Circle Thomism' redirects here-->===
'''Cracow Circle Thomism'''<ref name=:0/> (named after [[Kraków]]) has been called "the most significant expression of Catholic thought between the two World Wars."<ref name="segr-did2.fmag.unict.it">{{cite web |url=http://segr-did2.fmag.unict.it/~polphil/polphil/Cracow/Cracow.html |title=The Cracow Circle |access-date=2013-03-16 |url-status=live |archive-url=https://web.archive.org/web/20130313094322/http://segr-did2.fmag.unict.it/~polphil/polphil/Cracow/Cracow.html |archive-date=13 March 2013}} Accessed 15 March 2013</ref> The Circle was founded by a group of philosophers and theologians that in distinction to more traditional Neo-Scholastic Thomism embraced modern formal logic as an analytical tool for traditional Thomist philosophy and theology.<ref name="segr-did2.fmag.unict.it"/>

Inspired by the logical clarity of Aquinas, members of the Circle held both philosophy and theology to contain "propositions with truth-values…a structured body of propositions connected in meaning and subject matter, and linked by logical relations of compatibility and incompatibility, entailment etc." "The Cracow Circle set about investigating and where possible improving this logical structure with the most advanced logical tools available at the time, namely those of modern mathematical logic, then called 'logistic'."<ref>"Bocheński and Balance: System and History in Analytic Philosophy", Peter Simons, ''Studies in East European Thought'' 55 (2003), 281–297, Reprinted in: Edgar Morscher, Otto Neumaier and Peter Simons, ''Ein Philosoph mit "Bodenhaftung": Zu Leben und Werk von Joseph M. Bocheński''. St.Augustin: Academia, 2011, 61–79</ref><!--'Existential Thomism' redirects here-->

===Existential Thomism===
[[Étienne Gilson]] (1884–1978), the key proponent of '''existential Thomism''',<ref name=:0/> tended to emphasize the importance of historical exegesis but also to deemphasize Aquinas's continuity with the Aristotelian tradition, and like [[Cornelio Fabro]] of the Neo-scholastic school, to highlight the originality of Aquinas's doctrine of being as existence. He was also critical of the Neo-Scholastics' focus on the tradition of the commentators, and given what he regarded as their insufficient emphasis on being or existence accused them of "[[essentialism]]" (to allude to the other half of Aquinas's distinction between being and essence). Gilson's reading of Aquinas as putting forward a distinctively "Christian philosophy" tended, at least in the view of his critics, to blur Aquinas's distinction between philosophy and theology.<ref>Gilson wrote about the topic of [[Faith and rationality|faith and reason]] in a [http://www.u.arizona.edu/~aversa/scholastic/gilson/ chapter of his book ''Le Thomisme''] {{webarchive|url=https://web.archive.org/web/20110605082527/http://www.u.arizona.edu/~aversa/scholastic/gilson/ |date=5 June 2011 }}.</ref> [[Jacques Maritain]] (1882–1973) introduced into Thomistic metaphysics the notion that philosophical reflection begins with an "intuition of being", and in ethics and social philosophy sought to harmonize Thomism with [[personalism]] and pluralistic democracy. Though "existential Thomism" was sometimes presented as a counterpoint to modern [[existentialism]], the main reason for the label is the emphasis this approach puts on Aquinas's doctrine of existence. Other proponents include [[Joseph Owens (Redemptorist)|Joseph Owens]], [[E.R. Fairweather|Eugene Fairweather]],<ref>{{Cite journal
| last1        = Fairweather 
| first1       = E.R.
| authorlink1  = E.R. Fairweather
| year         = 1952
| title        = The Mystery of New Being
| journal      = [[Anglican Theological Review]]
| volume       = 34
| language     = English}}</ref><ref>{{cite journal | last=Crouse| first=Robert D. |author-link=R.D. Crouse| title=In Memoriam Eugene Rathbone Fairweather| journal=[[Anglican Theological Review]] | year=2003 | volume=85 | issue=1 | url=https://www.proquest.com/docview/215266116|issn=0003-3286|access-date=May 6, 2024| id={{ProQuest|215266116}} }}</ref><ref>{{cite web |url=http://anglicanhistory.org/canada/erfairweather/reynolds2004.html |title=A Celebration of Eugene Rathbone Fairweather |last=Reynolds |first=Stephen |website=[[Project Canterbury]] |series= |publisher= |agency= |location= |page= |pages= |at= |language= |script-title= |trans-title= |type= |format= |arxiv= |asin= |bibcode= |doi= |isbn= |issn= |jfm= |jstor= |lccn= |mr= |oclc= |ol= |osti= |pmc= |pmid= |rfc= |ssrn= |zbl= |id= |access-date=May 6, 2024 |via= |quote= |trans-quote= }}</ref> and [[John F. X. Knasas]].<ref name=:0/>

