On pragmatic presupposition

I argue that (a) the phenomenon characteristic of pragmatic presupposition, is distinct from (b) the phenomenon characteristic of semantic presupposition, and that there are sentences exhibiting (a) alone. I apply this to Stalnaker's defense of van Fraassen's theory of semantic presupposition against Karttunen. I show that, since Stalmaker fails to distinguish (a) from (b), this defense amounts to an unsuccessful attempt to explain pragmatically the supposed instances of (b) in Karttunen's counter-examples. I observe that, given the distinction between (a) and (b), we can salvage from Stalnaker the strategy of discounting certain of Karttunen's counter-examples which exhibit not (b) but merely (a).