Full Idea
It is possible to conceive of one understanding the meaning of a realm of ideas, but holding that one cannot judge as to the truth or rationality of the claims made in it.
Gist of Idea
One may understand a realm of ideas, but be unable to judge their rationality or truth
Source
Paul O'Grady (Relativism [2002], Ch.5)
Book Reference
O'Grady,Paul: 'Relativism' [Acumen 2002], p.158
A Reaction
I think Davidson gives good grounds for challenging this, by doubt whether one 'conceptual scheme' can know another without grasping its rationality and truth-conditions.