  Here is it is helpful to examine Block’s Inverted Earth argument against functionalism, which at a superficial glance might not seem to stray beyond the constraints of Earthly biology. As we saw in subsection 2.3.3, the Inverted Earth scenario is designed to avoid certain objections to the usual argument from intrapersonal inversion hypotheses to interpersonal inversion hypotheses. How is the scenario turned into an argument against functionalism?