Tim Hendrix, a mathematician, recently published an inaccurate critique of my book On the Historicity of Jesus. This is my analysis of where he went wrong. Hendrix wrote a critique of my book Proving History: Bayes’s Theorem and the Quest for the Historical Jesus a few years ago, which I addressed last year. This year’s critique is of its sequel.

Minor Issues

Hendrix’s description of OHJ says some strange things. Hendrix says that chapter 1 “Surveys what constitutes relevant evidence. Dr. Carrier concludes the relevant evidence can be divided into four categories: (i) extra biblical evidence, (ii) acts, (iii) the gospels and (iiii) the epistles.” That’s not chapter 1. That describes chapter 7. Chapter 1 does outline the contents of the book (in a single page), which lists the evidence breakdown, but it does not “survey” what evidence counts or why. Most of chapter 1 is about the context of the debate, not the evidence deciding it. Hendrix correctly describes the other chapters, except for strangely describing chapter 6 as “Estimating how likely the two minimal historical hypothesis [sic] are a-priori.” That’s a weird use of the term a priori. Chapter six determines nothing a priori. It determines a conditional probability given certain specified background evidence. That’s called a posteriori.

In my analysis of his critique of Proving History I noted Hendrix does not seem to have an entirely solid grasp of English, and I found this hindered his ability to understand the arguments in my books. He frequently takes them as saying something they don’t, or not saying something they do. These strange descriptions may reflect the same issue. His description of chapter 1 does not appear to understand what the word “survey” means in English, for example. Likewise, the term a priori refers to logically necessary truths, such as that which can be determined from an analysis of terms alone (literally “relating to or denoting reasoning or knowledge that proceeds from theoretical deduction rather than from observation or experience”). As soon as you are drawing conclusions from observed evidence, you are no longer arguing a priori, but a posteriori. (See Wikipedia.)

I do not know why Hendrix confuses “a priori” with the Bayesian “prior probability,” other than perhaps unfamiliarity with the language and technical terminology. Prior probabilities are not a priori propositions; unless you are starting from an unconditioned prior, i.e. a logical demarcation of the probability space before inputting any background knowledge at all (other than logically necessary truths). Bayes’ Theorem is commonly not used that way. The prior probability used in real world applications of the theorem almost always takes into account some body of previous information, called “background knowledge” (the contents of b in the variable P(h|b)). I discuss this in detail in Proving History, and it’s covered in all standard texts on Bayesian reasoning. See also my second point in If You Learn Nothing Else.

Hendrix also shows signs of not having read the book carefully. For example, he says OHJ “does not state in any single place which formula is used for computing the probability of historicity,” yet it does: the Odds Form is shown on p. 598 in the calculations chapter (chapter 12), where I identify it explicitly, and present the equation. It’s even indicated on p. ix on the Table of Figures, as Figure “2. Bayes’ Theorem, Odds Form [ … p.] 598.” I even explain in n. 3 on p. 598 why I used that formula instead of the other that Hendrix instead proceeds with for some reason (which is just as valid, if more awkward). Since all the calculations in chapter 12 are shown and analyzed in the odds form, I have no idea how Hendrix can be unaware of this.

The Accumulated Error Argument

Hendrix starts by attempting to claim my method magnifies errors by a factor of five or even twenty. There are issues with the arbitrariness of how he determines this. But his argument does not apply to my method, so it’s moot anyway. Since my a fortiori estimates are all deliberately erring in favor of historicity, then by his own reasoning, my a fortiori conclusion should be over-estimating the probability of historicity by a factor of five or more. That’s the very point of my doing that. So that means the actual probability of historicity must be substantially less than 1 in 3, by his own reasoning. Which is exactly the conclusion of my book. Hendrix is thus making my argument for me.

Indeed Hendrix proceeds to show exactly that: estimates that we bias even slightly in favor of historicity will skew the end probability far more toward historicity than should be granted. Since that’s exactly what I do, and still I get only a 1 in 3 result, that is why Hendrix is arguing in favor of my conclusion, not against it. What he needs to do, if he wants to challenge that conclusion, is make a case for my historicity-biased estimates to be larger. And that’s precisely how any historian proceeds in any historical argument in history, whether aware of it or not. The extreme difficulty of arguing that higher estimates are at all plausible, translates into an equally extreme difficulty accepting a conclusion higher than the 1 in 3 my historicity-biased estimates entail.

If he could plausibly argue they should be higher, he should just do that, and not erroneously treat historicity-biased estimates as if they were mythicist-biased estimates. By making that mistake, Hendrix’s whole argument topples into what actually is a defense of the very conclusion of OHJ: any adjustment for errors in our estimates will make the a fortiori probability that Jesus existed lower, not higher.

