Posted: Feb 01, 2012 11:23 pm
by Mus Ponticus
logical bob wrote:Sounds to me as if Carrier wants to have his cake and eat it. On the one hand he wants us to think that this is a valuable tool that will work better that the alternatives and on the other he wants to say that this is what we already do anyway. If criticism of your new tool is really criticism of all human reasoning then you haven't added anything new.
You're not being very logical, bob. Carrier is merely saying that this specific objection is as valid against Bayes' (I will from now on abbreviate it as BS :P ), as it is against normal reasoning.

E.g. next time Byron says: "It's most probable that the meaning of 'brother of the lord' is biological.", the same objection would be: "Probable? That's a mathematical term. Show me the math or stop using that term! Are you just pulling 'most probable' out of thin air?"

Byron wrote:This isn't an interrogation. I answer exactly if and when I want to. You didn't offer any examples before, so I had no interest in answering.
You made a specific claim regarding Carrier's case, and I asked you to back that claim up. I don't know why I should give examples when asking you to back up your claims.

Byron wrote:I agree that I don't understand what he's saying, but that's because his position is so muddled I doubt the Bletchley Park folks could fully decode it.
Blame the messenger ;)

In the pdf of his lecture, one section's titled, "Advancing to Increasingly Objective Estimates," and elaborates, "The fact that we can improve the certainty of our conclusions by improving the certainty of our estimates of likelihood and unlikelihood is precisely what historians need to learn from Bayes' Theorem."

So Carrier thinks that historians can use math to infuse objectivity into assessments of historical probability. The problem comes in his failure to demonstrate how the formula transfers to the evidence.
I'm not sure what you think he's saying there. Look at this quote from that same section:

In other words, the question must be asked, “How do you get those values? Do you just pull them out of your ass?” In a sense, yes, but in a more important sense, no.

You aren’t just blindly making up numbers. You have some reason for preferring a low number to a high one, for example (or a very low one to one that’s merely somewhat low, and so on), and the strength of that reason will be the strength of any conclusion derived from it—by the weakest link principle, i.e. any conclusion from Bayes’ Theorem will only be as strong as the weakest premise in it (i.e. the least defensible probability estimate you employ).
Byron, imagine this. If you take up a book on the HJ, would you think it absurd if the author, instead of saying "probably true", "very probably true" and "almost certainly true", used numbers instead? E.g. "70% probability of being true", "80% probability of being true" and "90% probability of being true"?