The paper is sympathetic to the idea that speakers have implicit knowledge of the semantics of sub-sentential elements of language, loosely, of words. Implicit knowledge is knowledge which the subject need not be capable of articulating yet which is a genuine propositional attitude and it is to be contrasted with tacit knowledge which refers to an information-bearing state which, however, is not a genuine propositional attitude. I begin by defending the implicit knowledge conception of speakers' knowledge of the meanings of (...) words from a challenge articulated by Evans and then go on the offensive against positions which attempt to replace the notion of implicit knowledge in semantic theory by that of tacit knowledge. (shrink)