There Probably are Bayesians in Foxholes

Many years ago, I almost fell into bad company.  I frequented a philosophy channel on IRC that included a small, but very vocal band of what I like to call Randians – primarily because they didn’t like being called Randians.  These Randians preferred to be called objectivists and apparently their greatest love in life was sticking it to subjectivists.  Boy, did they hate subjectivism!

(Why Randians?  Because they were devotees of Ayn Rand and her philosophy of "objectivism".  I have, since that time, had an abiding distaste for Ayn Rand and anyone who adores her.  I do understand that in some instances a thoroughly reviled person like Ayn Rand may be misunderstood, or misjudged, and there is the possibility that, despite appearances, such a person does in fact have redeeming features.  For example, they might like puppies and kittens.  Ayn Rand, however, delighted in ripping the legs off puppies and kittens and throwing them at small children that she had cast into a deep well at the bottom of her garden.

If I were given the choice of spending eternity with Ayn Rand or William Lane Craig, I would choose laughing boy, despite being aware that the notion of spending eternity with anyone would indicate that he was right about the whole god thing and he would undoubtably spend some excruciating proportion of that eternity crowing about how he was right and I was wrong.  But at least we would both be in hell.)

The odd thing was that, at the time, when I searched for these subjectivists, they didn't seem to exist.  The Randians appear to have constructed an army of straw men to attack in their objectivistic fervour.  Sure, anyone who crossed them would get labelled as a subjectivist, but this term appeared to be more pejorative than accurate.

A similar sort of one-sided battle appears to be underway between Bayesians and frequentists.  Now perhaps the baying of the Bayesians is a little more accurate than that of those objectivists, perhaps there are people out there carrying the torch for frequentism, but I've not seen any evidence of it.  It seems to me that in some instances a frequentist interpretation of probability is appropriate and in other instances a Bayesian interpretation is appropriate.  See the second last page of this – note however, that the author is a statistician, the sort of person who uses probability all the time.  In other instances, such as the on-going cat fight between Luke Barnes and Richard Carrier, the participants of a recent probability-centred spat are not statisticians – they are a cosmologist and a historian.

What truly boggles the mind is the fact that Barnes has recently devoted an entire post to lambasting Carrier on what started out as a response to short statement from Jeff Lowder in support of a criticism from Barnes, all predicated on a single word.  Carrier wrote (in his essay in "The End of Christianity"), my emphasis:

Bayes’ theorem is an argument in formal logic that derives the probability that a claim is true from certain other probabilities about that theory and the evidence.

To say that Bayes' theorem is an argument is possibly a bit of an awkward way of putting it.  It could, possibly, be written as an argument in formal logic, in much the same way as 1+1=2 was by Russell and Whitehead, whose work Carrier references, but that's not really how Bayes' theorem is thought of.  So, Carrier's claim is not worded particularly well.  No big deal.  Barnes however leapt gleefully onto that fact, spending some considerable time in savaging it and Lowder later concurred that Carrier's wording wasn't completely accurate.

Sadly, rather than 'fess up to having (at least) one sentence in his essay that was a tiny bit stilted and moving on, Carrier gracefully conceded that Bayes' theorem might not be an argument per se, but then went on to claim it is the form of an argument (after having claimed, apparently off the cuff, that one simple derivation of Bayes' theorem is the derivation of Bayes' theorem rather than a derivation).  He subsequently went on to point out that the issue is not so much the validity of Bayes' theorem (which no-one appears to be contesting) or the formulation of Bayes' theorem (which, again, no-one appears to be contesting), but rather the issue is what may be input to the equation that is the expression of Bayes' theorem.

In effect this was saying "any argument about Bayes' theorem, the derivation of Bayes' theorem or the description of Bayes' theorem is moot, because the argument isn't about Bayes' theorem itself but rather about what we bring to Bayes' theorem".

So, did Barnes pick up on this implied appeal to stick to what is relevant and not get bogged down in irrelevant detail?  Of course not.  His latest (and perhaps last) attack on Carrier is focussed, laser sharp, on Carrier's use of "the" rather than "a".  In the conclusion, Barnes challenges Carrier to release a new variant of probability or, in effect, choose a side: "Bayesian" or "frequentist".

