  The Sorites is a particularly lethal weapon when used in the field of semantics, threatening to erase the boundaries on which rigid definitions depend. It may be relevant, then, that Diodorus is reported to have propounded a semantic theory of his own (Aulus Gellius, Attic nights 11.12.1–3; cf. 1 above, the story of his renaming his slave, reported by Ammonius, On Aristotle’s De interpretatione 38.17–20). This was based on the ‘conventionalist’ thesis expressed by the character Hermogenes in Plato’s Cratylus, according to whom nothing but convention—whether national, local or simply private—determines the meaning of a word, and any convenient string of sounds can in principle be used to convey any meaning. Diodorus’s inference from this was that the sole determinant of any word’s meaning is the intention of the utterer on any given occasion on which it is used. He went on to infer that there are no actual ambiguities: given the assumption that a word is on each occasion uttered with one specific meaning in mind, a word has only one meaning at any time.