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

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

Post by timhendrix » Wed Mar 23, 2016 9:44 am

I have uploaded my review of Richard Carrier's book "On the historicity of Jesus". My review focuses on Carriers application of Bayes theorem, so don't expect to see it proven whether Jesus existed or not, but rather if the argument in OHJ is sound. The full review is here:
https://www.scribd.com/doc/305750452/Ri ... y-of-Jesus

I have elsewhere written about "Proving history" which may be relevant as OHJ and PH share difficulties:
https://www.scribd.com/doc/271358647/Ri ... ory-Review
(see also the related discussion on Vridar:)
http://vridar.org/2015/07/21/miscellane ... s-updates/

My conclusion is I do not think the argument in OHJ is sound. To summarize the conclusion:
  • Rather than considering binary propositions (historical vs not historical), Dr. Carrier considers compound propositions (the different scenarios for mythicism and historicity) which makes the evidence far easier to explain on mythicism.
  • Information which would otherwise be considered evidence (the Rank-Raglan information and who knows what else which according to Dr. Carrier makes the compound propositions likely) is moved into the background information to argue the compound proposition is very likely true. These moves may be formally true, however they require us to estimate much, much more complicated probabilities however—
  • Dr. Carrier makes a simplistic and false frequentistic argument to compute the probability of his (non-binary!) compound propositions as the number of historical figures in the Rank-Raglan class vs. the total number of elements in the Rank-Raglan class. This is erroneous as it ignores information specific to Jesus or Dr. Carriers specific hypothesis.
  • Since the prior probability do not reflect the compound proposition nor that information has been moved from the evidence to the background information the argument is false
I would be very thankful to have errors or other difficulties in the argument pointed out. Comments can also be send to my email timhendrix(at)gmx.com (I can't respond to messages here since I am a new member).

Giuseppe
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Re: My review of Richard Carrier's "On the Historicity of Je

Post by Giuseppe » Wed Mar 23, 2016 11:00 am

forgive me if I have read quickly (and not closely) your review, but when you write:
the use of a compound propositions (the theory for mythicism) will likely bias the computation in favor of mythicism as it quite plainly makes many pieces of evidence far more easily explainable than any generic theory for mythicism.
I do not know why this should be a manifestation of 'bias'. I've always thought that it is right to identify the mythicist scenario that makes most sense (compared to other mythicist scenarios), and compare that with the best historicist scenario.

Do you mean that the only problem of the use of compound propositions is the Carrier's use of priors? if your answer is yes, I may agree.

But if your answer is no, I may disagree with the equation : too specific = too bias.

I think it's not a ''specific'' idea to think that the Jesus of Paul is a celestial figure.

Thanks in advance for your reply.

Giuseppe
Nihil enim in speciem fallacius est quam prava religio. -Liv. xxxix. 16.

timhendrix
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Re: My review of Richard Carrier's "On the Historicity of Je

Post by timhendrix » Wed Mar 23, 2016 11:19 am

Hi Giuseppe,

I mean it in the first sense. I agree we properly have to think in terms specific scenarios for pragmatic reasons*, however it requires that we can estimate the prior probability of the scenarios we consider. I am not sure I understand your point regarding Paul and the celestial Jesus. The problem is of course that we have to carefully define what our background information is as well as our "bare historicity" assumption in order to talk about what is unexpected. If for instance "bare historicity" is simply that a person existed then I do think the celestial Jesus is plausibly unexpected on the negation of historicity. For instance other non-historical characters like John Frum, Moses or Robin Hood does not have a similar "celestial" existence.

* Formally, we would have to account for all scenarios when we compute probabilities and not just the most likely but this is a side point.

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MrMacSon
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Re: My review of Richard Carrier's "On the Historicity of Je

Post by MrMacSon » Wed Mar 23, 2016 12:53 pm

timhendrix wrote: I have uploaded my review of Richard Carrier's book "On the historicity of Jesus". My review focuses on Carriers application of Bayes theorem ... if the argument in OHJ is sound. The full review is here:
To summarize the conclusion:
  • Rather than considering binary propositions (historical vs not historical), Dr. Carrier considers compound propositions (the different scenarios for mythicism and historicity) which makes the evidence far easier to explain on mythicism.
  • Information which would otherwise be considered evidence (the Rank-Raglan information and who knows what else which according to Dr. Carrier makes the compound propositions likely) is moved into the background information to argue the compound proposition is very likely true. These moves may be formally true, however they require us to estimate much, much more complicated probabilities however—
  • Dr. Carrier makes a simplistic and false frequentistic argument to compute the probability of his (non-binary!) compound propositions as the number of historical figures in the Rank-Raglan class vs. the total number of elements in the Rank-Raglan class. This is erroneous as it ignores information specific to Jesus or Dr. Carriers specific hypothesis.
  • Since the prior probability do not reflect the compound proposition nor that information has been moved from the evidence to the background information the argument is false
Giuseppe wrote: .. you write:
the use of a compound propositions (the theory for mythicism) will likely bias the computation in favor of mythicism as it quite plainly makes many pieces of evidence far more easily explainable than any generic theory for mythicism.
You make repeated references to 'compound propositions' in your blog post, and it's also mentioned in that quote posted by Giuseppe, yet isn't Bayesian probabilities essentially about the degree to which propositions imply other propositions?

