internalist

Holding that a particular mental phenomenon, such as motivation or justification, has an internal rather than external basis

For one thing, many people regard rationality as an epistemically internalist notion, whereas reliability is a paradigmatic example of an epistemically externalist notion.

A supporter of internalism

Perhaps I will appear presumptuous and misguided in claiming to explain the debate between internalists and externalists, for some would insist that there are a variety of related debates that get discussed under the heading of internalism and externalism.