{"id":95,"date":"2006-12-20T17:35:00","date_gmt":"2006-12-20T21:35:00","guid":{"rendered":"http:\/\/alanrhoda.net\/wordpress\/?p=95"},"modified":"2006-12-20T17:35:00","modified_gmt":"2006-12-20T21:35:00","slug":"bart-ehrman-on-history-and-miracles","status":"publish","type":"post","link":"http:\/\/alanrhoda.net\/wordpress\/2006\/12\/bart-ehrman-on-history-and-miracles\/","title":{"rendered":"Bart Ehrman on History and Miracles"},"content":{"rendered":"

I’m just about finished listening to an audio CD lecture series entitled “The Historical Jesus”<\/a> by Bart Ehrman. It’s an interesting series by a scholar who, I gather, represents more-or-less a mainstream position in biblical scholarship. In other words, Ehrman is neither an out-and-out debunker of orthodox Christianity nor an out-and-out advocate and apologist. Rather, he styles himself as a professional “historian” and limits himself to what he thinks can be established with reasonable historical certainty. The result is that Ehrman accepts much of the New Testament account of the life of Jesus, but also rejects significant parts of the account.<\/p>\n

As for the miracles attributed to Jesus, Ehrman neither affirms nor denies them. Rather, he invokes a kind of “historian’s privilege”, arguing that as a historian<\/span> he cannot, in principle, affirm that a miracle, any miracle, has occurred in the past. Here’s where I was most disappointed with Ehrman, because his a priori <\/span>justification of this agnostic stance rests on what stikes me as a transparently fallacious argument. Here, in a nutshell, is his case:<\/p>\n

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  1. It is the job of the professional historian to determine what probably<\/span> happened in the past.<\/li>\n
  2. Miracles are, by definition, improbable<\/span>.<\/li>\n
  3. Therefore, the professional historian cannot as such affirm that a miracle has occurred.<\/li>\n<\/ol>\n

    The problem with this argument is the Ehrman conflates prior probabilities<\/span> with posterior probabilities<\/span>. The sense in which miracles are definitionally “improbable” according to premise 2 has to do with their having a low prior probability. In other words, miracles are not the sort of things that, given our usual background assumptions about the world, could be predicted in advance<\/span>. Instead, we would expect under normal conditions that miracles would not<\/span> happen. But the sense in which it is the job of the historian to determine what “probably” happened according to premise 1 has to do with posterior probabilities, that is, with the probability of a given reconstruction of events in the light of<\/span><\/span> all of the available historical evidence. Since the relevant sense of “probability” shifts from premise 1 to premise 2, Ehrman’s argument commits the fallacy of equivocation, and is therefore invalid.<\/p>\n

    Let me put my point more precisely with the help of Bayes’ Theorem, which is provably true given the standard axioms of probability theory and widely used in philosophy of science as a model for evaluating the degree of support given to a hypothesis by new evidence.<\/p>\n