A belief is justified if the process that produced it reliably produces true beliefs

Alvin Goldman argued in 1979 that a belief is justified not because you can list reasons for it, but because a cognitive process that reliably generates true beliefs produced it, such as normal eyesight or sound memory. Looking at a tree and believing it's there is justified because vision reliably tracks reality, even if you can't articulate why you trust your eyes. Reliabilism sidestepped decades of debate over defining justification purely in terms of a believer's own internal reasons.

— Alvin I. Goldman, What Is Justified Belief? — In Justification and Knowledge, 1979