What I find even more absurd is Barnes' statement in the comments:

(Carrier)’s not a frequentist. Frequentists don’t believe that prior probabilities exist, but Carrier does.

What?  Are alternate interpretations of probability now to be considered as competing ideologies?  Here Barnes appears to either have forgotten what he wrote in his piece 10 Nice things about Bayes' Theorem or he is accusing these mythical frequentists of being complete morons.

Prior probability is a defined term.  It's not something like climate change, free will or the Loch Ness Monster – it's not something that you can really question the existence of (complete morons aside).  Perhaps it's a term that you can, under certain circumstances, question the utility of – like the term "European" (do you mean people who have some combination of the SLC24A5, SLC45A2 and HERC2/OCA2 genes or people who currently reside on the continent of Europe, or people who define themselves as members of the European Union, or something else?) – but you'd be crazy to deny that prior probabilities ever exist.

It seems completely bizarre to me that there are these mad keen Bayesians, apparently snug in their foxholes, taking the occasional pot-shots at their enemies, the dastardly frequentists, totally oblivious to the fact that – in the right circumstances – these "frequentists" would be more than happy to utilise a Bayesian interpretation.  It reminds me somewhat of those theists who become defensive at the mere mention of even the mildest expressions of atheism, as if the lack of belief on the part of one were necessarily a full-scale, frontal attack on the other.  (Note that this is a position which only encourages some of the more mildly oriented atheists to move towards the militant position.  It basically becomes a question of self-defence.)

Oh, hang on.  These people, the manic Bayesian defenders and the aggressively defensive apologists, they seem to be one and the same.  What was the likelihood of that!

Anyway, Barnes has stated that he might no longer be attacking Carrier.  I don't know if that will be the case though.  I think I identified a misplaced comma in one of Carrier's latest sentences and that could be strung out into a couple of a rants.  Don't you think so, Dr Barnes?

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(Yes, I do appreciate the irony in that final comment, since I have written numerous articles sniping at Barnes, spinning dross from essentially nothing.  But I am small fry, a mere gnat, a bit-part player while Barnes and Carrier are more substantial actors.  That's not to say that my inconsequentiality renders my criticisms invalid though, even if Barnes may well choose to ignore them.

And, again, yes, I do realise that I have a sample size of one here, regarding the correlation between Bayesian defenders [or at least attackers of frequentism] and apologists.  I just provided an example, that was not intended to be conclusive evidence in support of my case.  It happens to be a nice coincidence that the anti-frequentism argument is provided here in the context of a defence of fine-tuning as an argument for god.)

Lucky Luke and the Twenty Royal Flushes (Another Parable)

Little Luke Junior (also referred to as "Cool Hand" Luke after that incident with the ice cream) loved nothing more than to sit at the knee of his father, the legendary "Lucky" Luke, and have him recount the story of the day he had dealt twenty royal flushes in a row.

Lucky Luke would start with rambling stories about his past adventures, how smart his horse at that time was, how stupid his dog was, how it would still be years before he and Luke Junior's mother would meet and how, even to this day, he sometimes misses the first cigarette of the day (usually accompanied by an attack of coughing and spitting blood).  Then, once warmed to his topic, he'd talk about how, all those years ago, he met a gambling man whose penchant for evil eclipsed that of Black Bart (who was actually a nice gentleman who just happened to commit a stage-coach robbery here and there).

This character, "No-Eggs" Oliver, had little going for him except his reputation of meaningless violence and OCD.  His final obsession, the one that brought Lucky and No-Eggs together, was to see 20 royal flushes dealt in a row.  He rode up and down the country, visiting saloons, bordellos and gambling dens, challenging people to deal 20 poker hands from 20 individual packs of cards.  He rode quickly and, quite frankly, had nothing else to do with his time, so he extended this challenge to millions upon millions of people.

