Type–token distinction
The type–token distinction is the difference between a type of objects (analogous to a class) and the individual tokens of that type (analogous to 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.
Typography
In typography, the type–token distinction is used to determine the presence of a text printed by movable type:
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. 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:
See also
- Class (philosophy) – Philosophical term denoting a group of things derived from extensional or intensional definition
- Formalism (philosophy) – Concept of focusing on form over concept
- Haecceity – Term from medieval scholastic philosophy
- Hypernymy and hyponymy – Semantic relations involving the type-of property
- Identity (philosophy) – Relation each thing bears to itself alone
- Is-a – Subsumption relationship between abstractions
- Map–territory relation – Relationship between an object and a representation of that object
- Mental model – Mental representation of the external world
- Problem of universals § Peirce
- Platonic ideal – Philosophical theory attributed to Plato
- Use–mention distinction – Difference between using a word and mentioning it
- Type theory – Concept in mathematical logic
- Type physicalism – Theory in the philosophy of mind
References
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. 1–18.