===River Forest Thomism<!--'River Forest Thomism', 'Laval Thomism', and 'Aristotelian Thomism' redirects here-->===
According to '''River Forest Thomism'''<ref name=:0/> (named after [[River Forest, Illinois]]), the [[natural science]]s are [[Epistemology|epistemologically]] prior to [[metaphysics]], preferably called [[<!--Science and technology studies|-->metascience]].{{additional citations needed|date=December 2022}}<ref>"[http://www.u.arizona.edu/~aversa/scholastic/riverforest/ The natural sciences are epistemologically first.] {{webarchive|url=https://web.archive.org/web/20110605084141/http://www.u.arizona.edu/~aversa/scholastic/riverforest/ |date=5 June 2011 }}" contains an excerpt from {{cite book|author=Benedict Ashley|title=The Way toward Wisdom: An Interdisciplinary and Contextual Introduction to Metaphysics|url=http://undpress.nd.edu/book/P01080|oclc=609421317|publisher=University of Notre Dame Press for the Center of Thomistic Studies|location=Houston|year=2006|url-status=live|archive-url=https://web.archive.org/web/20090404122319/http://undpress.nd.edu/book/P01080|archive-date=4 April 2009|author-link=Benedict Ashley}} comparing this chief thesis of River Forest Thomism to the objections from Lawrence Dewan, O.P.</ref> This approach emphasizes the Aristotelian foundations of Aquinas's philosophy, and in particular the idea that the construction of a sound metaphysics must be preceded by a sound understanding of natural science, as interpreted in light of an Aristotelian philosophy of nature. Accordingly, it is keen to show that modern physical science can and should be given such an interpretation. [[Charles De Koninck]], Raymond Jude Nogar, James A. Weisheipl,<ref>"Weisheipl, James Patrick Athanasius", in ''The Dictionary of Modern American Philosophers''(2005), New York: Oxford.</ref> William A. Wallace,<ref>{{ Cite web | last = Feser | first = Edward | author-link = Edward Feser | date = 2 March 2015 | title = William Wallace, OP (1918-2015) | url = https://edwardfeser.blogspot.com/2015/03/william-wallace-op-1918-2015.html | access-date = 25 November 2020 }}</ref> and [[Benedict Ashley]], are among its representatives. It is sometimes called "'''Laval Thomism'''"<ref name=:0/> after [[Laval University]] in Quebec City, where De Koninck was a professor. The alternative label "River Forest Thomism" derives from a suburb of Chicago, the location of the Albertus Magnus Lyceum for Natural Science,<ref>There is a River Forest Dominican Collection at the [[Jacques Maritain]] Center, at the University of Notre Dame. http://maritain.nd.edu . Accessed 2020 April 29.</ref> whose members have been associated with this approach. It is also sometimes called "'''Aristotelian Thomism'''"<ref name=:0/> (to highlight its contrast with Gilson's brand of existential Thomism) though since Neo-Scholastic Thomism also emphasizes Aquinas's continuity with Aristotle, this label seems a bit too proprietary. (There are writers, like the contemporary Thomist [[Ralph McInerny]] who have exhibited both Neo-Scholastic and Laval/River Forest influences, and the approaches are not necessarily incompatible.)<ref name=:0/><ref>For an excellent introduction to River Forest Thomism, see:
* {{cite book|author=Benedict Ashley|title=The Way toward Wisdom: An Interdisciplinary and Contextual Introduction to Metaphysics|url=http://undpress.nd.edu/book/P01080|oclc=609421317|publisher=University of Notre Dame Press for the Center of Thomistic Studies|location=Houston|year=2006|url-status=live|archive-url=https://web.archive.org/web/20090404122319/http://undpress.nd.edu/book/P01080|archive-date=4 April 2009|author-link=Benedict Ashley}}
* {{cite book|author=Benedict Ashley|title=Philosophy and the God of Abraham: essays in memory of James A. Weisheipl, OP|author2=Raymond James Long|chapter-url=https://books.google.com/books?id=E1inXI59EQkC&pg=PA1|chapter=The River Forest School and the Philosophy of Nature Today|year=1991|isbn=9780888448125|author-link=Benedict Ashley}}</ref>

