Tag Archives: qualitative probability

Why Richard Carrier probably won’t win over the guild, part 3

NYT Office scene

The guild knows the beat it covers.

This post concludes the series on the frosty reception of Dr. Richard Carrier’s book On the Historicity of Jesus among biblical studies academics, “the guild.” The series is not a book review of On the Historicity, but rather a sketch of a different Bayesian-style investigation parallel to Carrier’s.

Previous posts (link and link) have refined Carrier’s hypothesis specifications, considered alternatives to his permissible but unappealing choice of an initial belief state, and checked his claim to have weighted evidence systematically to disfavor his own preferred hypothesis. This post looks at some reservations about Carrier’s interpretations of ancient texts. Finally, a brief conventional Bayesian sensitivity analysis of his results sheds some light on the potential to open up the guild to new foundational ideas.

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Why Richard Carrier probably won’t win over the guild, part 2

Chaplin in Modern Times

Bayes isn’t as mechanical as some seem to think.

How confident should a reasonable person be that Jesus was a real person who actually lived? Academic biblical scholars, “the guild,” display little doubt. Dr. Richard Carrier urges a skeptical view in his book, On the Historicity of Jesus.

The first post in this series (link) specified two alternative hypotheses about Christian origins based on Carrier’s work. The next step in a Bayesian-style analysis is to compare the plausibility of the contending hypotheses based on general background information, before examining how more specific evidence about Jesus’ historical or mythical status might change the relative plausibilities.

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Why Richard Carrier probably won’t win over the guild, part 1

Workers lunch on girder

The guild sticks together and never looks down

Was Jesus a real person who actually lived, or is he instead an ancient fictional or mythological character?

Dr. Richard Carrier votes fictional or mythological. Carrier earned a Ph.D in ancient history from Columbia in 2008. Since 2014, his book, On the Historicity of Jesus: Why We Might Have Reason to Doubt has enjoyed popular success. However, the book was published by a university press (Sheffield Phoenix) specializing in biblical studies. The book was addressed to academics in that field, “the guild” as they style themselves.

Over the years, the Uncertaintist has covered some of the tense interaction between Dr. Carrier and members of the guild (link). We now await his follow-up volume, Jesus from Outer Space: What the Earliest Christians Really Believed about Christ, due out in September. As is obvious from the flippant title, the new book won’t be addressed to the academy. That’s not because the scholarly battle has been won: all but a few guild researchers still premise their work on a Jesus who really lived.

Is that because five or six years is too soon to expect to see widespread change in dominant attitudes? Maybe, but Carrier acknowledges that much of his main thesis resembles that of Earl Doherty, whose writings have been available since the 1990’s (link).

What most clearly distinguished On the Historicity from other “mythical Jesus” works was to frame its argument using Bayesian methods, introduced by Laplace in 1814. Carrier assessed specific probability numbers and ratios to express the weight of evidence and how confidently his conclusions should be held. That idea hasn’t swept the guild by storm, either.

In this short series, the Uncertaintist will look at the historicity question within the framework of a typical “Bayesian” analysis, but adapt the method to the subject matter and forget about numbers. The findings of the series can be summarized by reference to the subtitles of the two Carrier books mentioned. That we might have reason to doubt the existence of a historical Jesus can probably be supported. To convince many others that any specific mythical Jesus hypothesis is what the earliest Christians really believed about Christ probably remains out of reach for now.

This series is not a review of On the Historicity. Bushels of those are already on the web. Here, the book’s premises and outlook will be a point of departure for continuing work, now that Dr Carrier himself seems to have left us for, well, outer space.

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Brothers II: Like Jesus

George Polya

The previous installment (link) concluded that Paul’s accepted use of the phrase the brother(s) of the Lord ought not to dispel all uncertainty about the historical existence of Jesus. However, so long as it is possible that the phrase was genuinely Paul’s and that it referred to a relationship among two or more living people, then what scholarship receives as Paul’s writing, if it bears at all, counts in support of a historical Jesus and against hypotheses where he is entirely fictional or mythological.

How strong should that bearing reasonably be? This second post about these brothers is informed by “Bayesian reasoning,” but here fielded without numbers, in a style which incorporates the ideas of George Polya about qualitative plausible thinking and assessment of evidence.

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Historians and probability

Dice players

Dice players (detail, Georges de La Tour, 17th C.)

Bayesian probability theory is a formal method of reasoning about evidence. Its probabilities are typically subjective and personal measures. They represent either a real person’s felt confidence, or a hypothetical person’s theoretically justified confidence. Please do not be put off by the word subjective. Justified confidence is the foundation of prudent belief, action and behavior.

Richard Carrier is a serious independent scholar and internet celebrity who earned his doctorate in ancient history from Columbia University. He uses Bayesian methods to study history, especially the question of whether Jesus was a real historical person. Carrier professes serene assurance about the objectivity and validity of his Bayesian approach to history (link),

I don’t think I’ll convince everyone, but the only people who won’t be convinced are people who are irrationally, dogmatically opposed to what I’m arguing.

This post discusses how well Bayesian methods can resolve historical controversies, in the sense of achieving consensus founded on objective analysis of evidence. Within a community of Bayesians, objectivity and near-unanimity aren’t completely out of reach, but they tend to be elusive except when most people would be convinced whether or not they appeal to Bayes.

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De Finetti’s conjecture: First broken, then fixed; but nobody noticed, Part 2

In the first part, we left Bruno de Finetti in 1949 as he established that for four distinct individual possibilities (like which team will win a championship), any usual ordering of “tickets” that was “quasi-additive” was also “probabilistic.” He conjectured that this would be true for any finite number of quasi-additively ordered propositions, and invited the community to help prove him right or wrong.

One who accepted de Finetti’s invitation was Leonard Savage, who later developed his own landmark axiomatization of subjective probability. Savage gave the obscure 1949 paper to Charles Kraft, John Pratt and Abraham Seidenberg. They showed in 1959 that de Finetti’s conjecture was wrong if there are five or more basic outcomes.

That’s the “broken” part of the story. De Finetti’s conjecture, scribbled in haste to rebut his friend George Polya, is false. Many people scrambled to fix it. The first were Kraft, Pratt and Seidenberg themselves in 1959. A famous second time was five years later, by Dana Scott. Oddly, neither solution was satisfactory to its authors. Odder still was that De Finetti himself may have come within a whisker of repairing it back at the beginning in 1949.  Continue reading

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