Posted: Jan 25, 2012 3:38 pm
by proudfootz
logical bob wrote:
proudfootz wrote:Again, you failed to quote the introductory paragraph... Here Carrier is simply showing how application of Bayes theorem will help would-be historians from making the common mistake of failing to take into account competing theories. Again Carrier is not claiming he is 'working' the Bayes Theorem in this example.

Do you think historians are unaware of the possibility of alternative hypotheses until they see Bayes' Theorem, when they go "God, how could I have been so stupid?" Considering competing theories is just common sense, not an application of Bayes' Theorem.

Yes, probably Bayes Theorem is just a way of describing common sense. I don't understand why that should be controversial.

In discussing the 'Brother of the Lord' phrase I've often seen posters ignore the possibility of its being a title in favor of the blood kinship hypothesis without qualification. How could they be so stupid?

In the paragraph I didn't quote Carrier begins "Bayes’ Theorem will force you to examine the likelihood of the evidence on competing theories" and then says "for example..." It seems to me he is very much claiming to be working the Theorem. You're dead right to say that he actually isn't working it. How does he examine the likelihood of the competing theory? He announces that the use of Brother of the Lord as a title is "just as likely." Rigourous, huh?

You seem to be missing the point. Maybe in your rush to quote mine Carrier you forgot that this is an argument and thus needs to be followed logically:

3. Bayes’ Theorem will force you to examine the likelihood of the evidence on
competing theories, rather than only one — in other words, forcing you to consider
what the evidence should look like if your theory happens to be false (What evidence can
you then expect there to be? How would the evidence in fact be different?).
common logical errors are thus avoided. You may realize the evidence is just as likely on
some alternative theory, or that the likelihood in either case is not sufficiently different to
justify a secure conclusion.

For example, Paul refers to James the Pillar as the Brother of the Lord, and to the Brothers of the Lord as a general category of authority besides the Apostles. It is assumed this confirms the historicity of Jesus.

So here's hypothesis A: Brother of the Lord (BotL) is a blood kinship term.

Now Carrier invites us to consider an alternative hypothesis as Bayes seems to require:

But which is more likely, that a historical (hence biological) brother of Jesus would be called the Brother of the Lord, or that he would be called the Brother of Jesus? In contrast, if we theorize that ‘Brother of the Lord’ is a rank in the Church, not a biological status, then the probability that we would hear of authorities being called by that title is just as high, and therefore that Paul mentions this title is not by itself sufficient evidence to decide between the two competing theories of how that title came about.

So in the hypothetical situation Carrier sets out, with no evidence to chose between the two, we cannot say either is 'more likely' than the other and they are for all practical purposes equally likely.

But the argument does not end there, as you may not have noticed:

Estimates of prior probability might then decide the matter, but one then must undertake a total theory of the evidence (extending beyond just this one issue), since there is no direct evidence here as to what was normal (since there is no precedent for calling anyone “Brother of the Lord” as a biological category, and only slim or inexact precedent for constructing such a title as a rank within a religious order).

Thus Carrier points out that the guesses about what is 'more likely' must be tempered by consideration of competing hypotheses and this process may expose why the original reading cannot be regarded as 'more likely' after all.

What he's doing is trying to give a mathematically illiterate audience the impression that the standard arguments he uses elsewhere are the product of a mathematical approach.

So long as you want to argue that 'probable' and 'likely' as used by historians are terms that are empty of any notion of 'how likely' or 'how probable' it becomes difficult to tell the level of confidence we should place in such pronouncements.

Your inspired effort at 'mind reading' Carrier's intention is a credit to all rational skeptics everywhere!

It's pretty much like an advert for skin cream being fronted by someone with a white coat and glasses.

Except in this case it's a historian discussing historical method.

A completely different thing.