The challenge went a little like this: "Shuffle these 20 packs of cards and deal a royal flush from each.  If you fail, I shoot you in the head.  If you don't try, I shoot you in the head.  If you cheat, I shoot you in the head."

So, naturally, they all tried, and they all failed.  Until "Lucky" Luke (who until that time was only known as Luke).  He tried and he succeeded.  No-Eggs, who was getting rather old by this time, having killed millions upon millions of unsuccessful croupiers, was so astonished that, despite a lifetime spurning eggs due to the possibility of cholesterol and the suspicion that even "free range" eggs might not really be free range, suffered an enormous cardiac arrest and died on the spot.

At this point, little Luke would pipe up, claiming that the odds of dealing 20 royal flushes in a row are so incredibly unlikely that his father must have cheated – and No-Eggs simply hadn't noticed.

At this point, Lucky Luke would say: Ah, my son, it might look to you as if I had cheated, but the whole point of this story is that if I had not dealt those 20 royal flushes, you would not be here to accuse me of cheating.  An alternative way of looking at it is that many a man (and perhaps lady) died at the hands of No-Eggs before I succeeded in dealing 20 royal flushes.  For all we know, No-Eggs, with his uncontrollable compulsion and amazing fortune in evading the law with regards to his card-related homicides, could have kept going until someone else dealt 20 royal flushes.  It's possible that someone else had already succeeded, and his son or daughter also accuses him (or her) of having cheated.  It's even possible that No-Eggs hadn't really challenged anyone before, that I was the first, and that I am merely phenomenally lucky, as my nickname suggests.  Either way, cheating or not, the result is that I survived my encounter with No-Eggs and I was thus able to meet your mother some years later.

It would appear, my son, that it is only because you are already so totally committed to the idea of my having cheated that you fixate on cheating as being the singular reason for my success in dealing the royal flushes.  But consider this:

The meeting between myself and your mother was unlikely.  There are millions of people in this country that we could have met up with, but it transpired that, one day, we just happened to be in the same place at the same time and we noticed each other and we liked what we saw and we had the time and inclination to act on that mutual attraction.  That attraction lead eventually to, ahem, shall we say "intimacy" and one sperm of the approximately 525 billion that a human male produces over a lifetime managed to make its way to one 400 (out of the 400 thousand potential) eggs produced by your mother over her lifetime – which necessitated, ahem, intimacy at precisely the right time for that particular sperm and that particular egg to meet.  Then environmental conditions had to be just right to switch on and off the genes that were needed to make you.  And this incredible good fortune stretches back over thousands of generations, hundreds of millions of generations in fact, if you include the species from which humans evolved.  So, Junior, you are an incredibly unlikely result, even if I may have cheated at cards.  Surely you aren't suggesting that these unlikely events wer all orchestrated merely so that you, "Cool Hand" Luke, would be born – or are you suggesting that we, your parents, somehow cheated to bring you about?

To this little Luke would reply that he doesn't really like the back story involving multiple attempts at dealing twenty royal flushes (although he would strenuously deny that this objection is largely due to the conflict with his preferred narrative), and that the disturbing discussion involving parental intimacy and sperm was even worse.  So, therefore, he would simply ignore it all.

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What the hell is all this about?  Good question!

Look here.  Now, admittedly, Barnes is talking about sitting down and dealing 20 royal flushes in a row, the likelihood of which is staggeringly unlikely.  Little Luke is indeed justified for thinking that his father probably cheated, it's the by far most likely option in the scenario as described – even if "No-Eggs" Oliver had had the time and inclination to challenge billions of people, rather than just millions.  But the point is that the fact that Luke Junior exists at all is evidence that 20 royal flushes were dealt – even if it is true that Luke Senior didn't cheat (and so long as Luke Senior didn't just create the story out of whole cloth).

However, in this scenario, cheating is most definitely an option.  Another option is magic, if we are inclined to distinguish that from more mundane forms of cheating such as palming or counting cards.

