This paper argues that the problem of the apparent conflict between freedom of action and natural causal determinism has not been properly framed, because the key premiss—the thesis of universal causal determinism—is, in the domain of human behaviour, an unjustified conjecture based on over-simplified, under-informed explanatory models. Kant's semantics of singular cognitive reference, which stands independently of his Transcendental Idealism, justifies and emphasises a quadruple distinction between causal description, causal ascription, true causal ascription and cognitively justified causal ascription. Contemporary causal (...) theories of mind, of action or of meaning do not suffice for causal ascription, and so cannot suffice for causal predication, and hence cannot justify causal determinism about human behaviour. More generally, the principle of universal causal determinism is a regulative principle governing causal inquiry and was so formulated by LaPlace. Only successful, sufficient causal explanation of particular events provides for causal knowledge of those events. Such knowledge we lack in the domain of human behaviour. Rational belief, including scientific belief, requires apportioning belief to justifying evidence; all else is conjecture or speculation, which do not justify premises of sound proofs. Causal determinism about human behaviour remains unjustified speculation, for sound Critical reasons Kant provided us in the Kritik der reinen Vernunft. In these regards, contemporary debates about these issues remain decidedly pre-Critical. (shrink)