Full Idea
Externalist theories of knowledge are one species of foundationalism.
Clarification
'Foundational' theories base knowledge on something totally reliable
Gist of Idea
Externalist theories of knowledge are one species of foundationalism
Source
Laurence Bonjour (Externalist Theories of Empirical Knowledge [1980], Intro)
Book Reference
'Epistemology: Internalism and Externalism', ed/tr. Kornblith,Hilary [Blackwell 2001], p.10
A Reaction
I don't see why there shouldn't be a phenomenalist, anti-realist version of externalism, which just has 'starting points' instead of a serious commitment to foundations.