What would be interesting to know is, if we could somehow eliminate illusionist-like cheating (say that "Lucky" Luke's feat of dealing 20 royal flushes was recorded in high definition video from multiple angles and could be scrutinised by Penn and Teller and however many other professional illusionists that are thought to be necessary), would Barnes plump for magic as being the most likely explanation?

Because, after all, this is the real equivalent to the NID option that Barnes appears to favour.  (NID means "non-terrestrial intelligent design" for those who haven't followed the Carrier-Barnes squabbles over the past couple of years or so.)

A cosmologist who puts his money on magic?  Hm, now that is a guy I'd like to play poker with.

Fine-Tuning a Return to Sweet Probability

In A Return to Sweet Probability, I argued that the resurrection does not increase the likelihood of William Lane Craig's god, largely because the credibility that you give reports of the resurrection depends very heavily on your predisposition to believe that his god (or some very similar god) exists.

I want to do something similar with the fine-tuning argument.  I'll be using a variant of it implied by my old buddy, Luke Barnes (also referring to this earlier comment):

Let

o = intelligent observers exist

f = a finely tuned universe exists

b = background information.

NID = a non-terrestrial intelligent designer exists.

…

I can admit that “p(finely tuned universe | observers exist) = 1” and still conclude that

p(NID | f.o.b) >> p(~NID | f.o.b)

Now this argument between Richard Carrier and Luke Barnes was about Bayesian probability, so we know that:

P(NID | f & o & b) = P(NID & f & o & b) / P(f & o & b)

Holding f and o together (for reasons which should become apparent shortly) this eventually becomes:

If you want to see the working for this, look at A Return to Sweet Probability.

Now we need to define our terms.  I think it’s reasonably clear what the term o means, the intelligent observers in question are us.  By “intelligent”, we are not implying that the universe in question must be crammed with Albert Einsteins.  We merely need to be intelligent enough to observe the universe and note that the universe contains observers who are intelligent enough to observe their own existence.  Tick.

The term f is a little more contentious.  I’m going to use the definition that Carrier uses (see Part Deux), in part because it’s something that Barnes appears to have consistently overlooked:

If fine tuning is necessary for life, and there is no God, then necessarily life will only ever exist in correlation with fine-tuning. This is because all universes without fine tuning (sic) will thus by definition not contain life.

Note that this does not say anything about the hypothetical case in which there is a god.  A god may choose to fine tune the universe for life, or it may choose to magically create and sustain life even in universes which are not at all tuned for life, or it may choose to create a universe in which the range in which life is possible is very wide indeed.  Carrier appears to be conceding a point to apologists (such as Barnes) for the sake of the argument.  The fine-tuning argument will only work in a universe which is apparently fine-tuned for life, if there are observers in a hypothetical universe which is not fine-tuned for life then the fine-tuning argument fails (and, hypothetically, the pseudo-scientific, apologetic denizens of that universe will deploy the “non-fine-tuning argument” for whatever god they have imagined into existence).

So, in the instances in which there are observers, the universe will either be fine-tuned (either naturally or as the result of the intervention of a god) or non-fine-tuned (as the result of the invention of a god).  There is the possibility that some universes will be fine-tuned for life but, for some reason, life doesn’t manifest.  I don’t think we are particularly interested in those universes but in any event, those universes won’t have observers.  I think we can get around this scenario by strengthening the concept of fine-tuning – if a universe is sufficiently fine-tuned for intelligent life, then there will be, at some point, intelligent life.  Any tuned universe which doesn’t manifest intelligent life simply isn’t sufficiently tuned to consider it fine-tuned.  It certainly could be excluded from the set of universes that our universe fits into (also known as the reference class – that is: what is it about our universe that is pertinent to our consideration in this instance?  It would appear to be the fact that it contains not only life, but also intelligent observers).

So fine-tuning is defined as the sort of fine-tuning in our universe, that may or may not have been due to the intervention of a god, and resulted in intelligent life, life that was intelligent enough to observe that the universe is sufficiently fine-tuned to produce intelligent observers.

