Full Idea
What the relativist fails to see is that it is a presupposition of thought itself that some kind of objective 'rightness' exists.
Gist of Idea
Some kind of objective 'rightness' is a presupposition of thought itself
Source
Hilary Putnam (Reason, Truth and History [1981], Ch.5)
Book Reference
Putnam,Hilary: 'Reason, Truth and History' [CUP 1998], p.124
A Reaction
This may be the key objection to relativism. If you have a frame of reference, is it a good one? If you have a new perspective, is it better than your old one? Is the culture you live in confused or clear-thinking? Jokes and metaphors rely on truth.