View source for Type–token distinction

{{Short description|Distinguishing objects and classes of objects}}
[[File:Flock of birds at Rome.ogg|right|300px|thumb|Although this flock is made of the same ''type'' of bird, each individual bird is a different ''token''.|thumbtime=6]]

The '''type–token distinction''' is the difference between a '''''type''''' of objects (analogous to a [[Class (philosophy)|''class'']]) and the individual '''''tokens''''' of that type (analogous to [[Instantiation principle|''instances'']]). Since each type may be instantiated by multiple tokens, there are generally more tokens than types of an object. 

For example, the sentence "A Rose is a rose is a rose" contains three word types: three word tokens of the type ''a'', two word tokens of the type ''is,'' and three word tokens of the type ''rose''. The distinction is important in disciplines such as [[logic]], [[linguistics]], [[metalogic]], [[typography]], and [[computer programming]].

==Overview==
The type–token distinction separates ''types'' (abstract descriptive concepts) from ''tokens'' (objects that instantiate concepts). For example, in the sentence "''the bicycle is becoming more popular''" the word ''bicycle'' represents the abstract concept of bicycles and this abstract concept is a type, whereas in the sentence "''the bicycle is in the garage''", it represents a particular object and this particular object is a token. Similarly, the word type 'letter' uses only four letter types: ''L'', ''E'', ''T'' and ''R''. Nevertheless, it uses both ''E'' and ''T'' twice. One can say that the word type 'letter' has six letter tokens, with two tokens each of the letter types ''E'' and ''T''. Whenever a word type is inscribed, the number of letter tokens created equals the number of letter occurrences in the word type.

Some logicians consider a word type to be the class of its tokens. Other logicians counter that the word type has a permanence and constancy not found in the class of its tokens. The type remains the same while the class of its tokens is continually gaining new members and losing old members.{{fact|date=November 2022}}

== Typography ==
In [[typography]], the type–token distinction is used to determine the presence of a text printed by [[movable type]]:<ref>[[Herbert E. Brekle|Brekle, Herbert E.]]: ''Die Prüfeninger Weiheinschrift von 1119. Eine paläographisch-typographische Untersuchung'', Scriptorium Verlag für Kultur und Wissenschaft, Regensburg 2005, {{ISBN|3-937527-06-0}}, p.&nbsp;23</ref>

{{quote|The defining criteria which a typographic print has to fulfill is that of the type identity of the various [[letter form]]s which make up the printed text. In other words: each letter form which appears in the text has to be shown as a particular instance ("token") of one and the same type which contains a reverse image of the printed [[Letter (alphabet)|letter]].}}

== Charles Sanders Peirce ==
The distinctions between using words as types or tokens were first made by American logician and philosopher [[Charles Sanders Peirce]] in 1906 using terminology that he established.<ref>Charles Sanders Peirce, Prolegomena to an apology for pragmaticism, Monist, vol.16 (1906), pp. 492–546.</ref> Peirce's type–token distinction applies to words, sentences, paragraphs and so on: to anything in a universe of discourse of character-string theory, or [[concatenation theory]].

Peirce's original words are the following:

{{Quote|text=A common mode of estimating the amount of matter in a ... printed book is to count the number of words. There will ordinarily be about twenty 'thes' on a page, and, of course, they count as twenty words. In another sense of the word 'word,' however, there is but one word 'the' in the English language; and it is impossible that this word should lie visibly on a page, or be heard in any voice .... Such a ... Form, I propose to term a Type. A Single ... Object ... such as this or that word on a single line of a single page of a single copy of a book, I will venture to call a Token. .... In order that a Type may be used, it has to be embodied in a Token which shall be a sign of the Type, and thereby of the object the Type signifies.|author=Peirce 1906, also Ogden and Richards, 1923, 280-1.<ref>Ogden, C. K. & Richards, I. A. (1923). The meaning of meaning. London: Kegan Paul.</ref>}}

== See also ==
{{Div col|colwidth=22em}}
* {{annotated link|Class (philosophy)}}
* {{annotated link|Formalism (philosophy)}}
* {{annotated link|Haecceity}}
* {{annotated link|Hypernymy and hyponymy}}
* {{annotated link|Identity (philosophy)}}
* {{annotated link|Is-a}}
* {{annotated link|Map–territory relation}}
* {{annotated link|Mental model}}
* {{section link|Problem of universals|Peirce}}
* {{annotated link|Platonic ideal}}
* {{annotated link|Use–mention distinction}}
* {{annotated link|Type theory}}
* {{annotated link|Type physicalism}}
{{Div col end}}

==References==
{{reflist}}

===Sources===
*Baggin J. and Fosl P. (2003) ''The Philosopher's Toolkit''. Blackwell: 171-73. {{ISBN|978-0-631-22874-5}}.
*Peper F., Lee J., Adachi S., Isokawa T. (2004) ''Token-Based Computing on Nanometer Scales'', Proceedings of the ToBaCo 2004 Workshop on Token Based Computing, Vol.1 pp.&nbsp;1–18.

== External links ==
* {{Sep entry|types-tokens/| Types and Tokens|[[Linda Wetzel]]}}

{{Metalogic}}
{{Metaphysics}}
{{formal semantics}}

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