Full Idea
An externalist theory of epistemic justification or warrant need not involve the possession by the believer of anything like a reason for thinking that their belief is true.
Gist of Idea
Externalist theories of justification don't require believers to have reasons for their beliefs
Source
Laurence Bonjour (In Defence of Pure Reason [1998], §3.7)
Book Reference
Bonjour,Laurence: 'In Defense of Pure Reason' [CUP 1998], p.96
A Reaction
That is the problem with externalism. If the believer does not have a reason, then why would they believe? Externalists are interesting on justification, but daft about belief. Why do I believe I know something, when I can't recall how I learnt it?