The Trial Argument

Hendrix claims that “If your hair is found on the crime scene and you don’t live there, you are likely guilty of the crime.” I hope he is never a prosecutor, judge, or juror. Because that’s a disturbingly erroneous statement. Your hair can be at a crime scene for a thousand reasons, only one of which is that you committed the crime. Even if your hair is found in a wound, it could be transfer evidence, e.g. if the knife was taken from your kitchen, if the victim had borrowed your sweater and was wearing it, if you had hugged them earlier in the day, if they had brushed against you at the supermarket, and so on. Even if you had brushed against the killer at the supermarket. This is why when we can show any of this is the case or as likely to be the case as anything else, the hair becomes useless as evidence. It no longer is more likely to be there if you are guilty than if you are not. This is how all legal reasoning proceeds. In Bayesian terms, the likelihood ratio then washes out at simply 1/1: it weighs for neither hypothesis.

One correct thing Hendrix says here is that conspiracy theories, and any theory that presumes something is the case that has a low prior probability of being the case, depend on ignoring the resulting diminishment of priors. Hendrix gives the example of contamination at a crime lab producing the mistaken conclusion that your hair was at a crime scene, something that indeed would be very unlikely (usually). But that you hugged your friend in the morning, is not at all unlikely, even on prior probability, the more so if you have evidence you did so then or do so regularly. Thus, all likelihood ratios trend toward 1/1 the less determinative an item of evidence is of either hypothesis. We can’t escape this conclusion with a possibiliter fallacy that “maybe we are mistaken in our estimates of the probabilities” (see PH, index). That’s as unlikely as the lab mistake. Possibly does not get us to probably. “Possibly your hugging the victim in the morning is less likely than your having killed them” does not get you anywhere near “your hugging the victim in the morning is less likely than your having killed them.”

I explain the effect of adding assumptions to get a hypothesis to predict the evidence (it can reduce the prior probability, and quite rapidly as more assumptions are added) in Proving History (pp. 80-81; and index, “gerrymandering”). But when background evidence makes an assumption no longer an assumption but a highly probable event, e.g. when multiple parties attest that you often hugged the victim, then it does not reduce the prior. To the contrary, that background knowledge raises the prior probability of your having hugged them (thus transferring your hair to their sweater at some point) at least as high as the probability of your having killed them. Assuming that was the case therefore no longer reduces the prior probability. Because it is not an assumption anymore. It’s background knowledge. And the prior is always conditioned on background knowledge.

I also explain this fact extensively in Proving History. For instance, on pp. 220-21, I note that the absence of a court record from Pontius Pilate confirming the execution of Jesus is not evidence against historicity, because our background knowledge establishes an extremely high probability that all of those records would have been lost and unavailable even to someone in the second century, much less today. So arguing “we don’t have the record because it was lost” is not an ad hoc assumption we just invented to explain away the evidence. It’s not a conspiracy theory. It is not a “lab mistake” in Hendrix’s analogy. It’s the hug in my analogy. It therefore does not reduce the prior probability (by any amount worth noting). Because we know for a fact that the probability that that record would be lost is virtually 100%. Therefore assuming it was lost has no significant effect on the prior probability of historicity.

As we’ll see shortly, Hendrix repeatedly ignores this fact. He confuses background evidence with unevidenced assumptions—ironically while accusing me of doing that, when I don’t.

Defining Hypotheses

Hendrix shows again that he didn’t carefully read OHJ when he says “a difficulty Dr. Carrier does not address in On the Historicity of Jesus is the basic hypothesis of historicity is conflated with a particular theory for historicity and so it is not clear exactly what the basic theory of historicity or mythicism is.” Far from “not addressing” this, I address it extensively in OHJ, pp. 31-34 and 52-55 (and again on pp. 246-48, specifically addressing this “Complexity Objection,” under that very title!). I explain in detail why we need the terms I reduce them to, every single one; and I explain in detail why all remaining hypotheses can be excluded because they have vanishingly small priors.

Meanwhile, Hendrix does a worse job by trying to strip the hypothesis down to just “there once lived a man called Jesus who founded a religious group which stands in a causal relationship to Christianity today.” Many scholars argue Jesus neither founded nor intended to found a movement after him, yet nevertheless existed, and that his death only inspired a subsequent movement (which was actually founded by one of his students). So we can’t use the new hypothesis Hendrix proposes—it excludes too many historical Jesuses. It likewise includes too many historical Jesuses. There were certainly many men named Jesus who played roles in developing the Christian movement, even at its origin, as Jesus was a common name of the time. So that one existed in the original cult does not get us to “the guy they claimed was crucified and were worshipping” existed.

That’s why minimal historicity has to include all three terms I identify: Christianity was founded by men who followed a man at some point named Jesus, whom they claimed was executed, and then worshiped as a conduit to the divine. If you remove any one of those terms, you will be looking at the wrong Jesus, not the one we are interested in. If the Jesus Paul says they were worshiping and obeying the commands of was not the Jesus they were claiming had died and whose followers started the movement after his death, then that latter Jesus is not a relevant Jesus. It’s someone else.

