youngalexander

Richard Carrier: BAYES’S THEOREM and the Quest for the HISTORICAL JESUS (or via: amazon.co.uk)
(Why not Bayes’ Theorem? Still that is the way it is!)

CHAPTER 1: THE PROBLEM
RC wastes no time before describing the moribund state of current historical Jesus studies, a circumstance quite familiar to most members of this board. He cites various analyses which conclude that the recent ‘method of criteria’ fail to produce a consensus. “The entire field of Jesus studies has been left without any valid method”. The reason being either invalid criteria, invalid application or a ‘Threshold Problem’ involving the number & weight of criteria and their significance.

THE CONSEQUENCE of this FAILURE is the current multiplicity of plausible Jesus types which abound in the literature. RC cites Jesus the Jewish Cynic Sage, Rabbinical Holy Man (or Devoted Pharisee, or Heretical Essene, etc.), Political Revolutionary, Zealot Activist, Apocalyptic Prophet. Messianic Pretender, as well as many other more exotic contenders.
“When everyone picks up the same method, applies it to the same facts, and gets a different result, we can be certain that that method is invalid and should be abandoned.”

THE SOLUTION is the application of Bayes’s Theorem (BT).


CHAPTER 2: THE BASICS
In WHY HISTORY REQUIRES EXPERTISE, RC describes four stages of historic analysis. Textual, literary, source and only last, is historical analysis proper. He then sets down a set of 12 core epistemological assumptions. THE AXIOMS OF HISTORICAL METHOD and discusses them in turn with some illustrative examples mostly derived from ancient times. These are then followed by 12 RULES OF HISTORICAL METHOD which are simply stated without individual comment. The number twelve seems somewhat biblical, although given RC’s proclivities I severely doubt it. Must be coincidence, or irony, whatever!


CHAPTER 3: INTRODUCING BAYES’S THEOREM
WHEN DID THE SUN GO OUT? is an interesting example from the Gospels that RC analyses both historically and scientifically and then contrasts with a similar hyperthetical event from 1983, for the purpose of extolling the different evidentiary probabilities involved. He also introduces the question of lack of evidence or silence from expected sources. Finally concluding that this is “a slam-dunk Argument from Silence” with respect to the nonhistoricity of the Gospel account.

FROM SCIENCE TO HISTORY begins the discussion of BT: “all valid historical reasoning is described by Bayes’s Theorem”. A gentle nonmathmatical exposition canvassing a variety of historical scientific disciplines to purely historical. WHAT IS BAYES’S THEOREM applies more lubricant until at last pg.50 exposes the reader to “this rather daunting equation:”, which I shall spare you. There follows immediately a translation “into English” and several pages of explanation where prior probability and what RC refers to as consequent probability are discussed.

A BAYESIAN ANALYSIS OF THE DISAPPEARING SUN re-examines the Gospel and 1983 (now assumed fully observed) examples by employing the ‘daunting equation’ in thorough detail with the unsurprising result that the simple arithmetic yields Gospel event 0.01%, 1983 99.9%. As an introduction to BT methodology this is a painless, interesting and instructive exercise and should cause no problem for anyone with a genuine interest in the subject.

WHY BAYES’S THEOREM? further discusses the advantages of employing this methodology and then answers some initial reservations which RC has clearly been exposed to over the years.
But what has math to do with history?
But math is hard.
But history isn’t that precise.
RC’s reply to these legitimate concerns are fulsome and reasonable. Then he is a historian. I am not and would be more inclined to shout – get with the program, ‘Ship up or Shape out!’.

MECHANICS OF BAYES’S THEOREM is “the most math-challenging section of the book”. In truth there is very little more in the way of equations, and even then merely a mild extension of the forgoing. Rather there follows an extensive exposition of usage. That is mechanics of prior probability, mechanics of consequent probability, a Venn diagram, consequent probability and historical contingency, the role of conditional probability, the problem of subjective priors, arguing a fortiori, mediating disagreement and a canon of probabilities.


CHAPTER 4: BAYESIAN ANALYSIS OF HISTORICAL METHODS
As specified RC proceeds to use BT to analyse;
The Argument From Evidence (AFE)
The Argument to the Best Explanation (ABE)
The Hypothetico-Deductive Method (HDM)
Then is given a Formal Proof of Universal Applicability which is quite brief, except for the caveats and explanitary discussion, but eventually all is well. Next follows,
Bayesian Analysis of the ‘Smell Test’, and the most fun of all,
Bayesian Analysis of the Argument from Silence.


CHAPTER 5: BAYESIAN ANALYSIS OF HISTORICITY CRITERIA
RC identifies “at least eighteen distinctive criteria”, such as Dissimilarity, Embarrassment, Coherence, etc.
Embarrassment receives the most extensive treatment and falls under the BT axe for a variety of reasons. There follows a SPECIFIC INADEQUACY OF THE CRITERION OF EMBARRASSMENT involving a detailed examination of; Jesus’ crucifixion by Romans, Jesus birth in Nazareth, John’s baptism of Jesus, Jesus’ ignorance of the future, Did Jesus know he was the Son of Man?, Jesus betrayal by Judas Iscariot, And so on …
The remainder of the criteria fall with increasing rapidity, as do some OTHER CRITERIA.

However, a BAYESIAN ANALYSIS OF EMULATION CRITERIA survive (with modification) and prove most instructive when “Daniel in the lion’s den” becomes “Jesus in the empty tomb”.

Finally in BAYESIAN DEMONSTRATIONS OF AHISTORICITY “… at first glance it seems surely “Jesus existed” would win out as the most probably hypothesis on BT. In my next volume (On the Historicity of Jesus Christ) I’ll reveal that on second glance, that conclusion is not so obvious, and might even be wrong”.


CHAPTER 6: THE HARD STUFF
The final chapter addresses “deeper issues regarding the application and applicability of Bayes’s Theorem generally”. It contains some new maths but is mostly concerned with technical aspects of BT and its use in historical research.

The book is well written with a clear and logical progression of argument. The mathmatical development could hardly be more benign and there are many illustrative and entertaining examples to elucidate the details of both methodology and application. From a technical and logical perspective it very adequately covers the ground required to inderpin RC’s next volume. However, just how his colleagues in the Acadamy will assess it is beyond my ken, and remains to be seen.

outhouse

RC takes pride in playing the middle of the road.


good write up

thanks