What is the Relation between Semantic and Substantive Epistemic Contextualism?

Epistemic Contextualism is generally treated as a semantic thesis that may or may not have epistemological consequences. It is sometimes taken to concern only knowledge claims (as the assertion that the word “know” means different things in different contexts of use). Still, at other times it is taken to regard the knowledge relation itself (as the assertion that knowledge itself has no single univocal nature). Call the former view Semantic EC, the latter view Substantive EC, and the idea that the plausibility of Semantic EC presupposes that of Substantive EC, the “Presupposition Thesis.” Numerous authors argue against the Presupposition Thesis on the grounds that an understanding of the nature of knowledge is no more required to understand the meaning of knowledge assertions than an understanding of the self, for instance, is needed to understand the meaning of sentences containing “I.” These authors then offer additional arguments for the same conclusion, using further comparisons between “know” and other indexicals, as well as between “know” and quantifiers, gradable and modal adjectives. Herein, I defend the Presupposition Thesis by arguing against these authors’ claims (based as they are on these types of comparisons) that Semantic EC is plausible without the supposition of Substantive EC.