It gets even worse when Hendrix tries to reduce the hypothesis to literally just “Jesus was a historical person.” Really. So. Which Jesus? There were hundreds of them. Including several in the early Christian movement. You can’t just state your hypothesis as “Jesus was a historical person.” You have to explain which Jesus you mean. That specification therefore becomes an inseparable part of the hypothesis. You can’t get away with “hiding” necessary elements of the hypothesis behind vague words like “Jesus.” Jesus ben Ananias? Jesus ben Jehozadak? Jesus the Sanhedrist? Jesus the High Priest? Jesus the Ship’s Captain? Jesus the Cretan? You have to specify. So I did. That’s correct procedure. Whatever Hendrix is doing is not.

That Hendrix thinks he is improving on my work by making it less rigorous and more misleading and ambiguous does not give me much confidence in his ability to correctly apply Bayesian reasoning to questions in history.

Completing the “Prior Probability Space”

Hendrix notes that by demarcating the hypothesis space with several conjoined terms, like “this Jesus was originally believed to have endured an ordeal of incarnation, death, burial and resurrection in a supernatural realm,” I am leaving some of the possibility space unaccounted for. For example, when we combine my minimal historicity with my minimal mythicism, there are still several hypotheses left over, so those two hypotheses I am testing do not logically exhaust the entire prior probability space. Contrary to what Hendrix claims, I explicitly acknowledge this in OHJ.

This is exactly what I myself point out, first on page 30:

‘Jesus was a historical person not mythicized’ [and] ‘Jesus was a mythical person not historicized’ … even collectively, consume a vanishingly small piece of the prior-probability-space (certainly less than a one in a million share). They can therefore be ignored.

And then for the five elements of my minimal mythicist hypothesis (pp. 53-55):

Unlike the minimal theory of historicity, however, what I have just said is not strictly entailed. If ‘Jesus Christ began as a celestial deity’ is false, it could still be that he began as a political fiction, for example. But as will become clear in following chapters … such a premise has a much lower prior probability … and a very low consequent probability … . Although I leave open the possibility it may yet be vindicated, I’m sure it’s very unlikely to be, and accordingly I will assume its prior probability is too small even to show up in our math. This decision can be reversed only by a sound and valid demonstration that we must assign it a higher prior or consequent, but that I leave to anyone who thinks it’s possible. In the meantime, what we have left is Premise 1. … This same conclusion follows for Premise 2, which could also be false and mythicism still be true, but only on the alternative hypothesis that everything said about (and said to have been said by) Jesus was an outright and deliberate fabrication (or the product of such a deranged reading of scripture as to beg every question of why the movement would even have found followers), which again has a very low prior probability (certainly much lower by far than Premise 2), and a very low consequent probability … Premises 3 and 4 could similarly be denied and mythicism still be true, so long as we posited that the founders of Christianity hallucinated the entire life and fate of an earthly Christ, or outright lied about it ever having occurred. But again, either possibility has an extremely low prior probability … Finally, Premise 5 is already an effective certainty, as it is true even if historicity is true, and is so well verified in background evidence that its prior probability is as near to 100% as makes all odds. So the possibility of its being false will not be an issue. Since Premise 5 is certainly true, and the prior probability of any of Premises 1 through 4 being false and historicity still not being true is vanishingly small (certainly less than a tenth of one percent by any reasonable estimate), if I assign ~h to be the theory defined by Premises 1 through 5, I can safely assume that h entails historicity (given my minimal definition of historicity … ) and that these exhaust all relevant possibilities, and therefore I have a proper binary test, h and ~h, just two hypotheses to compare against each other, such that if one is false, the other is true. Certainly, when framed like this, technically ~h (non-historicity) must also include all Jesus myth theories not defined by Premises 1 through 5 (that is, all theories of the evidence for Jesus that entail historicity is false and at least one of Premises 1 through 5 is false), but since their prior probability (even collectively) is surely less than a tenth of one percent (as I just reasoned), and their posterior probability not sufficiently high to make enough of a difference (especially in relation to minimal historicity), these theories share such a small portion of the probability-space occupied by ~h that they can simply be ignored. In other words, if ~h (as I have minimally defined it) is false, it’s simply the case that historicity is probably true.”

As all of that argument, ignored by Hendrix, entirely refutes Hendrix’s argument about demarcating the prior probability space, I should hardly need say any more on the matter. But as he seems to be confused about how this works, others may be as well, so I will take the time to explain what those paragraphs are saying and why it is correct.

Prior Probability Is a Relative Probability and Conditioned on Background Knowledge

If my minimal historicity combined with my minimal mythicism leaves a third segment of the possibility space left over, containing all other possible theories, but that section in its entirety is known on background evidence already to occupy a vanishingly small portion of that space (less than a tenth of a percent), then we no longer have to concern ourselves with that extra possibility space. We could. We could have three hypotheses and tediously continue the math for that third segment of the possibility space, but it would be a waste of time, as all we would ever get for it is absurdly low posterior probabilities, and there would be no significant effect whatever on the probabilities for the other two hypotheses I conclude with in the book. Because the effect had would be below the resolution of rounding that I employ and would thus be invisible.

