My review of Richard Carrier's "On the Historicity of Jesus"

[gakuseidon]

All,

I've posted a fairly comprehensive review of Richard Carrier's book "On the Historicity of Jesus" here:
members.optusnet.com.au/gakuseidon/Carrier_OHJ_Review.html

Any comments welcomed!

Also, I'm looking for positive reviews of Carrier's "Proving History", where he describes using Bayes's Theory for questions of history. But the reviews should be by mathematicians, or at least someone with experience in using it. I've added some negative reviews into my OHJ review, since there appears to be issues around using BT for history. But I'd like to balance that by adding positive reviews. In fact, any positive review around using BT for questions of history, related to Carrier's work or not, would be good.

I know very little about BT, but I think it would be great if we could use it for history!

[unkleE]

Just a brief, inexpert comment. I have some small knowledge of statistics (I studied it for one year at Uni and obtained a Distinction) and I have played around with Bayes Theorem a little. It is true that GIGO, but I think it is also true that clarifying assumptions and putting numbers on things, as using Bayes Theorem requires, is helpful. I see no reason why it shouldn't be used in history, provided too much isn't claimed for the result. I note that Christian Philosopher Richard Swinburne (who I find difficult to read and not highly convincing, though he is generally highly respected) uses Bayes Theorem in philosophy.

That is not necessarily support for Carrier's use of statistics. He comes across as so egotistical and one-sided that I'd have little confidence in how he would use it.

Thanks for your review - I haven't read all of it (I'm not that interested in Carrier) but I appreciated your overview.

Additional (later) note:

In case anyone else has expertise on Bayes Theorem, I'd be interested in any comments on a Bayes calculation I have done. It concerns miracle healing reports, and how they change the probability that God exists. I'm not so much concerned about the conclusion (we can argue that til the cows come home) but my Bayes calculation. It is in Miracles and probability: the adventures of a maths nerd. Any comments welcome.

[ignorantianescia]

Don, you have written a few times you would like a case for historicity. How do you think Ehrman's and Casey's books fared in that sense?

From the look of it Carrier still falls prey to the Mythicist inclination to positivism: bury unproblematic test/passages under non-problems in order to reject them.

[gakuseidon]

May 23, 2015 9:11:39 GMT ignorantianescia said:

Don, you have written a few times you would like a case for historicity. How do you think Ehrman's and Casey's books fared in that sense?

I haven't read Casey's book, but I have Ehrman's "Did Jesus Exist?" I thought Ehrman did a reasonable job on criticizing the mythicists, but I wasn't impressed with his case for a historical Jesus. It seemed to rely on the old assumptions that are being questioned in the first place. E.g. the Gospels are some kind of ancient biographies, Paul wrote his letters around the 50s CE. I think the assumptions are reasonable, but since many of them are being questioned by mythicists in the first place, it does no good to use them without showing their validity.

I'd like to see something laid out along the lines of Carrier's OHJ, showing the background information, the primary sources, etc, and building a case basically from scratch. I don't think that has been done yet. (BTW I noted in my review that Carrier still relies on some assumptions for his case, like there was actually a Paul writing around the 50s CE.)

[gakuseidon]

May 22, 2015 21:55:14 GMT unkleE said:

Just a brief, inexpert comment. I have some small knowledge of statistics (I studied it for one year at Uni and obtained a Distinction) and I have played around with Bayes Theorem a little. It is true that GIGO, but I think it is also true that clarifying assumptions and putting numbers on things, as using Bayes Theorem requires, is helpful. I see no reason why it shouldn't be used in history, provided too much isn't claimed for the result. I note that Christian Philosopher Richard Swinburne (who I find difficult to read and not highly convincing, though he is generally highly respected) uses Bayes Theorem in philosophy.

Yes, I agree that it might be helpful in history, but I'd like to understand its limitations, and how they apply to questions of history.

[unkleE]

Well I don't see history as any different in principle than any other area of knowledge. Bayes Theorem simply says that if some new information is more likely to have occurred if a certain proposition is true than if that proposition is false, then even if it doesn't offer any "proof" of the proposition, it still increases the probability that the proposition is true. That makes sense, but people don't always act as if it's so. So if we can formally define propositions and can reasonably assess whether some new evidence would be more likely if that proposition is true or false, we can draw the conclusion, even if any numbers we put on it are only notional.

Is it possible for you to post one of Carrier's uses of the Theorem, or would it be too long?

[gakuseidon]

May 23, 2015 13:35:05 GMT unkleE said:

Is it possible for you to post one of Carrier's uses of the Theorem, or would it be too long?

I put some of the odds that Carrier produces in my review, but the odds are based on analysis that Carrier does beforehand. It would be too long to reproduce the analysis I'm afraid. But there is no mathematical rigor around his numbers. It's mostly "we wouldn't see this if there was a 'minimal historical Jesus', so therefore the odds are 4-to-5 in favour of 'minimal mythicism'. In a way it is an extended argument by incredulity in many cases; still, I do think it is a start in trying to establish a foundation in the evidence to be used one way or the other.

