 How might a physicalist respond to Kripke’s argument? As with the knowledge argument, there are many responses but here I will mention only two. The first response is to insist that Kripke’s argument neglects the distinction between a priori and a posteriori physicalism. Kripke often does say that according to the dispositionalist, one should be able to ‘read off’ truths about meaning from truths a physicalist can accept. (For a proposal like this, see Horwich 2000.) One problem with this proposal is, as we have seen, that its background account of the necessary a posteriori is controversial. As we saw, a posteriori physicalists are committed to what we called the non-derivation view about necessary a posteriori truths. But the non-derivation view has come under attack in recent times.