The mistake Hendrix makes here is to forget that prior probabilities are relative probabilities, not absolute probabilities. Adding assumptions to a hypothesis only decreases the prior probability of that hypothesis if it increases the prior probability of an alternative hypothesis. So, for example, adding my term “this Jesus was originally believed to have endured an ordeal of incarnation, death, burial and resurrection in a supernatural realm” does not significantly reduce the prior probability of non-historicity because adding it only gives some of the prior probability space back to other non-historicity hypotheses. Adding it does not increase the prior for historicity. And what I then observe is that even the amount it increases other non-historicity hypotheses is negligible.

For instance, suppose we had no background knowledge, and demarcated h from ~h, or h1 from h2, as 50/50, even odds the Jesus we are asking about existed or not. Then we added a term a to ~h, making an h3 (so, ~h + a = h3), and then we made h2 into ~h when a is false (so, ~h + ~a = h2). And suppose this added term a itself also has a 50/50 chance of being true, something as likely to be true as not, we don’t know more than that. Then we would have a demarcation of priors equal to P(h1) = 0.5, P(h2) = 0.25, and P(h3) = 0.25, but h2 and h3 are both ~h, so P(~h) = P(h2) + P(h3) = 0.25 + 0.25 = 0.5. As you can see, adding the term did not increase the prior probability of h1. It had no effect on it at all. Hendrix somehow has not noticed this.

For a more apt analogy, if we return to Hendrix’s trial analogy, if we listed all the possible ways that your hair could be at the scene, and we then proceeded to show on background evidence that all the other ways it could be there were vastly less probable than a lab mistake, positing the lab mistake would no longer reduce the prior probability of your hair innocently being there, by any appreciable amount. It only would have that effect if we knew there were more likely ways of it being there. Like being guilty. But if, for instance, we surveyed legal cases and found in 99 out of every 100 cases the lab mistakenly placed a hair at a scene, positing that that happened in this case also does not produce any significant reduction in the prior probability of your being innocent.

Hendrix is trading on the assumption that labs almost never make such mistakes, that the prior probability of that is vanishingly small. That’s how we use background knowledge. This is exactly what I am doing when I rule out all other mythicist hypotheses, and end up with only one occupying half the possibility space (before inputting further background knowledge). In other words, after demarcating ~h into h2 and h3, I find background knowledge shows that h2 is like a lab mistake: vanishingly unlikely. That leaves almost the entirety of the 0.5 space that is occupied by ~h (which includes h2 and h3) occupied by h3 (as the portion of that space occupied by h2 is too tiny to even show up in my math). In other words, h2 is the analog to Hendrix’s lab mistake; not h3. That’s why I reject h2 and go with h3. Once again, Hendrix is making my argument for me.

Thus, if we eventually find that only 1 in 3 Jesus-like figures has in the past turned out to be historical, then 2 in 3 were not historical. There is no getting around that. Then, if all the ways Jesus can be not historical have vanishingly small priors except for “being believed to have endured his ordeal in a supernatural realm,” then adding “being believed to have endured an ordeal in a supernatural realm” to the hypothesis produces no significant reduction in the prior probability of non-historicity for Jesus. It remains 2 in 3. Because all the alternative ways for him to not exist have such small priors, that their effect is invisible at that resolution, showing up only several decimal places out—if we wanted to increase our resolution to so many decimal places, but there would be no point in doing that.

Hendrix thus forgets that prior probabilities are relative probabilities. He often acts as if he would insist the prior probability of a wealthy person having gotten rich by winning the lottery is the probability of winning the lottery, when in fact it is not, it is the frequency with which rich people got rich that way. If, for example, the only way anyone could ever get rich was by winning a lottery, the prior probability of having gotten rich by winning the lottery would be effectively 100%, even if the probability of winning a lottery were one in a million.

Analogously, Hendrix acts as if the prior probability of Jesus not existing because of “being believed to have endured an ordeal in a supernatural realm” is the probability of “being believed to have endured an ordeal in a supernatural realm,” when in fact it is not, it is the frequency with which relevantly similar non-existent people became historicized that way. If, for example, the only way any non-existent person was ever historicized was by “being believed to have endured an ordeal in a supernatural realm,” the prior probability of not existing because of “being believed to have endured an ordeal in a supernatural realm” would be effectively 100%, even if the probability of “being believed to have endured an ordeal in a supernatural realm” were one in a million.

But in this case, we have additional background evidence that narrows the field. For instance, though not every historicized person was “believed to have endured an ordeal in a supernatural realm,” every historicized mystery-cult savior god we know the full story of was (as background knowledge establishes: OHJ elements 31, 36, 40, 45, 48). And Jesus was a mystery-cult savior god (as background knowledge establishes: OHJ elements 13, 14, 18). Adding it therefore does not reduce the prior probability that Jesus didn’t exist. That’s simply the only way someone like Jesus (e.g. a historicized mystery-cult savior god) starts their existence. Other than for a few other ways that are so extraordinarily rare as to not even show up in our math at the resolution we are using.

