Some physical theories predict that almost all brains in the universe are Boltzmann brains, i.e. short-lived disembodied brains that are accidentally assembled as a result of thermodynamic or quantum fluctuations. Physicists and philosophers of physics widely regard this proliferation as unacceptable, and so take its prediction as a basis for rejecting these theories. But the putatively unacceptable consequences of this prediction follow only given certain philosophical assumptions. This paper develops a strategy for shielding physical theorizing from the threat of Boltzmann (...) brains. The strategy appeals to a form of phenomenal externalism about the physical basis of consciousness. Given that form of phenomenal externalism, the proliferation of Boltzmann brains turns out to be benign. While the strategy faces a psychophysical fine-tuning problem, it both alleviates cosmological fine-tuning concerns that attend physics-based solutions to Boltzmann brain problems and pays explanatory dividends in connection with time’s arrow. (shrink)

Experiences tend to be followed by states for which they provide normative reasons. Such harmonious correlations cry out for explanation. Theories that answer or diminish these cries thereby achieve an advantage over theories that do neither. I argue that the main lines of response to these cries that are available to biological theorists—theorists who hold (roughly) that conscious subjects are generally biological entities—are problematic. And I argue that panpsychism—which holds (roughly) that conscious subjects are ubiquitous in nature—provides an attractive response (...) to these explanatory cries. Taken together, these considerations underwrite a kind of ‘psychophysical fine-tuning’ argument in support of panpsychism, one that is reminiscent of cosmological fine-tuning arguments in favor of multiverse hypotheses. (shrink)