===Transcendental Thomism<!--'Transcendental Thomism' redirects here-->===
Unlike the first three schools mentioned above, '''transcendental Thomism''',<ref name=:0/> associated with [[Joseph Maréchal]] (1878–1944), [[Karl Rahner]] (1904–84), and [[Bernard Lonergan]] (1904–84), does not oppose modern philosophy wholesale, but seeks to reconcile Thomism with a [[Cartesianism|Cartesian]] subject-centered approach to knowledge in general, and [[Kantian]] [[transcendental philosophy]]{{vague|date=December 2022}} in particular. To Feser, "It seems fair to say that most Thomists otherwise tolerant of diverse approaches to Aquinas's thought tend to regard transcendental Thomism as having conceded too much to modern philosophy genuinely to count as a variety of Thomism, strictly speaking, and this school of thought has in any event been far more influential among theologians than among philosophers."<ref name=:0/>

===Lublin Thomism<!--'Lublin Thomism' and 'Phenomenological Thomism' redirect here-->===
'''Lublin Thomism''',<ref name=:0/> which derives its name from the [[Catholic University of Lublin]] in Poland where it is centered, is also sometimes called "'''phenomenological Thomism'''."<ref name=:0/> Like transcendental Thomism, it seeks to combine Thomism with certain elements of modern philosophy. In particular, it seeks to make use of the [[Phenomenology (philosophy)|phenomenological]] method of philosophical analysis associated with [[Edmund Husserl]] and the [[ethical personalism]] of writers like [[Max Scheler]] in articulating the Thomist conception of the human person. Its best-known proponent is [[Karol Wojtyla]] (1920–2005), who went on to become Pope John Paul II.<ref name=:0/>

However, unlike transcendental Thomism, the metaphysics of Lublin Thomism places priority on existence (as opposed to essence), making it an existential Thomism that demonstrates consonance with the Thomism of Étienne Gilson. The phenomenological concerns of the Lublin school are not metaphysical in nature as this would constitute [[idealism]]. Rather, they are considerations which are brought into relation with central positions of the school, such as when dealing with modern science, its epistemological value, and its relation to metaphysics.<ref name="Jaroszynski">{{cite web |url=http://www.hyoomik.com/lublin/jarosz1.html |title=A Brief Overview of Lublin Thomism |publisher=Hyoomik.com |access-date=20 November 2011 |url-status=dead |archive-url=https://web.archive.org/web/20120310194904/http://www.hyoomik.com/lublin/jarosz1.html |archive-date=10 March 2012}}</ref>

