Foundationalism's any theory in epistemology (typically, theories of justification, but also of knowledge) that holds that beliefs are justified (known, etc.) based on what're called basic beliefs (also commonly called foundational beliefs). Basic beliefs are beliefs that give justificatory support to other beliefs, and more derivative beliefs are based on those more basic beliefs. The basic beliefs are said to be self-justifying or self-evident, that's, they enjoy a non-inferential warrant (or… (More on Foundationalism)