Single Idea 11100

[catalogued under 9. Objects / F. Identity among Objects / 1. Concept of Identity]

Full Idea

Frege's algorithm of identity is the law of putting equals for equals.

Gist of Idea

Frege's algorithm of identity is the law of putting equals for equals

Source

report of Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884]) by Willard Quine - Identity, Ostension, and Hypostasis 4

Book Reference

Quine,Willard: 'From a Logical Point of View' [Harper and Row 1963], p.76


A Reaction

Quine, and most modern philosophers, seem to accept universal substitutivity as a sufficient condition for identity. But you then get the problem of coextensionality (renate/cordate), which can only be solved by introducing modality.