===Analytical Thomism===
{{Main|Analytical Thomism}}
[[Analytical Thomism]]<ref name=:0/> described by [[John Joseph Haldane|John Haldane]], its key proponent, as "a broad philosophical approach that brings into mutual relationship the styles and preoccupations of recent English-speaking philosophy and the concepts and concerns shared by Aquinas and his followers" (from the article on "analytical Thomism" in ''The Oxford Companion to Philosophy'', edited by Ted Honderich). By "recent English-speaking philosophy" Haldane means the [[Analytical philosophy|analytical tradition]] founded by thinkers like [[Gottlob Frege]], [[Bertrand Russell]], [[G. E. Moore]], and [[Ludwig Wittgenstein]], which tends to dominate academic philosophy in the English-speaking world. [[Elizabeth Anscombe]] (1919–2001) and her husband [[Peter Geach]] are sometimes considered the first "analytical Thomists", though (like most writers to whom this label has been applied) they did not describe themselves in these terms, and as Haldane's somewhat vague expression "mutual relationship" indicates, there does not seem to be any set of doctrines held in common by all analytical Thomists. What they do have in common seems to be that they are philosophers trained in the analytic tradition who happen to be interested in Aquinas in some way; and the character of their "analytical Thomism" is determined by whether it tends to stress the "analytical" side of analytical Thomism, or the "Thomism" side, or, alternatively, attempts to emphasize both sides equally.<ref name="Feser2">{{cite web|author=Edward Feser |title=The Thomistic tradition, Part II|url=http://edwardfeser.blogspot.com/2009/10/thomistic-tradition-part-ii.html|date=18 October 2009|access-date=2011-01-02|url-status=live|archive-url=https://web.archive.org/web/20101129012252/http://edwardfeser.blogspot.com/2009/10/thomistic-tradition-part-ii.html|archive-date=29 November 2010|author-link=Edward Feser}}</ref><ref>[https://www.ashgate.com/pdf/SamplePages/Analytical_Thomism_Intro.pdf The introduction] {{webarchive |url=https://web.archive.org/web/20110526201136/https://www.ashgate.com/pdf/SamplePages/Analytical_Thomism_Intro.pdf |date=26 May 2011 }} to [https://www.worldcat.org/oclc/61211285 Paterson & Pugh's book on Analytical Thomism] {{webarchive|url=https://web.archive.org/web/20160404000911/http://www.worldcat.org/title/analytical-thomism-traditions-in-dialogue/oclc/61211285 |date=4 April 2016 }} is available gratis online.</ref>

== 24 Thomistic theses of Pius X ==
With the decree ''Postquam sanctissimus'' of 27 July 1914, [[Pope Pius X]] stated that 24 theses formulated by "teachers from various institutions [...] clearly contain the principles and more important thoughts" of Aquinas.<ref>[http://vaxxine.com/hyoomik/aquinas/theses.eht ''Postquam sanctissimus''] {{webarchive|url=https://web.archive.org/web/20070810225643/http://www.vaxxine.com/hyoomik/aquinas/theses.eht|date=10 August 2007}}, Latin with English translation

See also [http://www.u.arizona.edu/~aversa/scholastic/24Thomisticpart2.htm P. Lumbreras's commentary on the 24 Thomistic Theses] {{webarchive|url=https://web.archive.org/web/20110605055456/http://www.u.arizona.edu/~aversa/scholastic/24Thomisticpart2.htm|date=5 June 2011}}.</ref><ref>{{cite web|url=https://franciscan-archive.org/thomas/24theses.html|title=Sacred Congregation of Studies Decree of Approval of some theses contained in the Doctrine of St. Thomas Aquinas and proposed to the Teachers of Philosophy|date=July 27, 1914}}</ref>

On March 7, 1916, the Congregation of Studies, which in the meantime had become the Sacred Congregation of Seminaries and Universities, while confirming that the twenty-four theses did in fact express the authentic teaching of Saint Thomas, replied by ordering only that they be proposed by the professors to their students as safe rules of guidance.<ref>{{cite web|author=James A. Weisheipl, O.P.|url=http://www.domcentral.org/study/revival.htm|title=The revival of thomism. An historical survey|archive-url=https://archive.today/20250211212148/http://www.domcentral.org/study/revival.htm|archive-date=February 11, 2025|url-status=live}}</ref>

