Full Idea
We cannot determine what someone's beliefs are independently of assessing to some extent the truth or falsity of the beliefs.
Gist of Idea
We must assess the truth of beliefs in identifying them
Source
W.H. Newton-Smith (The Rationality of Science [1981], X.4)
Book Reference
Newton-Smith,W.H.: 'The Rationality of Science' [RKP 1981], p.249