[unkleE]

I am interested because my experience of using Bayes Theorem suggests it exaggerates the conclusions from what we would naturally think. There is a book called "The Probability of God" by Stephen Unwin (who uses Bayes in his work in risk assessment). He looks at 6 "facts" and applies Bayes to them to calculate the probability that God exists. The answer, surprisingly, is not 42 but 0.7. It's a simple and simplistic approach, but the book actually contains some useful insights despite that.

Anyway, I thought it looked like fun, so I decided to enlarge the calculation a bit and give more options on the numbers than he did. It works (see The Probability of God test). But here's the difficulty. Using what I thought was a reasonable range of options for the probabilities in each question, I found that most calculations quickly went to one of the extremes - either close to zero or close to one. I reduced the range of possible probabilities, and it was a little better, but I still think getting to a probability of God's existence of 0.0001 or 0.9999 is not representative of what most people really think (except when they're in argumentative mode).

So while I think Bayes can be useful, especially in forcing us to make our assumptions and assessments of evidence explicit, I wonder whether it is a case of unjustified assumption in, unjustified conclusion out.

[gakuseidon]

May 26, 2015 21:49:26 GMT unkleE said:

So while I think Bayes can be useful, especially in forcing us to make our assumptions and assessments of evidence explicit, I wonder whether it is a case of unjustified assumption in, unjustified conclusion out.

Bayes's Theorem (BT) is a formula so it is definitely affected by "Garbage In, Garbage Out". My question is though how do we define Garbage for BT?

Carrier uses "Best Case" and "Worst Case" odds, and for the Epistles, he calculates that on Best Case the odds are about 3:1 in favour of historicity and Worst Case is 1:16 (from memory) against historicity. That's a wide range, about 4500%!

In my review I equate that to the example "Will it rain on Suzie's wedding day?", with the Best Case being "No" and the Worst Case being "Tornado!" The figures produced may reflect the inputs, but a realistic answer would be "We don't know whether it will rain or not on Suzie's wedding day."

Similarly, I wonder if the wide range of results for the Epistles means we can't use the results at all. I'd like to understand the real world applications for BT, and whether there are rules or guides around what inputs to use. How much certainty do we need beforehand in order to know we can use BT? That's something Carrier is silent on, from what I've read.

[unkleE]

Perhaps you should read cosmologist Luke Barnes discuss Carrier's understanding and use of Bayes Theorem, as applied to the fine tuning of the universe - here and here. You don't need to worry about understanding the maths or the detailed cosmology, just read the general text.

Barnes is a research cosmologist working on "cosmological simulations of galaxy formation to try to make precise the connection between the fundamental parameters of cosmology – like the density of matter, the lumpiness of the early universe and the cosmological constant – and the conditions required by stars, and hence anything that requires stars." and has published on fine-tuning, so he knows a thing about fine-tuning and about mathematical modelling. He has shown in these two blog posts, and elsewhere, that Carrier knows very little about fine-tuning but talks as if he knows a lot.

Barnes has also given a talk on Bayes to an eminent group of scientists - "The goal is to take Bayesian probability theory as it is used in the physical sciences and see if it can make sense of postulating and testing a multiverse theory." So we can safely assume he knows a bit about Bayes Theorem as well. And he points out enormous gaps in Carrier's understanding of probability generally and Bayes Theorem in particular. Barnes concludes:

This is from a guy who has lectured on Bayes’ theorem (heaven help those students) and written books and articles with “Bayes’ theorem” in the title. Carrier’s faults are not slips of notation, minor technicalities or incorrect arithmetic. While presenting himself as a modern Bayesian, he is actually a finite frequentist, subscribing to an outdated, overly restrictive and practically useless interpretation of probability. He offers no defence of finite frequentism, fails to mention its tension with Bayesianism and ignores its clear failure to account for probability as it is used in cosmology (relevant to fine-tuning), scientific discovery, and history (Carrier’s own field). Carrier can’t even apply his own half-baked ideas consistently, abandoning them when convenient.

Further, when the time comes to demonstrate the use of Bayes’ theorem, Carrier bypasses it. He tries to argue that likelihoods are irrelevant to posteriors. The whole point of Bayes’ theorem is to use likelihoods (and priors) to calculate posteriors. No scientist, no statistician does probability like this, and for good reason.

None of which helps you assess Carrier's claims about the gospels and Jesus, but may make you wonder whether you need to, or at least expect the worst.

I think it is pretty clear what we should use as inputs - we start with a prior probability that a proposition is true. Then we look at some evidence and ask how probable is it that this evidence would occur (i) if our proposition is true, and (ii) if our proposition is false? Then we use Bayes Theorem to calculate a new probability that the proposition is true. The accuracy of (i) and (ii) may be low, but provided the ratio of one to the other is reasonable, we can get a reasonable answer. We can do the calc several times for different prior probabilities, to see how much the new information changes it.