=== Ontology ===
{{See also|Ontology|Non-physical entity}}

# Potency and Act divide being in such a way that whatever is, is either [[Actus purus|pure act]], or of necessity it is composed of potency and [[Actus primus|act as primary]] and intrinsic principles.
# Since act is perfection, it is not limited except through a potency which itself is a capacity for perfection. Hence in any order in which an act is pure act, it will only exist, in that order, as a unique and unlimited act. But whenever it is finite and manifold, it has entered into a true composition with potency.
# Consequently, the one God, unique and simple, alone subsists in absolute being. All other things that participate in being have a nature whereby their being is restricted; they are constituted of essence and being, as really distinct principles.
# A thing is called a being because of "esse". God and creature are not called beings univocally, nor wholly equivocally, but analogically, by an analogy both of attribution and of proportionality.
# In every creature there is also a real composition of the subsisting subject and of added secondary forms, i.e. [[Accidental property|accidental]] forms. Such composition cannot be understood unless being is really received in an essence distinct from it.
# Besides the absolute accidents there is also the relative accident, relation. Although by reason of its own character relation does not signify anything inhering in another, it nevertheless often has a cause in things, and hence a real entity distinct from the subject.
# A spiritual creature is wholly simple in its essence. Yet there is still a twofold composition in the spiritual creature, namely, that of the essence with being, and that of the substance with accidents.
# However, the corporeal creature is composed of act and potency even in its very essence. These act and potency in the order of essence are designated by the names ''form'' and ''matter'' respectively.

=== Cosmology ===
{{See also|Cosmology (metaphysics)|l1=Cosmology}}

# Neither the matter nor the form have being of themselves, nor are they produced or corrupted of themselves, nor are they included in any category otherwise than reductively, as substantial principles.
# Although extension in quantitative parts follows upon a corporeal nature, nevertheless it is not the same for a body to be a substance and for it to be quantified. For of itself substance is indivisible, not indeed as a point is indivisible, but as that which falls outside the order of dimensions is indivisible. But quantity, which gives the substance extension, really differs from the substance and is truly an accident.
# The principle of individuation, i.e., of numerical distinction of one individual from another with the same specific nature, is matter designated by quantity. Thus in pure spirits there cannot be more than one individual in the same specific nature.
# By virtue of a body's quantity itself, the body is circumscriptively in a place, and in one place alone circumscriptively, no matter what power might be brought to bear.
# Bodies are divided into two groups; for some are living and others are devoid of life. In the case of the living things, in order that there be in the same subject an essentially moving part and an essentially moved part, the substantial form, which is designated by the name soul, requires an organic disposition, i.e. heterogeneous parts.

=== Psychology ===
{{See also|Psychology}}

# Souls in the vegetative and sensitive orders cannot subsist of themselves, nor are they produced of themselves. Rather, they are no more than principles whereby the living thing exists and lives; and since they are wholly dependent upon matter, they are incidentally corrupted through the corruption of the composite.
# On the other hand, the human soul subsists of itself. When it can be infused into a sufficiently disposed subject, it is created by God. By its very nature, it is incorruptible and immortal.
# This rational soul is united to the body in such a manner that it is the only substantial form of the body. By virtue of his soul a man is a man, an animal, a living thing, a body, a substance and a being. Therefore, the soul gives man every essential degree of perfection; moreover, it gives the body a share in the act of being whereby it itself exists.
# From the human soul there naturally issue forth powers pertaining to two orders, the organic and the non-organic. The organic powers, among which are the senses, have the composite as their subject. The non-organic powers have the soul alone as their subject. Hence, the intellect is a power intrinsically independent of any bodily organ.
# Intellectuality necessarily follows upon immateriality, and furthermore, in such manner that the further the distance from matter, the higher the degree of intellectuality. Any being is the adequate object of understanding in general. But in the present state of union of soul and body, quantities abstracted from the material conditions of individuality are the proper object of the human intellect.
# Therefore, we receive knowledge from sensible things. But since sensible things are not actually intelligible, in addition to the intellect, which formally understands, an active power must be acknowledged in the soul, which power abstracts intelligible likeness or species from sense images in the imagination.
# Through these intelligible likenesses or species we directly know universals, i.e. the natures of things. We attain to singulars by our senses, and also by our intellect, when it beholds the sense images. But we ascend to knowledge of spiritual things by analogy.
# The will does not precede the intellect but follows upon it. The will necessarily desires that which is presented to it as a good in every respect satisfying the appetite. But it freely chooses among the many goods that are presented to it as desirable according to a changeable judgment or evaluation. Consequently, the choice follows the final practical judgment. But the will is the cause of it being the final one.

