Foundationalism

Foundationalism concerns philosophical theories of knowledge resting upon justified belief, some secure foundation of certainty. Its main rival is coherentism, whereby a body of knowledge, not requiring a secure foundation, can be established by the interlocking strength of its components, like a puzzle solved without prior certainty that each small region was solved correctly.

Identifying the other options to be either circular reasoning or infinite regress, thus the regress problem, Aristotle found the clear choice to be foundationalism, which posits basic beliefs underpinning others.Descartes, the most famed foundationalist, discovered a foundation in the fact of his own existence and the "clear and distinct" ideas of reason, whereas Locke saw foundation in experience. A foundation reflects differing epistemological emphases—empiricists emphasizing experience, rationalists emphasizing reason—but may blend both.

In the 1930s, debate over foundationalism revived. Whereas Schlick viewed scientific knowledge like a pyramid where a special class of statements does not require verification through other beliefs and serves as a foundation, Neurath argued that scientific knowledge lacks an ultimate foundation and acts like a raft. In the 1950s, foundationalism fell into decline largely via Quine, whose ontological relativity found any belief networked to one's beliefs on all of reality, while auxiliary beliefs somewhere in the vast network are readily modified to protect desired beliefs.