Hence this is not like the lab mistake hypothesis; it’s like the hugging hypothesis. Those other ways Jesus could not exist are like the lab mistake hypothesis; and that’s why I reject them, because they vanish from the math, as even Hendrix would recommend (as that’s what he recommends for the lab mistake hypothesis). But we have abundant background evidence that this is the typical way mystery-cult savior deities start their existence; just as if we had abundant background evidence that we often hugged the victim. Therefore, Hendrix has his reasoning exactly backwards. And all because he isn’t reading OHJ carefully; and is forgetting basic details like these, of how a prior probability space gets demarcated.

So when we get later to the discovery that background knowledge establishes that no fewer than 2 out of every 3 people like Jesus didn’t really exist, we have our prior probability for ~h. And when we break ~h into h2 and h3 and discover our background knowledge establishes h2 as extremely unlikely, almost the entirety of the space occupied by ~h is then occupied by h3. And that’s why it’s the hypothesis I chose to test against historicity. When we look at how all those other non-existent people began, they began in various ways (e.g. political fictions, mythic pasts, ordeals in supernatural realms). When we look at the background evidence for Jesus, we can see that it is vanishingly unlikely that he began as a political fiction or someone who died in the distant past; that means almost all of the remaining probability space for ~h is occupied by the “supernatural realm” condition. Likewise if we proposed causes that have never been in evidence for anyone, or are even less likely than lab accidents—for instance, wholesale lying about Jesus having recently lived and died in Judea (which we can conclude has a vastly small prior from vast background knowledge regarding human and societal behavior).

Thus the “supernatural realm” condition does not reduce the prior probability that Jesus didn’t exist. It is in fact the only condition on which he could not have existed. Because all the others are extraordinarily unlikely. This is the consequence of prior probabilities being relative probabilities. They must be determined relative to all other competing hypotheses. Not in isolation from them. This is also the consequence of prior probabilities being conditional on background knowledge. Not in isolation from it.

Hendrix has missed all of this. He does not see how background evidence determines the result: e.g. that similar gods died in supernatural realms and had myths written of them placing their ordeals on earth; that the entire database of human and societal behavior renders the alternative mass-lying hypothesis vanishingly small before we even consider it further; etc. He confuses the effect of background knowledge on frequencies, e.g. his analogy of the lab mistake actually matches the non-existence hypotheses I reject as having vanishingly low priors (and thus he is actually making my point for me), whereas the elements I keep match the hugging hypothesis (as being demonstrably frequent for comparable religions of the time). And he does not see how relative probability entails the result: e.g. how when our background knowledge establishes only a 1 in 3 chance of historicity for persons of the same reference class, if the only way Jesus could be non-historical is to have been supernatural, then his having started supernatural has a prior probability so near to 2 in 3 as to make no difference.

Hendrix therefore has presented no relevant challenge to these conclusions.

Being Confused about Background Evidence

Hendrix ironically accuses me of being confused about what counts as background evidence, when he is the one who is. For example, he asks how the element of the hypothesis, that “subsequent” Christians believed Jesus historical, is in our background knowledge. It does not occur to him that the entire history of Christendom is in our background knowledge. We know second century Christians believed Jesus historical. That is not evidence pertinent to the hypothesis because none of those Christians had any access to the truth of the matter. So their believing that is as likely either way. Just as for Hercules, Romulus, Osiris, Inanna, Bacchus, Marduk, Asclepius, and so on. For all of them it is a true statement that “subsequent pagans believed they were historical persons.” We know that to near 100% certainty on background evidence alone. Before we even ask what evidence there is for or against that belief. So Hendrix cannot challenge this; it is already a certainty on our background knowledge, just as much for Jesus as for every other deity he resembles.

Of course, some second century Christians even attacked fellow Christians who were claiming Jesus didn’t exist (on earth), by fabricating evidence that he did (e.g., 2 Peter: OHJ, pp. 350-51). But I pulled that out of background evidence and placed it into the determining evidence (in chapter 8, though I end up assigning no weight to it either way). Because everything that is not in e is in b, and everything that is not in b is in e, without remainder. So what we put in each won’t matter, as long as we leave nothing out, and don’t put anything in both. Hence my remarks on p. 395 regarding how, even if the Gospels are 100% mythical, that fact alone has no net effect on the historicity of Jesus:

There is one important exception to this point: the Rank–Raglan data, which was used to construct our prior probability (in Chapter 6), because it can be correlated with enough examples to derive an actual probability that such data would accumulate for a real man. But we have already employed that evidence in our calculation (and only if we didn’t would we introduce it here: see Chapter 6 and the end of §2 in Chapter 12). Thus, the mythic character of the Gospels overall will affect our estimate of historicity. But only as much as it already has.

Notably, Hendrix shows no sign of having read that paragraph or even knowing it exists in the book. He even burns entire sections of his critique on an argument that is refuted by this paragraph (e.g. his 5.4.1). More evidence of his careless reading of OHJ.

