more from André Gallois

Single Idea 16027

[catalogued under 9. Objects / F. Identity among Objects / 6. Identity between Objects]

Full Idea

The necessity of identity: a=b; □(a=a); so something necessarily = a; so something necessarily must equal b; so □(a=b). [A summary of the argument of Marcus and Kripke]

Gist of Idea

If two things are equal, each side involves a necessity, so the equality is necessary


André Gallois (Identity over Time [2011], §3)

Book Reference

'Stanford Online Encyclopaedia of Philosophy', ed/tr. Stanford University [], p.13

A Reaction

[Lowe 1982 offered a response] The conclusion seems reasonable. If two things are mistakenly thought to be different, but turn out to be one thing, that one thing could not possibly be two things. In no world is one thing two things!