One the other hand, if physicalism is true, and S summarizes the total nature of the world then S# is already implicitly included in S. In other words, (15) is simply an expansion of (14). But if (15) is just an expansion of (14), then if (15) is a priori, (14) must also be a priori. But that means our initial assumption is false: (14) is not a necessary a posteriori truth after all (see Jackson 1998).