Hendrix identifies no actual point anywhere in OHJ where I double count evidence as if it were in both b and e. In every case, I clearly demarcate what is in e, and do not use it again as if it were in b. Likewise the reverse. Indeed, he strangely says “The addition of additional elements to our basic theory is justified by essentially adding parts of the evidence to the background knowledge” yet “what is added is never stated.” This is false. I explicitly state every item of evidence I have placed in e. I even label it and assign a probability to it. Accordingly, anything I do not label and assign a consequent probability to is in b. I even explicitly discuss how I demarcate the contents of e and b on p. 59 (a page Hendrix seems not to have read). So it is false that I never state the demarcation. I am extremely clear and specific as to what’s in e. And by logical necessity, all other facts must be in b. Because the contents of e and b must exhaust all existing facts.

Indeed, by method of iteration (see Proving History, index), as soon as you output a posterior probability with any e, that e enters b in any further iteration of the equation inputting more evidence. And one could simply do that if they wished: start with a neutral prior (50/50), and put the Gospels entire in e (including the Rank-Raglan data), and generate a posterior probability, and then use that as the prior probability for the next input of evidence. The result will be identical. And I even say this explicitly in chapter 6, and show why mathematically either procedure comes out the same. It is therefore disingenuous of Hendrix to pretend otherwise.

Ignoring How the Reference Class Is Constructed

Hendrix has further erred here in not paying attention to how carefully I constructed the reference class I used to derive the prior probability of historicity for Jesus.

Hendrix says, “It seems plainly obvious to me at least that an early belief Jesus was historical in the Christian community…is easier explained if we assume Jesus was historical than if we assume he was not.” That’s refuted by every other example in the largest available reference class. In Chapter 6 I employ the Rank-Raglan class, detailed earlier in element 48 (OHJ, pp. 229-34), where I assemble fourteen persons, who exhaust all persons who fit that class (minus Jesus), all of whom were believed to be historical, yet none of whom were. Even at the most absurdly generous, we could maybe say 1 in 3 were (and that’s by literally just making up examples, assuming historicity without evidence). So clearly it is not the case that later belief in their historicity “is easier explained if we assume” they were historical. The evidence simply does not bear that out. Because none of them is plausibly historical.

I suppose Hendrix might be caught here in a chronological compression fallacy, confusing a hundred years later as being soon after an event, when even fifty years was an average human lifespan (element 22: OHJ, pp. 148-52). He is confusing modernity with antiquity, anachronistically imagining modern lifespans and documentation-access as existing two thousand years ago, and thus assuming anyone in the second century had access to ways to test whether Jesus existed a century before. When not only is that extremely unlikely on background knowledge alone, it’s unlikely on the evidence: for if they did have such access, we should have access to it as well, as surely it would have been preserved, or at least referenced. So the fact that they give us none, is confirming evidence that there was none.

I show this even more clearly in my discussions of Papias and Hegesippus, for example (in chapter 8.7-8). It is not possible that there were still people who knew Jesus personally in 100 A.D. who never in their entire lives wrote about it (or that no one had ever read or heard of anything they wrote). It is not even possible that there were still people who knew the Apostles personally in 100 A.D. who never in their entire lives wrote about it (or that no one had ever read or heard of anything they wrote). This would not count as evidence against the historicity of Jesus if we were to count it so (hence I would assign it no weight in my survey of extra-biblical evidence in chapter 8). But it certainly counts against any presumption that people in the second century had access to special data that makes their belief any more likely to be true. Their belief is therefore useless as evidence. It tells us nothing about whether or not Jesus existed, any more than the popular belief that Dionysus existed does. Hendrix is simply wrong to claim otherwise.

Hendrix rightly rails against basing probability judgments on undemonstrated assumptions. But he points to none that I base any probability on. All my judgments are based on demonstrated facts about the ancient world, thoroughly presented and documented (in chapters 4 and 5, consuming nearly 200 pages). Instead it is Hendrix who bases a probability judgment on an undemonstrated assumption: that second century persons had access to better evidence for the historicity of Jesus than we do. That is not in evidence. And it is substantially contradicted by the evidence we have. It is therefore a mere presumption, and a very unlikely one at that (see my remark above about Pilate’s records, for example). Therefore, that Jesus was not historical yet came to be believed to be historical remains as likely for him as for everyone else in his same reference class, like Hercules, Osiris, Dionysus, Moses, and so on. They were all non-historical yet came to be believed to be historical. In fact we don’t have any demonstrated instance of persons in the same reference class actually being historical. Thus, their actually being historical is not a better explanation of later belief in their historicity. No more for Hercules or Dionysus or Moses or Osiris than for Jesus.

