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Single Idea 8488

[filed under theme 18. Thought / D. Concepts / 3. Ontology of Concepts / c. Fregean concepts ]

Full Idea

A concept in logic is closely connected with what we call a function. Indeed, we may say at once: a concept is a function whose value is always a truth-value. ..I give the name 'function' to what is meant by the 'unsaturated' part.

Clarification

'Unsaturated' functions contain variables but not actual references

Gist of Idea

A concept is a function whose value is always a truth-value

Source

Gottlob Frege (Function and Concept [1891], p.30)

Book Ref

Frege,Gottlob: 'Translations from the Writings of Gottlob Frege', ed/tr. Geach,P/Black,M [Blackwell 1980], p.30


A Reaction

So a function becomes a concept when the variable takes a value. Problems arise when the value is vague, or the truth-value is indeterminable.


The 13 ideas from 'Function and Concept'

Frege thought traditional categories had psychological and linguistic impurities [Frege, by Rumfitt]
Frege takes the existence of horses to be part of their concept [Frege, by Sommers]
Frege allows either too few properties (as extensions) or too many (as predicates) [Mellor/Oliver on Frege]
Concepts are the ontological counterparts of predicative expressions [Frege, by George/Velleman]
Unlike objects, concepts are inherently incomplete [Frege, by George/Velleman]
An assertion about the concept 'horse' must indirectly speak of an object [Frege, by Hale]
I may regard a thought about Phosphorus as true, and the same thought about Hesperus as false [Frege]
A concept is a function whose value is always a truth-value [Frege]
Arithmetic is a development of logic, so arithmetical symbolism must expand into logical symbolism [Frege]
The concept 'object' is too simple for analysis; unlike a function, it is an expression with no empty place [Frege]
First-level functions have objects as arguments; second-level functions take functions as arguments [Frege]
The Ontological Argument fallaciously treats existence as a first-level concept [Frege]
Relations are functions with two arguments [Frege]