The calculation is simple, but from what Barnes says, Carrier didn't define his terms, doesn't understand Bayes, used inconsistent methods and poorly justified numbers. We may expect the same thing here, perhaps, but you and I may not be able to know. I think I'd check his assumptions and definitions. If someone who knew something about Bayes did these calcs, I can't see why they wouldn't have some meaning and value, but it is doubtful if Carrier meets that simple requirement.

[ignorantianescia]

May 23, 2015 12:27:48 GMT gakuseidon said:

May 23, 2015 9:11:39 GMT ignorantianescia said:

Don, you have written a few times you would like a case for historicity. How do you think Ehrman's and Casey's books fared in that sense?

I haven't read Casey's book, but I have Ehrman's "Did Jesus Exist?" I thought Ehrman did a reasonable job on criticizing the mythicists, but I wasn't impressed with his case for a historical Jesus. It seemed to rely on the old assumptions that are being questioned in the first place. E.g. the Gospels are some kind of ancient biographies, Paul wrote his letters around the 50s CE. I think the assumptions are reasonable, but since many of them are being questioned by mythicists in the first place, it does no good to use them without showing their validity.

I'd like to see something laid out along the lines of Carrier's OHJ, showing the background information, the primary sources, etc, and building a case basically from scratch. I don't think that has been done yet. (BTW I noted in my review that Carrier still relies on some assumptions for his case, like there was actually a Paul writing around the 50s CE.)

Those aren't really assumptions though, but rather conclusions from (maybe not very forceful) inductive arguments. Reasons for dating Paul 'early' would be quotes in patristic writings, the lack of themes that would interest a later forger (theological disputes, references to the fall of Jerusalem), promoting an eschaton while some of the people who knew Jesus were still alive (this would really make little sense when all those people were dead!), the sometimes unflattering views of prominent people in the early church and Paul's familiarity with Pharisaic interpretations of Scripture.

Sure, these arguments are not about to convince devil's advocates, but that is not how the default position to historical sources is. In absence of plausible reasons to doubt a source, it should be used, though critically.

[gakuseidon]

May 27, 2015 13:02:41 GMT unkleE said:

Perhaps you should read cosmologist Luke Barnes discuss Carrier's understanding and use of Bayes Theorem, as applied to the fine tuning of the universe - here and here. You don't need to worry about understanding the maths or the detailed cosmology, just read the general text.

Barnes is a research cosmologist working on "cosmological simulations of galaxy formation to try to make precise the connection between the fundamental parameters of cosmology – like the density of matter, the lumpiness of the early universe and the cosmological constant – and the conditions required by stars, and hence anything that requires stars." and has published on fine-tuning, so he knows a thing about fine-tuning and about mathematical modelling. He has shown in these two blog posts, and elsewhere, that Carrier knows very little about fine-tuning but talks as if he knows a lot.

Barnes has also given a talk on Bayes to an eminent group of scientists - "The goal is to take Bayesian probability theory as it is used in the physical sciences and see if it can make sense of postulating and testing a multiverse theory." So we can safely assume he knows a bit about Bayes Theorem as well. And he points out enormous gaps in Carrier's understanding of probability generally and Bayes Theorem in particular. Barnes concludes:

This is from a guy who has lectured on Bayes’ theorem (heaven help those students) and written books and articles with “Bayes’ theorem” in the title. Carrier’s faults are not slips of notation, minor technicalities or incorrect arithmetic. While presenting himself as a modern Bayesian, he is actually a finite frequentist, subscribing to an outdated, overly restrictive and practically useless interpretation of probability. He offers no defence of finite frequentism, fails to mention its tension with Bayesianism and ignores its clear failure to account for probability as it is used in cosmology (relevant to fine-tuning), scientific discovery, and history (Carrier’s own field). Carrier can’t even apply his own half-baked ideas consistently, abandoning them when convenient.

<snipped>

That's excellent! Thanks for the link, unklee. I've added it to my review.

I'd still like to add a positive review of Carrier's use of BT from someone who knows BT into my review for balance, but there just doesn't appear to be one out there.

[sandwiches]

For those who are interested there is an opportunity to bid for priceless literary investments:

freethoughtblogs.com/carrier/archives/8118#more-8118

www.ebay.com/itm/252034300520?clk_rvr_id=875187025623&afsrc=1&rmvSB=true

[unkleE]

Jul 28, 2015 21:04:51 GMT sandwiches said:

For those who are interested there is an opportunity to bid for priceless literary investments:

freethoughtblogs.com/carrier/archives/8118#more-8118

www.ebay.com/itm/252034300520?clk_rvr_id=875187025623&afsrc=1&rmvSB=true

I think we should all chip in and buy a set for Tim's birthday!!

[wraggy]

Jul 29, 2015 1:51:37 GMT unkleE said:

Jul 28, 2015 21:04:51 GMT sandwiches said:

For those who are interested there is an opportunity to bid for priceless literary investments:

freethoughtblogs.com/carrier/archives/8118#more-8118

www.ebay.com/itm/252034300520?clk_rvr_id=875187025623&afsrc=1&rmvSB=true

I think we should all chip in and buy a set for Tim's birthday!!

May he worship at the altar and give praise to the genius of Richard.