Our background knowledge establishes that all non-existent persons (in that era and social system) sharing common characteristics with Jesus came to be believed to be historical. All of them. We must condition our probability estimates on that knowledge. Hendrix cannot evade this fact with armchair intuitions that are not in evidence or even contradict the facts of history. If we had Christians like Paul who within years believed Jesus was recently walking the streets of Judea, only then would Hendrix have a point—although it would not be a point about priors. It would be a point about likelihoods. For that would be evidence that Jesus existed. Precisely what we don’t have.

Using the Rank-Raglan Reference Class

Hendrix deploys a fallacy of credulity by saying that he can’t understand my argument that “if we only had the Gospels we should conclude Jesus most likely did not exist” because the Gospels portray Jesus as just like fourteen persons, and none of them existed. He says of himself, “I am not a historian, but I simply have great difficulties accepting this conclusion.” That’s strange. Because he claims to be a Bayesian. And you don’t need to be a historian, only a Bayesian, to recognize that when a hat contains fifteen beans and we know fourteen of them are black, the prior probability any bean you draw from the hat will not be black is extremely low. And prior probability requires us to treat all the beans alike. You can’t privilege Jesus. The prior odds that Hercules or Osiris were historical have to be the same prior odds that Jesus was. Because they are in the same hat.

Imagine Hendrix arguing that if all we had were the legends of the twelve labors of Hercules, we should assume Hercules existed; that if all we had were the legends of Osiris traveling Egypt, we should assume Osiris existed. This doesn’t make sense. Least of all because we have abundant evidence they didn’t exist; because we don’t “only” have their legends. We have earlier documentation of their supposed times and regions. Most gods and heroes, by far, did not exist. Yet had stories told of their adventures on earth, set in specific historical times. Any Bayesian worth their salt should have no difficulty seeing the point: if all other gods and heroes like that have such stories yet did not exist, then another god like that having such stories cannot be evidence they existed. To the contrary, we have to stick with the prior odds: usually, gods with stories like that, don’t exist.

That’s how background evidence conditions the prior. You can’t gainsay this by ignoring all this background knowledge and what it entails. No matter how much your intuition rages against the evidence, your intuition has to go hump. The evidence is king.

You simply have to give the same prior to Jesus that you would give to Moses, Hercules, Osiris, or any new god or hero we discovered who was painted the same way with similarly structured legends. Of course, there could be evidence that sets Jesus apart as special. Evidence that establishes he did exist, unlike all those others. But absent that evidence, if all you have is the same evidence you have for Hercules, Moses, Osiris, etc., then you have to accept the prior as all you know of their probability of existing. So you have to go on to look and see if we have special evidence for Jesus that we don’t have for Moses, Hercules, Osiris, etc. That’s what you do next. But until then the prior remains unchanged, until you find that special evidence, and use it to update your prior. Which then becomes your posterior.

Instead of doing that—the correct thing for a Bayesian to do—Hendrix becomes an even worse Bayesian when he deploys yet another possibiliter fallacy (see Proving History, index), stating that “if” the Gospel authors just mapped Rank-Raglan features onto an actual person’s story, then we’d have a historical person with those features. He even says “This seems like a perfectly sensible argument.” It is not. Because the question remains: How likely is that, rather than the reverse? Because you can say exactly the same of Moses, Hercules, Osiris, Bacchus, anyone in the set. Yet it would be illogical to say “because they might have been historical, and only had those features mapped onto them, therefore we should assume they were historical.” The correct question is: How often did people map those features to real people vs. non-existent ones? And the evidence shows the answer to be: Almost never (if not in fact actually never). Even actual persons who had some of those features mapped onto them (Alexander the Great, Sargon of Akkad) did not have more than half of them mapped to them, much less nearly all of them. In every prior case when someone has had more than half of them mapped onto them, they have turned out to be a non-existent person. This tells us that any new persons about whom that is the case, will also just as likely turn out to be a non-existent person. Because that’s what’s happened time and time and time and time again. Without any known exception, in fact.

That it’s still possible Jesus is the exception, the one actual person on whom that many attributes were mapped, is already accounted for in the converse probability. But we can’t change that probability from what the evidence shows it actually is (at worst 1 in 15, though I highly bias the estimate toward historicity by allowing it to be 1 in 3) merely because we are uncomfortable with that fact. We have to keep it where the evidence shows it actually is. To prove Jesus the lone exception requires evidence. Not presumption. Not armchair intuition.

Hendrix’s arguments for judging Jesus differently than other members of that set don’t work for Hercules, Osiris, Moses, or anyone else in the set, and don’t work for Jesus either. They, too, all have different features from each other—not all, for example, started life in a supernatural realm—yet still have the same prior probability of existing. The “they were different, therefore they aren’t the same” argument is a fallacy, one that would destroy all reference classes in the universe. Because everything is both different and the same. Literally everything that exists. Once we see that no more than 1 in 3 members of that set have historically existed, we must conclude that’s the prior probability any member of that set existed. What remains to ask is not whether 2 in 3 didn’t exist—that follows necessarily. What remains to ask is how. And that can vary. It does not matter if, for example, Asclepius did not start life in a supernatural realm. The possibility that Jesus also did not, is already included in our numbers: as an alternative hypothesis with such a vanishingly small prior for deities more like Jesus that it doesn’t show in our math at the resolution used in OHJ. Hendrix is thus wrong to claim I am not accounting for that. I am. And I explicitly say so. And he has no argument against the point.