=== God ===
{{See also|God}}

# We do not perceive by an immediate intuition that God exists, nor do we prove it ''[[A priori and a posteriori|a priori]]''. But we do prove it ''[[Empirical evidence|a posteriori]]'', i.e., from the things that have been created, following an argument from the effects to the cause: namely, from things which are moved and cannot be the adequate source of their motion, to a first unmoved mover; from the production of the things in this world by causes subordinated to one another, to a first uncaused cause; from corruptible things which equally might be or not be, to an absolutely necessary being; from things which more or less are, live, and understand, according to degrees of being, living and understanding, to that which is maximally understanding, maximally living and maximally a being; finally, from the order of all things, to a [[Active intellect|separated intellect]] which has ordered and organized things, and directs them to their end.
# The metaphysical motion of the Divine Essence is correctly expressed by saying that it is identified with the exercised actuality of its own being, or that it is subsistent being itself. And this is the reason for its infinite and unlimited perfection.
# By reason of the very purity of His being, God is distinguished from all finite beings. Hence it follows, in the first place, that the world could only have come from God by creation; secondly, that not even by way of a miracle can any finite nature be given creative power, which of itself directly attains the very being of any being; and finally, that no created agent can in any way influence the being of any effect unless it has itself been moved by the first Cause.

==Criticism==
In 1277, [[Étienne Tempier]], the [[Roman Catholic Archdiocese of Paris|bishop of Paris]] who had condemned the studying of [[Aristotelian logic]] by Christian theologians in 1270, issued another more extensive condemnation. One aim of this condemnation was to clarify that God's absolute power transcended any principles of logic that [[Aristotle]] or [[Averroes]] might place on it.<ref>{{Cite book |title=The Foundations of Modern Science in the Middle Ages: Their Religious, Institutional, and Intellectual Contexts |last=Grant |first=Edward |publisher=Cambridge University Press |year=1996 |isbn=0-521-56762-9 |pages=81–82}}</ref> More specifically, it contained a list of 219 propositions, including twenty Thomistic propositions, that the bishop had determined to violate the omnipotence of God. However Tempier's condemnation of Thomism was withdrawn after the [[canonization of Thomas Aquinas]]. 

Thomism has also been criticised in the [[Eastern Orthodox Church]] for giving greater importance to the works of [[Virtuous pagan|virtuous pagans]] like [[Plato]] and Aristotle over that of the [[Church Fathers]]. [[Prochoros Kydones]], a Greek scholar from the monastic brethren of [[Great Lavra]] who [[Hesychast controversy|opposed]] the [[Palamism|teachings]] of [[Gregory Palamas]] on the basis of Thomism, was condemned at a Patriarchal Synod of 1368 organised by the [[Ecumenical Patriarch of Constantinople|Patriarch of Constantinople]] [[Philotheos Kokkinos]], where Thomism itself was also condemned.<ref>{{Cite book |last=Russell |first=Norman |title=Gregory Palamas: The Hesychast Controversy and the Debate with Islam |date=September 1, 2022 |publisher=Liverpool University Press |isbn=978-1802077476 |pages=413–415}}</ref> 

Speaking on the Thomistic interpretation of [[transubstantiation]], [[Eastern Orthodox theology|Eastern Orthodox theologian]] [[Vladimir Lossky]] states

