Syntax precedes truth‐theoretic semantics when it comes to understanding a logical constant. A constant in a language is logical iff its sense is entirely constituted by certain deductive rules. To be sense‐constitutive, deductive rules governing a constant must meet certain conditions; those that do so are sense‐constitutive by virtue of understanders' conditional dispositions to feel compelled to accept certain formulae. Acceptance is a cognitive formula‐attitude. Since acceptance requires understanding, and a formula can contain more than one occurrence of logical constants, this account involves a ‘local holism’, but no circularity. I argue that no logical constant is ambiguous between a classical and a constructive sense; but I allow that one constant may have distinct classical and constructive ‘semantic values’. A logical constant's sense helps to determine its semantic value, but only together with certain constraints on satisfaction and frustration; it seems that the latter must include ‘convention T’‐style schemata.