Thursday, July 28, 2011

Tim and Lydia McGrew on the Resurrection, part 8 (conclusion/outline)

[Continued from Part 7.]

I have tentatively argued for a Bayes factor of 106 given the textual assumptions of the McGrews. I have further proposed a way to expand the discussion to include skeptics of these assumptions. In these conclusions, I have agreed with the McGrews that their assumptions are plausible, and that on these assumptions the Resurrection is the best explanation. However, I think that they overreach when they claim, or seem to claim, that their methodology - which they agree is very partial - approximates a more general Bayes factor (p.39).

The rest of their paper (pp.46-68) discusses Hume and the objections of other apologists. As I have said, I am leaving that topic for later. Just as they have not claimed to have derived odds on the Resurrection, I do not claim to have done so either.

As I stated at the beginning, the McGrews have started an excellent conversation. I would recommend anyone who wishes to pursue a rigorous analysis of the evidence for the Resurrection to read their paper. And just as they have qualified, I must qualify that my approach has not been complete.

In particular, I have not gathered all of the relevant evidence in deriving this likelihood ratio. Many apologists insist on Paul's claim that there are 500 witnesses. Skeptics focus on potential `gaps' in the text, which become quite plausible on the (quite plausible) assumption that the relevant texts are polemical and designed to serve the Christian community. In this sense, my Bayes factor is not cumulative. My Bayes factor is also not cumulative with respect to textual criticisms. Again, I've outlined how that may be pursued. A fully rigorous analysis of all of the details will probably lead to a figure quite different from the one which I have suggested. But I think, quite plausibly, that the figure I have suggested is not a gross underestimate. And I think it quite low enough to leave anyone with a reasonable prior ratio unconvinced. If Christians think that the prior odds on the Resurrection are above something like 10-6, I hope they will tell me why this is. If they have such a value, I assume it will be within the context of a well-formed natural theology. Contrary to the McGrews (p.49), I think this will prove necessary.

So there are my efforts. I hope you will read them all before making critical comments, just as I hope you will read the McGrews' paper. If you spot a technical error or misspelling, I would of course appreciate immediate correction. Otherwise, I ask that you take time to absorb the details, and inquire for yourself how knowledge you have may further inform the discussion.

I also hope that readers can at least retrospectively appreciate the utility of Bayesian techniques in analyzing such arguments. The importance of this or that number is minimal: what is important is that they can be used to capture the arguments, show how they relate to each other, and help us to focus on the important details. They also help to understand how I, a skeptic of the Resurrection, can be quite satisfied with a statement like "the Resurrection is the best explanation of the salient facts" - a statement which is very difficult to refute, I think. Bayesian insights allow me to maintain my skepticism without undertaking hopeless endeavors, for example defending or asserting statements like "the Bible does not constitute any evidence for the Resurrection." In arguments over the Resurrection, we cannot eliminate entirely our differing private intuitions. But we can at least see what is required of those intuitions and reduce their impact when possible.

And I love this stuff for its own sake. I'm soggy like that.

Suggestions for the future: separate the witness of James the Just from that of the other apostles, subsume the testimony of the women within that of the disciples generally, and largely omit any discussion of Paul's conversion as itself evidential in favor of other details. Paul is doubtlessly important, but his importance is in his teaching and his early date. And keep it general, yo.

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