General question: I've read somewhere that there's a Bayesian approach to at least partially justifying simplicity arguments / Occam's Razor. Where can I find a good accessible explanation of this?

Specifically: Say you're presented with a body of evidence and you come up with two sets of explanations for that evidence. Explanation Set A consists of one or two elegant principles that explain the entire body of evidence nicely. Explanation Set B consists of hundreds of separate explanations, each one of which only explains a small part of the evidence. Assuming your priors for each individual explanation is about equal, is there a Bayesian explanation for our intuition that we should bet on Explanation Set A?

What about if your prior for each individual explanation in Set B is higher than the priors for the explanations in Set A?

Example:

Say you're discussing Bible Criticism with a religious friend who believes in the traditional notion of complete Mosaic authorship but who is at least somewhat open to alternatives. To your friend, the priors for Mosaic authorship are much higher than the priors for a documentary or fragmentary hypothesis. (If you want numbers, say that your friend's priors are .95 in favor of Mosaic authorship.)

Now you present the arguments, many of which (if I understand them correctly) boil down to simplicity arguments:

• Mosaic authorship requires either a huge number of tortured explanations for individual verses, or it requires saying "we don't know" or "God kept it secret for some reason". Documentary-type hypotheses, on the other hand, postulate a few basic principles and use them to explain virtually everything.
• Several different lines of local internal evidence often point to exactly the same conclusions. For example, an analysis of the repetitions within a story might lead us to divide up the verses between authors in a certain way, while at the same time an independent stylistic analysis leads us to virtually the same thing. So we again have a single explanation set that resolves multiple sets of difficulties, which again is simpler / more elegant than the alternative of proposing numerous individual explanations to resolve each difficulty, or just throwing up our hands and saying God keeps lots of secrets.

The question is, is your friend justified in rejecting your simplicity-based arguments based on his high priors? What about if his priors were lower, say .6 in favor of Mosaic authorship? What about if he held 50-50 priors?