Full Idea
It may be that where there are no positive grounds for a charge of irrationality, the acceptance of a belief with only external justification is still subjectively irrational in a sense that rules out its being epistemologically justified.
Gist of Idea
Even if there is no obvious irrationality, it may be irrational to base knowledge entirely on external criteria
Source
Laurence Bonjour (Externalist Theories of Empirical Knowledge [1980], §IV)
Book Reference
'Epistemology: Internalism and Externalism', ed/tr. Kornblith,Hilary [Blackwell 2001], p.20
A Reaction
A key objection. Surely rational behaviour requires a judgement to be made before a belief is accepted? If you are consistently clairvoyant, you must ask why.