As nouns the difference between inferentialism and inferentialist
is that inferentialism
is (philosophy) inferential role semantics: an approach to the theory of meaning that identifies the meaning of an expression with its (typically inferential) relationship to other expressions while inferentialist
is a supporter of inferentialism.
As an adjective inferentialist is
(philosophy|semantics) of, pertaining to or supporting a belief in the primary importance of inference to any account of meaning.