The art of thinking · Concepts, categories and definition
Type–token distinction
Also known as: Types and tokens, Type and token, Type-token distinction
German: Type-Token-Unterscheidung
In philosophy and linguistics, the type–token distinction separates a general kind (the type) from its individual instances (the tokens); the terms were introduced by Charles Sanders Peirce, who noted that a page contains one word “the” as a type but many as tokens.
- Thinking models
- Philosophy
- Linguistics
In one sentence
A type is the general kind, a token one concrete instance of it — Peirce’s distinction, used from linguistics to data modeling.
Example
The manual describes the machine type PM-200; the service record describes the token with serial number 2041-117. A sentence that mixes both (“this machine was retrofitted”) leaves readers unsure which one is meant.
How it applies
- Peirce’s example: A page has perhaps twenty tokens of the word “the” but only one type. Peirce also used the word “tone” for a quality, giving the triad tone, token, type.
- Everywhere in modeling: Class and instance in object orientation, product type and serial unit in manufacturing, document type and document in markup languages all repeat the distinction.
- Counting depends on it: “How many words?” or “how many machines?” has two answers — types and tokens. Many misunderstandings are a type answer to a token question.
- Technical documentation: Instructions for use are written for a type; service, inspection and change records are about tokens. Metadata should say which of the two a piece of information is about, especially after modifications that make one unit differ from its type.
Type–token vs. class–instance
Class and instance are the type–token distinction applied to a formal model, where a class also defines the attributes its instances carry. Peirce’s distinction is broader: it covers words, signs and events, not only modeled objects.
How to read this pool
Entries, context cards and transitional topics
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