ABSTRACT According to the so-called Hempel’s Dilemma, the thesis of physicalism is either false or empty. Our intention in this paper is not to propose a solution to the Dilemma, but rather to argue as follows: to the extent that Hempel’s Dilemma applies to physicalism it equally applies to any theory that gives a deep-structure and changeable account of our experience or of high-level theories. In particular, we will show that it also applies to mind–body dualistic theories. The scope of Hempel’s Dilemma turns out to be very wide: it is a special case of a general sceptical argument against changeable deep-structure theories in and outside science.