A concrete proposal is presented as to how semantics should be naturalized. Rather than attempting to naturalize propositions, they are treated as abstract entities that index concrete cognitive states. In turn the relevant concrete cognitive states are identified via perceptual classifications of worldly states, with the aid of an interactive theory of perception. The approach enables a broadly realist theory of propositions, truth and cognitive states to be preserved, with propositions functioning much as abstract mathematical constructs do in the nonsemantic (...) sciences, but with a much more specific propositional indexing scheme than previous naturalistic proposals were able to achieve. (shrink)