The view in epistemology that knowledge must be regarded as a structure raised upon secure, certain foundations. These are found in some combination of experience and reason, with different schools (empiricism, rationalism) emphasizing the role of one over that of the other. Foundationalism was associated with the ancient Stoics, and in the modern era with Descartes, who discovered his foundations in the ‘clear and distinct’ ideas of reason. Its main opponent is coherentism, or the view that a body of propositions may be known without a foundation in certainty, but by their interlocking strength, rather as a crossword puzzle may be known to have been solved correctly even if each answer, taken individually, admits of uncertainty. See also coherence theory of truth, fallibilism, Neurath’s boat, protocol statements.