Mucking Up the Reference Class

Hendrix makes more of these kinds of mistakes, leaning on possibiliter fallacy after possibiliter fallacy. For example, he tries his own “alternative class objection” (a ploy I already refuted in OHJ, under that very heading, on pp. 245-46), using a “recent person” class (a ploy I also already refuted in OHJ, under the heading of “rapid legendary development,” on pp. 248-52), not noticing that he doesn’t have any members of the required set: Recent persons who are Rank-Raglan typed (and indeed, by his own reasoning, “who were rapidly Rank-Raglan typed”). That set is empty (but for one member: Jesus). Therefore he has no data with which to construct a prior probability with this class. You can’t just make shit up. No data, no result. You have to move on. (Whereas, by contrast, that it “can’t” happen so fast is refuted by the cases of Ned Ludd, John Frum, and Tom Navy: OHJ, pp. 9-11 & 159-63.)

Hendrix similarly confuses the Josephan Christs Class (OHJ, pp. 245-46) with the Testimonium Flavianum, in which Jesus is not depicted as a Josephan Christ. Somehow Hendrix thinks that what makes a Josephan Christ (engaging in apocalyptic activities that evoke Joshua’s original conquest of Israel) is in the TF, when it is not. So he actually misidentifies the TF as belonging to a reference class it does not belong to. The TF never relates Jesus in any way that resembles the Josephan Christs (ironically, this includes the TF actually calling him a Christ; because Josephus never calls the Josephan Christs “Christ”; that’s not a word he ever uses in all his writings). The TF does not depict Jesus as an apocalypticist, or as a reborn Joshua, or as engaging in any apocalyptic messages or activities, nothing in fact that matched the messianic standard represented by the Josephan Christs (OHJ, pp. 67-73). This is, of course, yet one more reason why we know Josephus never wrote the TF. But even if we were to bizarrely suppose he did (contrary to all the evidence: OHJ, pp. 332-42), the TF does not describe a member of the Josephan Christ reference class. So Hendrix cannot use it as such.

Hendrix’s final sections are largely just full of speculative textual exegesis that he has no expertise in and that ignores nearly everything argued and all the scholarship cited in OHJ on the matters he attempts to critique. I find those sections too useless and uninformed to warrant any further response. Just read OHJ and, if you need more, the scholarship it cites on any given point. Likewise his concluding remarks are all based on the errors of his previous sections, and thus dissolve on noticing that.

Conclusion

Hendrix’s review is confused and lacks any critique of the actual contents of OHJ. It frequently ignores the contents of OHJ that already refute him; it identifies no actual errors of logic, mathematics, or fact pertinent to the actual argument in OHJ; and it makes arguments that actually reinforce the conclusions of OHJ. He errs in not understanding how my prior probability is constructed as it should be, as relative to all other competing hypotheses including those excluded by the two I test, and how my priors are conditioned on actual background knowledge amply demonstrated in OHJ, instead of the unevidenced assumptions and uninformed intuitions Hendrix tries to replace those facts with.

Hendrix uses false analogies (e.g. equating my ruled-in hypothesis as analogous to lab accidents, when in fact it is my ruled-out hypotheses that are analogous to lab accidents). He uses possibiliter fallacies (he assumes several times that when something is possible, e.g. that a dense Rank-Raglan matrix can be mapped onto a historical person, we should therefore take it as probable). He confuses historicity-biased probability estimates with mythicism-biased estimates. He tries to replace rigorously defined hypotheses with poorly defined and hopelessly ambiguous ones, and advocates that as an improvement. He ignores all my clear and careful statements about how I am demarcating evidence, and then accuses me of not saying how I am demarcating evidence and of taking no care in it. He rejects reference class sets that have many well-documented members, and tries to replace them with reference class sets for which he has no data at all. And he ignores background knowledge and tries to replace it with intuitions contradicted by that knowledge (e.g. of how often a dense Rank-Raglan matrix has been mapped onto a historical person; of lifespans in antiquity being half those of today and access to documentation of pertinent events almost non-existent; etc.).

In all, Hendrix’s critique is a travesty of error and confusion. He does not read carefully. He complains about lack of rigor then violates his own standards of rigor. He doesn’t understand the needs and requirements of historical argument. He locates no instance of my double-using evidence in e and b. He locates no instance of estimation error relevantly affecting my a fortiori conclusions. He locates no instance of any element of either hypothesis being improbable relative to all other variants of those hypotheses. And he presents no evidence that the prior probability of strong Rank-Raglan class members being historical is any different than I find at the a fortiori side—which is 1 in 3, not the much lower number he keeps repeating, which is my lower not upper bound—and he presents no evidence we should treat Jesus differently than any other member of that set.

All in all, a useless review.