Dicisigns - the Actuality of Peirce's Theory of Propositions
Peirce's theory of propositions has been strangely neglected in comparison to icons-indices-symbols or other among his semiotic distinctions - maybe because of the fact that semiotics has too often left the notion of truth to logic and epistemology. But Peirce's account for propositions differs crucially from the Frege-Russell-Wittgenstein tradition with its emphasis on language - as I argue in "Natural Propositions" (Boston: Docent Press 2014).
Peircean propositions are functionally defined - they comprise all signs with simultaneously describe and refer to one and the same object. This double function is what makes truth possible - if the description fits the object referred to, the claim is true. But the important actuality of the doctrine lies in the fact that this vastly extends the received notion of propositions in two directions. One is to biosemiotics - to biological signs with the crucial double function, like firefly signaling. In some sense it is not strange that animal signs able to state truths would adapt better than signs without this ability. Another extension is to pictures, gestures, diagrams etc which may also claim truth - often in hybrid collaborations with language.
Peircean propositions, to sum up, are central to cognitive semiotics.