This is an extremely long and convoluted way to say what Carrier had been saying, P(o|f)=1 and, therefore, P(f&o)=P(f).  Or, in other words, once you have fine-tuning (as defined) you necessarily get observers, so the probability of fine-tuning and observers resolves down to the probability of fine-tuning.  This allows us to change all the (f&o) terms to f:

Perhaps you might want to weaken the definition of fine-tuning, but I don’t think that apologists want to.  If they do, I think they merely weaken their fine-tuning argument as a consequence but that can be an argument for another day if any apologist wishes to take that route.

We know that NID is the “non-terrestrial intelligent designer”.  I’m not as coy as some others, so I am just going to call this the god of people like William Lane Craig, Plantinga and (almost certainly) Barnes (but certainly many of Barnes’ adoring fans).  For the sake of the argument, let’s change NID to R as in “cReator” or “Representing god” or “what the apologists are Really arguing for”.

Fine-tuning (f) is, of course, the evidence in this argument, so let’s call it E.  If you are reluctant to roll o into f per the argument above, we could instead say that E=(f&o).

Then there’s our background, b (which we will capitalise and call B).  Background is a little vague in its definition.  What exactly constitutes background?  Fortunately, we can rely on Barnes again, who has written a piece on precisely this topic.

Background is everything we know, with the exception of the evidence that we are currently looking at, so in this case everything we know with the exception of fine-tuning (and thus observers).  However, this in effect resolves down to everything we know that is relevant.  I suspect that we have to be very careful about doing this step manually – because that which is relevant might not be immediately obvious and eliminating relevant data will skew the result.

I think we have enough to be getting on with.  We’ve renamed NID, b and f (or (f&o)) to R, B and E, respectively, so we have:

For anyone who has read A Return to Sweet Probability recently, this equation should be familiar.  On the right hand side of this equation we have four terms to consider:

P(E|R&B) – this is asking us: Given the hypothesis that there is a cReator, and our background information (everything we know, bar fine-tuning), what is the likelihood of our evidence (fine-tuning)?

P(R|B) – this is asking us: Given our background information (everything we know, bar fine-tuning), what is the likelihood of there being a cReator?

P(E|^R&B) – this is asking us: Given the hypothesis that there is not a cReator, and our background information (everything we know, bar fine-tuning), what is the likelihood of our evidence (fine-tuning)?

P(^R|B) – this is asking us: Given our background information (everything we know, bar fine-tuning), what is the likelihood of there not being a cReator?

On the left of the equation is P(R|B&E), which asks us: Given our evidence (fine-tuning) and our background information (which is, cumulatively, everything we know), what is the likelihood of a cReator?

The value of this equation relies very heavily on two questions having already been answered, namely the likelihoods of there being a cReator and not being a cReator, given what we know, apart from fine-tuning.  It also relies, rather heavily, on the assumption that fine-tuning doesn’t follow necessarily from what we already know.  If we were, in the future, to discover that B→E (if B then (necessarily) E), then B&E would equal B, so the left had side of the equation would become P(R|B).  This would naturally follow because P(E|R&B) = P(E|^R&B) = 1 and P(R|B)+P(^R|B)=1.

Therefore, there is an assumption that fine-tuning is consistent with our background (everything we know, bar fine-tuning) but our background is insufficient.

Now, we should make clear something about “background”.  Barnes’ says, of background, “tell me everything” and warns that information should not be arbitrarily ignored.  So, my question is this: is it arbitrary, given that no time related caveat is placed on the cReator hypothesis, to limit “background” to that which we know now?  How extensive is this “everything” of which you speak?  Is it possible that, in the future, we will discover that the fine-tuning we observe is a necessary consequence of relatively simple, yet entirely natural laws?  It would seem that the answer to that question, according to an apologist, should lie somewhere between “maybe” and “I don’t know” – perhaps somewhat closer to “maybe” given that “I don’t know” is saying that it isn’t necessarily impossible, and is therefore possible, making the answer an unambiguous “yes, it is possible”.

