Welcome to Part II of my review of Richard Carrier’s book, *Provi**n**g History: Bayes’s Theorem and the Quest for th**e H**istorical **Jesus*.

In **chapter 2** the author provides twelve axioms (pp. 20-37) and twelve rules (pp. 37-39) of the historical method. Nothing terribly controversial about these except for, as the author himself admitted, the second part of the first rule which states that one must *“Obey… Bayes’s Theorem”*.

I will quote the second rule because not only is it a very sound piece of advice to follow, it also represents what I think is a deficiency in this book.

Rule 2: Develop wide expertise in the period, topics, languages, and materials that you intend to blaze any trails in,

or elsebase all your assumption in these areas on theestablished(and properly cited) findings of those who have. (37)

I enjoy studying early Christianity. It may seem like a simple field of research to the lay person, but in reality it is complex and requires a multi-disciplinary approach. You have to deal with literary and non-literary sources: the former necessitating specialists in philology, palaeography, papyrology, and codicology; the latter covering such disciplines as epigraphy, archaeology, and numismatics. If one desires to study Christian origins then one has to study many diverse areas, from the Dead Sea Scrolls to the Nag Hammadi library (and, of course, the relevant languages: Hebrew, Aramaic, Greek, Coptic). When it comes to historical Jesus studies, one has to deal with composite texts and traditions. Does the author, Richard Carrier, demonstrate that he is knowledgeable in this area? We will see in Part III of this review. But first a quick overview of chapter 3.

**Chapter 3** contains an introduction to Bayes’s Theorem. It is quite an informative chapter and I think the author did a pretty good job of dumbing it down for the mathematically challenged (such as myself). Of course, the author could be making horrendous mistakes in his application of Bayes’s Theorem, but since I am mathematically naïve I would not be cognizant of the fact.

In regards to the results obtained from using Bayes’s Theorem, Carrier states that we know they *“are always necessarily true –if its premises are true”*. What he means by ‘premises’ is *“the probabilities we enter into the equation”* (45). Yet as the author states, quantifying the relevant data so as to be able to input it into Bayes’s Theorem is a *subjective* endeavor, though he argues it is not an *arbitrary *one. He also says that *“you must have *reasons* for your subjective estimates”* and that *“if you do have sufficient reasons, you need to ask if those reasons will be accepted by other reasonable people”*. If they are, this *“would then actually make them objective, since by definition objective reasons will be accessible and verifiable to all reasonable observers, who will thus all come to the same subjective estimate” *(82).

Carrier seems to have high hopes concerning the ability of people to reach an agreement regarding the “subjective estimates” we should be plugging into Bayes’s Theorem. Color me a pessimist, but I am skeptical that such an agreement could be reached. As I noted in Part I of this review, it is silly to think that scholars with various ideological viewpoints would arrive at the same results by using the criteria of authenticity. The same holds for Carrier’s method of Bayesian reasoning. The different ideological stances of the people applying Bayes’s Theorem is going to generate disagreement on how to quantify all the relevant data.

Additionally, I’m curious as to how how he himself is going to quantify all the data appropriately? How is he going to handle the composite texts and traditions? Will he be able to adequately separate the primary traditions from the secondary? How is he going to deal with the multitude of issues (e.g. matters of provenance, chronology, linguistics, etc) related to the Gospels, the Pauline epistles, and other Jesus traditions? How is he going to handle alternative positions on an issue? Will he simply accept the consensus and ignore any dissenting views? How is he going to work in the fact that he is not competent when it comes to Second Temple Judaism? Will it give his “subjective estimates” a large enough margin of error to make the results meaningless? I guess we will just have to wait until the second volume is released. Though from what I saw in this volume, I am not going to set my hopes up too high.

Is Bayes’s Theorem a practical and effective tool to use in historical studies or does it just provide only a veneer of rigor and logic? This is a question perhaps best left to the mathematically literate of us. I have found one review of *Proving History* from someone who seems relatively clued in on mathematics (I would also encourage the interested reader to read Carrier’s response to that review, as well as the great comment discussion that ensued). That same blogger also makes further posts on the subject here and here (the latter link is particularly interesting in my opinion). If anyone knows of other reviews which focus on the Bayesian reasoning of *Proving of History* (whether they support Carrier’s thesis or not) then drop a comment and let me know!

I will finish this part of the review with a quote from Ian’s blog post:

So, what can we learn?

Well, for one, the inputs to Bayes’s Theorem matter. Particularly small inputs. When we’re dealing with rare evidence for rare events, then small errors in the inputs can end up giving a huge range of outputs, enough of a range that there is no usable information to be had.

And those errors come from many sources, and are difficult to quantify. It is tempting to think of errors only in terms of the data acquisition error, and to ignore errors of choice and errors of reference class.

These issues combine to make it very difficult to make any sensible conclusions from Bayes’s Theorem in areas where probabilities are small, data is low quality, possible reference classes abound, and statements are vague. In areas like history, for example.

Stay tuned for Part III of this review.

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Tim McGrew would be the main one to talk to in this area and he’s exposed Carrier on Bayes Theorem a number of times.