{{Blockquote|Roman Catholicism rationalizes even the sacrament of the [[Eucharist]]: it interprets spiritual action as purely material and debases the sacrament to such an extent that it becomes in its view a kind of atomistic miracle. The Orthodox Church has no metaphysical theory of Transsubstantiation, and there is no need of such a theory. Christ is the Lord of the elements and it is in His power to do so that 'every thing, without in the least changing its physical substance' could become His Body. Christ's Body in the Eucharist is not physical flesh.|source={{harvnb|Lossky|1969|p= 87}} }}

In his ''[[Against Henry, King of the English]]'', Luther criticized a perceived use of the [[proof by assertion]] and a reliance on style over substance in the [[Summa Theologica#Structure|Thomist form of disputation]], which he alleged as being, "It seems so to me. I think so. I believe so." Luther also argued that the Thomist method led to shallowness among theological debates in England at the time.<ref>[http://anglicanhistory.org/lutherania/against_henry.html Martin Luther against Henry King of England] translated by the Rev. E. S. Buchanan, M.A., BSc New York: Charles A. Swift, 1928</ref>

Thomism was criticized by [[Bertrand Russell]] in ''[[A History of Western Philosophy]]'' (1946). Neo-Thomism has been criticized by [[Modernism in the Catholic Church|Catholic modernists]] such as [[George Tyrrell|George Tyrell]] and by supporters of the ''[[Nouvelle théologie]]''.

==See also==
{{Portal|Catholicism|Philosophy}}
{{div col|colwidth=35em}}
* [[List of works by Thomas Aquinas]]
* [[Theism]]
* [[Catholic theology]]
* {{slink|Criticism of the Catholic Church#Nature of theology}}
* [[Brian Davies (philosopher)|Brian Davies]]
* [[Peter Kreeft]]
* [[Brian Leftow]]
* [[List of Thomist writers (13th–18th centuries)]]
* [[Alasdair MacIntyre]]
* [[Rule according to higher law]]
* [[Rule of law]]
* [[School of Salamanca]]
* ''[[The Thomist]]''
* [[Thomistic sacramental theology]]
* [[Thomistic Institute]]
{{div col end}}

==References==
{{Reflist|colwidth=30em}}

== Further reading ==
* [http://www.ewtn.com/library/theology/reality.htm ''Reality: A Synthesis of Thomistic Thought''] by [[Reginald Garrigou-Lagrange]]
*{{Cite book
| isbn = 9781304416186
| last = Garrigou-Lagrange
| first = Réginald
| author-link = Reginald Garrigou-Lagrange
| title = The Essence & Topicality of Thomism
| year = 2013
| publisher = Lulu.com
| url = http://216.27.62.241/shop/réginald-garrigou-lagrange-op/the-essence-topicality-of-thomism/hardcover/product-21199740.html
| archive-url = https://archive.today/20130912022338/http://216.27.62.241/shop/r%C3%A9ginald-garrigou-lagrange-op/the-essence-topicality-of-thomism/hardcover/product-21199740.html
| url-status = dead
| archive-date = 12 September 2013
}}
* [[iarchive:modernthomisticp01phil|''Modern Thomistic Philosophy'']] by Richard Percival Phillips, an introduction on the Thomistic philosophy of nature
* [https://www.ashgate.com/pdf/SamplePages/Analytical_Thomism_Intro.pdf Introductory chapter by Craig Paterson and Matthew Pugh on the development of Thomism]
* [https://web.archive.org/web/20110217171955/http://www.vaxxine.com/hyoomik/aquinas/theses.eht The XXIV Theses of Thomistic Philosophy] and [http://scholastic.us.to/24Thomisticpart2.htm commentary by P. Lumbreras, O.P.]

==External links==
*{{in lang|la}} [http://www.corpusthomisticum.org/ Corpus Thomisticum] – Aquina's complete works
* [https://web.archive.org/web/20110605003223/http://www.corpusthomisticum.org/bt/index.html Bibliographia Thomistica]
* [https://www.apronus.com/theology/thomas-aquinas-emulator Thomas Aquinas Emulator Project], research into the use of generative AI to emulate Thomas Aquinas for an interactive engagement with Thomism

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