 The appeal to the necessary a posteriori is on the surface an attractive one, but it is also controversial. One problem arises from the fact that Kripke’s idea that there are necessary and a posteriori truths can be interpreted in two rather different ways. On the first interpretation — I will call it the derivation view — while there are necessary a posteriori truths, these truths can be derived a priori from truths which are a posteriori and contingent. On the second interpretation — I will call it the non-derivation view — there are non-derived necessary a posteriori truths, i.e. necessary truths which are not derived from any contingent truths (or any a priori truths for that matter). The problem is that when one combines the derivation view with the claim that (14) is necessary and a posteriori, one encounters a contradiction. If the derivation view is correct, then there is some contingent and a posteriori statement S# that logically entails (14). However, if S# logically entails (14) then (since ‘If C, then if A then B’ is equivalent to ‘If C &amp; A, then B’) we can infer that the following is both necessary and a priori: