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Single Idea 8492

[filed under theme 5. Theory of Logic / E. Structures of Logic / 6. Relations in Logic ]

Full Idea

Functions of one argument are concepts; functions of two arguments are relations.

Gist of Idea

Relations are functions with two arguments

Source

Gottlob Frege (Function and Concept [1891], p.39)

Book Ref

Frege,Gottlob: 'Translations from the Writings of Gottlob Frege', ed/tr. Geach,P/Black,M [Blackwell 1980], p.39


A Reaction

Nowadays we would say 'two or more'. Another interesting move in the aim of analytic philosophy to reduce the puzzling features of the world to mathematical logic. There is, of course, rather more to some relations than being two-argument functions.


The 11 ideas with the same theme [role of terms which connect objects into relationships]:

De Morgan found inferences involving relations, which eluded Aristotle's syllogistic [De Morgan, by Hart,WD]
De Morgan started the study of relations and their properties [De Morgan, by Walicki]
The logic of relatives relies on objects built of any relations (rather than on classes) [Peirce]
Relations are functions with two arguments [Frege]
In 'Principia' a new abstract theory of relations appeared, and was applied [Russell/Whitehead, by Gödel]
All relations, apart from ancestrals, can be reduced to simpler logic [Quine]
We can use mereology to simulate quantification over relations [Lewis]
Relations need terms, so they must be second-order entities based on first-order tropes [Campbell,K]
A relation is either a set of sets of sets, or a set of sets [Burgess/Rosen]
The mathematics of relations is entirely covered by ordered pairs [Chihara]
'Before' and 'after' are not two relations, but one relation with two orders [Hossack]