Posted:

**Jan 25, 2012 2:07 pm**Mus Ponticus wrote:Carrier doesn't say that all valid arguments use Bayes' theorem, he's saying that you can use Bayes' theorem to describe any valid arguments.

I can see that's what he says, but I'm trying to get past his clumsy terminology to see what he means. If he thinks "any argument that violates Bayesâ€™ Theorem is invalid. All valid historical arguments are described by Bayesâ€™ Theorem" makes sense then when he says "are described by" he must mean "do not violate". Although he's trying to give the appearance of a tight logical argument in this paragraph he isn't clear on what he means by violating a theorem or describing an argument. I was paraphrasing him in the hope of making his point at least coherent.

I'd be willing to accept that an argument that used probabilities in a way contradicted by a correct application of Bayes' Theorem would be invalid. It simply does not follow from this Bayes' Theorem has any bearing on all valid arguments, for the reason I gave.

The bigger point is that history doesn't handle probabilities in a mathematical way and has never claimed to do so. A mathematical treatment of probability requires that the probabilities be expressed numerically. Who's attempting to put numbers of the chances of Brother of the Lord being a biological relationship rather than a title? Nobody. So what exactly is the role of a process that requires numbers as input?