Hume Versus Price on Miracles and Prior Probabilities: Testimony and the Bayesian Calculation

Abstract

Hume's essay on miracles' is one of his most celebrated arguments. It is also, perhaps, the second most discussed and argued-over of his sceptical positions. Reading it in the light of a recent controversy over Bayesianism and the appropriateness of taking prior probabilities into account when judging the likelihood of an event's occurrence on the basis of reliable testimony2, I have been struck by the thought that Hume can best be seen as applying a proto-Bayesian argument to a celebrated eighteenth-century controversy. There is some evidence3 that it struck Hume's critics that way as well, yet none of the recent major commentators (e.g, Broad, Flew, Gaskin) mention Bayes4 or Hume's contemporary critic Richard Price, who most clearly discussed Hume's argument in this light. This is doubly unfortunate; not only does it make difficult a clear appreciation of what Hume was up to in the argument about miracles, but it also insulates the modem debate about prior probabilities from its history.5 In this paper I