When dealing with ‘meaning’ or related notions, one cannot ignore what for a long time was the dominant paradigm in semantics. According to such paradigm, truth-conditional formal semantics for natural language is a theory of semantic competence. In this article, I shall discuss a foundational problem for such semantic program. I shall first be following authors who claim that truth-conditional formal semantics is unable to provide a complete account of lexical competence, and, therefore, it suffers from incompleteness. Moreover, as a (...) few authors observed, a coherent completion of lexical meaning/competence cannot be easily provided in the philosophical framework of truth-conditional semantics. The problem is a consequence of Kripke’s and Putnam’s arguments against the view that semantic values of words are cognitively determined. I shall argue that these arguments undermine the notion that formal semantics can be, at the same time, a theory of truth-conditions and a theory of semantic competence. I shall outline and critically discuss two general attempts to solve this problem, which I shall refer to as the social/ideal route and the concepts route. The conclusions of the article are deliberately open. I shall argue that both these attempts are exposed to conceptual troubles and counterintuitive consequences, and so the lexical problem still remains a deep and unresolved issue for semantics. (shrink)