WE think of our senses as hard-wired gateways to the world. Many years ago the social psychologist Daryl J. Bem described the knowledge we gain from our senses as “zero-order beliefs,” so taken for granted that we do not even notice them as beliefs. The sky is blue. The fan hums. Ice is cold. That’s the nature of reality, and it seems peculiar that different people with their senses intact would experience it subjectively.