 W. Davis (2016a: §5.3) replies as follows.  A speaker who used  (15a)  to mean  [15b]  would just as naturally use (16a) to mean [16b], and hearers would understand the speaker accordingly. But what the speaker said is not entailed by [16b]. What the speaker of (16a) said would be false in circumstances in which Alice was unlikely to jump off the cliff if she jumped. Hearers would focus on what the speaker meant, though, which would be true even in those circumstances. Since the speaker meant one thing [16b] by saying something else [16a], the speaker implicates [16b]. The speaker does not implicate anything by uttering the antecedent of (16a). The speaker says something only by uttering the whole conditional. So there is really no embedding of implicatures when (16a) is uttered. The relationship between  (15)  and (16) is special. In many other cases in which a sentence “p” conversationally implicates “q”, the conditional “If p then r” does not implicate “If p and q then r”. For example, If Bill got some problems wrong, he might have gotten them all wrong does not implicate “If Bill got some but not all problems wrong, he might have gotten them all wrong”.