Classical foundationalism maintains that all knowledge and justified belief rest ultimately on a foundation of knowledge and justified belief that has not been inferred from other knowledge or belief. Because the classical foundationalist typically assumes an account of knowledge in terms of justified or rational true belief, it might be best to focus on the distinction invoked between inferentially and noninferentially justified beliefs. What is written in this entry will apply mutatis mutandis to the distinction between inferential and noninferential knowledge.

The Principle of Inferential Justification

If one thinks about most of the beliefs one takes to be justified and asks what justifies them, it seems natural to answer in terms of other justified beliefs. A person's justification for believing that it will rain, for example, may consist in part of that person's justifiably believing that the barometer is dropping rapidly. But under what conditions can...