Page "Physicalism" Paragraph 20

Hempel's Dilemma attacks how physicalism is defined.

One could either define the physical with respect to the entities stipulated by contemporary physics or with respect to some future complete physics.

Both options seem problematic.

In the first case, it seems reasonable to assume ( based on the history of science ) that current physical theories will very probably be refined by future scientific discoveries.

Therefore, it is very likely that any definition of " the physical " based on the current state of physics would end up being ultimately false.

If on the other hand, we define the notion of what is physical based some future idealized physics, we have not effectively defined anything at all because nobody knows what entities a future physical theory might postulate.