A Bayesian Spirit Catcher
Since my recent posts on material and spiritual explanations have been so egregiously misunderstood by some commenters, let me try again, with a new tack. Bayesian inference is given by the rule: Our H is: "Hildegard of Bingen had visions sent from God." Our E is that we discover that Hildegard was suffering from migraines. (By the way, this idea is just sheer speculation on the part of Oliver Sacks, with little evidence behind it. But let us imagine it confirmed.) Let us say someone like my friend Ben Kay has the prior P(H) that Hildegard experienced divine visions of 0. (Ben is a committed atheist.) Then E arrives. Ben touts it as, "See, she just had migraines." But this is insincere: with a P(H) of 0, for any evidence that arrives, Ben will have a P(H | E) of 0! I have another friend, an Inuit fellow named Nahallak, who thinks Hildegard's life story makes her report of divine visions likely, so that he has a P(H) of .8. But he is also...