internalist adjective 1noun 1forms 3 adjective1 •Holding that a particular mental phenomenon, such as motivation or justification, has an internal rather than external basisFor one thing, many people regard rationality as an epistemically internalist notion, whereas reliability is a paradigmatic example of an epistemically externalist notion. — 2008 noun1 •A supporter of internalism formsinternalists · more internalist · most internalist