Full Idea
Putnam replaces a correspondence theory of truth with an epistemic notion of truth - truth is idealized rational acceptability. The correspondence theory is committed to realism, but his allows ontological relativism.
Gist of Idea
Putnam's epistemic notion of truth replaces the realism of correspondence with ontological relativism
Source
report of Hilary Putnam (Reason, Truth and History [1981]) by Paul O'Grady - Relativism Ch.3
Book Reference
O'Grady,Paul: 'Relativism' [Acumen 2002], p.73
A Reaction
This seems to be part of a slide by Putnam away from realism towards pragmatism. As a robust and defiant realist, this always strikes me as the road to hell.