So, it seems to be unreasonable to assume that our background is always going to be insufficient to explain fine-tuning.  The assumption might be valid if we presupposed an interventionist god, or if there is some natural limit on the information that we can glean about the universe.  In the case of the latter, the argument by apologists is unacceptably stacked in favour of their god (assuming the existence of god, what is the likelihood of god?)  In the case of the latter, such a limit would imply that the question of the existence of a god may never be resolved, a god may never be proved but it may also never be disproved.

This is, I guess, a wonderful conclusion for apologists.  Potential job security until the end of time!

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I think that I am now ready to assign tentative probabilities to each of the terms in the equation.  I’m going to be as charitable as I can to the apologetic cause.

P(E|R&B) – we don’t know

P(R|B) – we don’t know

P(E|^R&B) – we don’t know

P(^R|B) – we don’t know

Plugging those values in, we arrive at P(R|B&E) = P(R|B) = we don’t know.

So, we could argue endlessly about how to manipulate the identities in the Bayesian calculations, and how likely or unlikely fine-tuning itself is, but at the end of the day, we merely arrive at “we don’t know”.  Sure, an apologist may immediately transmute that “we don’t know” into “god exists” via the subtle alchemy of an appeal to ignorance.  The more intellectually honest among us, however, are left with a mystery to investigate – why does the universe appear to be fine-tuned? – without any real need to worry about the superstitious wretches who continue to dog our investigative heels.

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It’s vaguely possible that someone is going to be upset that there were no jellybeans in this article.  I’m sorry, but the probabilities are so nebulous that I didn’t see any point in assigning any, even tentatively.

If someone else is keen to do an analysis using the jellybean model, feel free.

Luke Barnes (Probably) Uncloaks Even More

It's not every day that you see a cosmologist unload on a historian with "righteous" indignation, but that is what has been happening over at Letters to Nature (initially in January but also stretching into February).  What a fuss about Bayesian probability! – I wonder, what was the likelihood of that?

I see this as further evidence that Barnes is (probably) uncloaking some more because he has drawn attention to the fact that, two years ago, he was arguing with Richard Carrier for an argument in favour of NID, or "non-terrestrial intelligent design".  He didn't do this unknowingly.  Here's an extract from one of his comments:

One more question. I won’t make any claims. I’ll even make it multiple choice. Just give me your main argument against fine-tuning in probability notation.

Let

o = intelligent observers exist

f = a finely tuned universe exists

b = background information.

NID = a non-terrestrial intelligent designer exists.

Here’s the question.

1. In probability notation, what follows about the posterior probability of NID from the fact that p(f | o) = 1?

Multiple choice:

a) p(NID | f.o.b) / p(~NID | f.o.b) = 1

b) p(NID | f.o.b) / p(~NID | f.o.b) = p(NID | b) / p(~NID | b)
(Does this follow from footnote 29?)

c) p(NID | f.o.b) / p(~NID | f.o.b) = p(NID | o.b) / p(~NID | o.b)
(if o is part of b, is this option equivalent to the previous one?)

d) p(NID | f.o.b) / p(~NID | f.o.b) is independent of p(o | ~NID) – the probability that a life permitting universe would exist by chance. Thus, even if p(o | ~NID) << 1, this fact is irrelevant to the posterior probability of NID.

e) Some of the above. Please specify.

f) None of the above. Please answer in probability notation.

So, he (Barnes) is fully cognisant of the fact that his fine-tuning argument is essentially an intelligent design argument.

It's interesting that he should be so keen to faff around with Bayesian probability when his speciality is apparently star formation (or some such).  These sorts of arguments have primarily been the preserve of philosophers, and quite often apologists (and, as a consequence, anti-apologists).

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On the topic of Barnes' faffing about with Bayes, he wrote a piece called 10 Nice things about Bayes' Theorem.  I too have dabbled in Bayes' Theorem, primarily because of WLC's abuse of it, which means that it relates to the resurrection thing, rather than the fine-tuning thing.

Barnes had a go at Carrier, in a comment from two years ago, in which he wrote:

* “all prior probabilities are the posterior probabilities of previous equations”.

Learn to use probability terminology correctly, please. Don’t talk about the probability of an equation.

