If you accept some versions of panpsychism, then you think that everything in the Universe contains a latent grain of consciousness. So is Colin the Rock conscious? If so, can you think of a test to empirically demonstrate this? In other versions of panpsychism, such as the variant proposed by Alfred North Whitehead, Colin is not conscious because he’s an aggregate object and not a true individual, but the atoms of which he’s composed can be said to be individuals and therefore be composed of ‘moments of experience.’ Therefore, Colin's atoms can have crude experiences. Again, how might this be empirically demonstrated?
If, on the other hand, you think that Colin does not or cannot have even the dimmest spark of consciousness, how could you demonstrate that? One might say that the burden of proof lies with those who claim that Colin has experiences, and that the principle of parsimony suggests that, all things being equal, one shouldn’t assume something has invisible attributes without a good reason. But if you think this, how do you respond to Galen Strawson’s arguments that physicalism entails panpsychism?
Or you might decide to use Popper and the positivist’s principle of falisifiability i.e. claim that a theory can only be scientific if it is falsifiable. Since we cannot falsify the claim that Colin is dimly conscious (or that Colin entirely lacks consciousness, for that matter), both theories are, according to the positivists, essentially meaningless.
But if this is so, then this places a strict limit on the scientific search for consciousness. If a bacterium possesses conscious awareness, but we also cannot prove it, then that’s surely an important fact about nature we’re neglecting. We should also recall that this sort of reasoning is exactly what led a number of behaviourists to ignore human minds and consciousness for half a century….