Full Idea
If I say this is green, I must say that other things are green too. I am committed to a future usage.
Gist of Idea
Using 'green' is a commitment to future usage of 'green'
Source
Ludwig Wittgenstein (Lectures 1930-32 (student notes) [1931], B VI.2)
Book Reference
Wittgenstein,Ludwig: 'Lectures in Cambridge 1930-32', ed/tr. Lee,Desmond [Blackwell 1980], p.37
A Reaction
This seems to suggest that the eternal verity of a universal concept is just a convention of stability in a language.