Interestingly, in his 10 nice things piece, Barnes wrote:

Today’s posterior becomes tomorrow’s prior. Hence, Bayesian updating.

This is basically exactly what Carrier was saying, although in the eyes of a hostile witness, he was apparently talking about Pr(equation) rather than the probability that falls out of an equation like Pr(A|B)=Pr(B|A).Pr(A)/P(B) – the probability associated with that equation, perhaps, if not "of" as in common parlance.

Strange.

Perhaps Barnes just doesn't like to call Pr(A|B)=Pr(B|A).Pr(A)/P(B) an equation which is still strange, because it acts precisely like an equation, with multiplication and division, and in some cases there are additions and subtractions in Bayesian calculations – just like in real equations.  Still, it does sound like he was grasping desperately at straws.

I wasn't that keen to slog through Barnes' most recent attacks on Carrier, but after noting this little own-goal on his part, I'm now a little more intrigued.

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Note that Carrier has since replied, here.

On Flew and Ehrman

While investigating William Lane Craig I came across two people whose names were not previously well known to me – Bart Ehrman and Antony Flew.  I had a bit of a closer look at them and found them to be interesting cases because they both moved on the atheist-theist spectrum as illustrated below, but in different directions.

This spectrum illustrates a range of possible positions between “strong atheism” on the top and “literal fundamentalism” on the bottom.  I might not have accurately captured all of them.  It should be noted that as you get closer to the bottom, you approach a specific God and in the context of this discussion we can assume that this is a Christian God.  As you approach the more fundamentalist position, evidence disappears as a factor.  I don’t mean that evidence itself disappears, but rather that evidence is looked at differently by people with these positions – evidence becomes something that needs to be explained, rather than being an essential element of an explanation.  (See my article on evidence.)

For ease of reference, we can consider this spectrum in light of a nine-point scale:

These are my own descriptive terms.  None of them are intended to be pejorative, with the possible exception of “Agnostic Fence Sitting”.  This category is for those who want to apply Pascal’s wager but, despite trying their best to believe in a God so as to not be punished eternally for failing to do so, are still not able to really truly believe due to the lack of evidence.  In other words: “there’s not really any evidence, but I’ll lean towards the God premise just in case”.

Let’s compare the history of Ehrman and Flew.

These are based on rough estimates.  Bart Ehrman’s crisis of faith that cured him of fundamentalism happened in the mid-1980s and was followed by about 15 years of liberal Christianity.  Flew was tending towards a deistic belief, or a belief in an “Aristotelian god” or a First Cause, in his mid-70s as early as 2001.

In 2007, There is no A God was published by Harper One under Flew’s name, even though the book was largely written by the “co-author” Roy Varghese and “copy edited” by Bob Hostetler.  Flew’s contribution seems to have amounted to granting approval and allowing earlier work to be incorporated in the book.

Note that Flew’s regular publisher was Prometheus Books, whose publishing goal is described as addressing “the educational, scientific, professional, library, popular, and consumer markets”.  Prometheus does have a few books on the topic of religion, but a brief look at the titles indicates that they have a skeptical orientation, in line with the founder’s intent (Paul Kurtz also founded the Committee for Skeptical Inquiry, an organisation of which Flew was a fellow).  Harper One’s area of publishing interest is described as “the full spectrum of religion, spirituality, and personal growth”.  It doesn’t take much skepticism to think that perhaps Harper One was selected as the publisher because Prometheus would not have been able to provide editors who would be as “accommodating”.  

I am perhaps being a bit unfair in labelling Ehrman as a weak atheist.  It is true that Ehrman explicitly denies being an atheist, is antagonistic to New Atheists and claims to be an agnostic.  However, when speaking to Justin Brierly on Premier Radio’s Unbelievable program, Ehrman described his position in terms that correlate with weak atheism.  Ehrman is certainly not a strong atheist but, given that his position is sufficiently similar to mine, I feel justified in asserting that he is a weak atheist.

(Update 30 March 2023: in his discussion with Sam Harris on Making Sense, Ehrman said "I'm an atheist too", indicating that his position is similar to that of Harris.  That might indicate that he is now at the stronger end of weak atheism.)