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Re: My review of Richard Carrier's "On the Historicity of Je

Post by timhendrix » Wed Mar 23, 2016 1:20 pm

MrMacSon: "compound proposition" is simply my way of saying that the proposition is the conjunction of several simpler propositions, it's just a qualitative term like "heavy". There is nothing wrong with the use of compound propositions, however if one choose to do so one has to keep in mind that the probability of a compound proposition is less than the probability of any of it's constituting parts and is as a rule more difficult to estimate.
Regarding bias, I am not sure I understand your question, however suppose we consider the probability of

F : NASA has never send a man to the moon

Clearly there is a lot of evidence which is much more difficult to explain on F than on the negation of F (videos, testimony, samples, etc.). However if we consider the compound proposition:

F' : NASA has never send a man to the moon AND the Apollo moon landings were faked as part of a giant conspiracy

Obviously F' would quite easily explain most of the evidence since it is build into F'. That's simply what I am talking about when I mention bias and compound propositions. From a formal point of view, one can naturally obtain consistent results by using F' provided one can estimate the prior probability of F' accurately. My point in the review is that Carrier does not do this.

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MrMacSon
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Re: My review of Richard Carrier's "On the Historicity of Je

Post by MrMacSon » Wed Mar 23, 2016 1:33 pm

timhendrix wrote: MrMacSon: "compound proposition" is simply my way of saying that the proposition is the conjunction of several simpler propositions, it's just a qualitative term like "heavy". There is nothing wrong with the use of compound propositions, however if one choose to do so one has to keep in mind that the probability of a compound proposition is less than the probability of any of it's constituting parts and is as a rule more difficult to estimate.
It would seem to the degree to which one uses simple propositions or use compound propositions. I imagine compound propositions can be broken down to a series of simple propositions and probably should be for the sake of Bayes calculations (in light of the notion that Bayesian probabilities is essentially about the degree to which propositions imply other propositions)
timhendrix wrote: Regarding bias, I am not sure I understand your question ...
I didn't make mention of bias (or F). I asked "isn't Bayesian probabilities essentially about the degree to which propositions imply other propositions?"

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Re: My review of Richard Carrier's "On the Historicity of Je

Post by timhendrix » Wed Mar 23, 2016 2:18 pm

MrMacSon: Oh. Yes that's essentially it. Bayesian probabilities is a consistency requirement on the assignment of probabilities.

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MrMacSon
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Re: My review of Richard Carrier's "On the Historicity of Je

Post by MrMacSon » Wed Mar 23, 2016 4:41 pm

timhendrix wrote: MrMacSon: "compound proposition" is simply my way of saying that the proposition is the conjunction of several simpler propositions, it's just a qualitative term
I get that now I've looked at this - http://plato.stanford.edu/entries/bayes-theorem/#1

andrewcriddle
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Re: My review of Richard Carrier's "On the Historicity of Je

Post by andrewcriddle » Thu Mar 24, 2016 3:31 am

I found it an interesting article

One minor error. You say
For instance in 1st Corinthians Jesus is said to have been killed by the Jews; Dr. Carrier believes this to be an interpolation and Paul was
actually referring to a heavenly crucifixion by Demons
I think this confuses 1 Thessalonians
2:14 For you, brothers and sisters, became imitators of God’s churches in Judea, which are in Christ Jesus: You suffered from your own people the same things those churches suffered from the Jews 15 who killed the Lord Jesus and the prophets and also drove us out. They displease God and are hostile to everyone 16 in their effort to keep us from speaking to the Gentiles so that they may be saved. In this way they always heap up their sins to the limit. The wrath of God has come upon them at last
which Dr Carrier regards as an interpolation and I Corinthians
None of the rulers of this age understood it, for if they had, they would not have crucified the Lord of glory.
which Dr Carrier interprets as referring to a heavenly crucifixion.

Andrew Criddle

Giuseppe
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Re: My review of Richard Carrier's "On the Historicity of Je

Post by Giuseppe » Thu Mar 24, 2016 7:54 am

Hi Tim,

If am not wrong, I remember that somewhere in Proving History Dr. Carrier thinks that it's possible to apply his (~)Bayesian method on the topic without by need to compute the priors at all (i.e., assuming fifty-fifty as priors pro and against historicity).

Do you agree?

If your answes is yes (therefore assuming that the problem about the priors has at least a solution), what would be your conclusion about resulting probabilities under that case?

Thanks,
Giuseppe
Nihil enim in speciem fallacius est quam prava religio. -Liv. xxxix. 16.

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