The question of whether Ehrman is an atheist (of any type) or not is related to another sort of question: where exactly is the line between “atheists” and “others” and the line between “Christians” and “others”?

I would have thought that for a Christian, the line depends on the nature of their belief.  If a Christian is a fundamentalist, then a wishy-washy type who is willing to interpret the Bible (and is not born again) is not a proper believer.  For an atheist, someone who thinks “there is probably something out there” is suffering from precisely the same type of delusion as the fundamentalist; just not to the same extent (we could call this “Deluded Lite”).

The moves that Flew and Ehrman made on the spectrum are, I believe, as illustrated below:

Now, on this diagram, it looks like Ehrman has undergone a significantly greater change, but there is no real scale involved.  To get a better understanding of the major changes of position, we perhaps should look at them differently.

So, in other words, Erhman went from someone who believed it all, to someone who reckoned that there is sufficient evidence to support the assertion that there was a human known as Jesus, but not much else.  Despite this, I’m reluctant to count him as a true opponent to William Lane Craig in a debate because he seems to shy away from the most likely explanation for a story as amazing as that of Jesus in the almost total absence of any supporting evidence outside the Bible.  That it is fiction.

Flew, on the other hand, went from someone who didn’t believe a thing to someone who was willing to credit God with creating the universe, but not much else.  Despite this, there are plenty of people willing to claim that Flew’s conversion is a great victory for theism (even though he specifically did not convert to theism).  Why is this?

Well, let’s look at a few interesting facts.

Biola University is not known for being a deist university.

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Now I have previously stated that I don’t really count Ehrman as being a true “opponent” to William Lane Craig.  This also means that I don’t count Ehrman as a “convert” to atheism, even though his position is almost completely consistent with my atheism.

A small part of my reasoning relates to the fact that Ehrman remains a New Testament scholar, who believes there actually was a Jesus and who seems ambivalent about the Bible.  However, the vast majority of my reasoning relates to the single fact that it does not matter who Ehrman was before losing God, or indeed after.  My personal lack of belief is neither strengthened by a conversion of a theist to agnosticism nor weakened by the conversion of an atheist to deism.  The pope could convert to atheism, and it’d make no difference.  Richard Dawkins could come out as a closet fundamentalist, and it’d make no difference.  My atheism is an entirely personal lack of belief on my part.

Now that that is out of the way, I want to state that I am appalled by the way some people treated Flew.  It is very sad to watch footage of a man who was clearly showing signs of mental deterioration, evident as early as 1998 during the debate with Craig at Biola University, as he is paraded around by smug theists.  (Remember footage of tired and confused allied soldiers making televised announcements on behalf of Saddam Hussein?  It’s rather similar, except Flew was never returned.)

There is a notorious interview between Lee Strobel and Flew in which Strobel shamelessly, and relentlessly attempts to put words in Flew’s mouth (when the interview was held is unclear but the first reference on the internet that I could find is dated November 2006).  Of particular interest in this interview is that not only does Flew appear to be not at his best, but he also clearly states twice that he is not going to write a book and implies it a third time.  Flew does not mention having just written a book (There is no A God was already mentioned as being circulated in pre-print as early as September 2006).
 

·         4’:39” onwards

o   Flew: “I haven’t even begun to think about this book that I am certainly not going to attempt to write”

o   Strobel (jocular): “We’re going to get you to write it”

o   Flew: “Oh no you’re not”

·         5’:11”

o   Flew: “I’m not going to write the book”

·         9’:05” onwards

o   Flew: “Well, I think, ah, if we were involved in a discussion for this book, that would have to be considered, yes.  I think it’s a reasonable thing for someone to argue.  It doesn’t mean it’s the right, but it’s certainly right for someone to say that, that”

o   Strobel: (incomprehensible vocalisation but probably) “Yeah”

o   Flew: “Yeah and I think that that is in fact what theists would want to say in some way, wouldn’t it, the whole purpose of this creation was to produce believers.”

I strongly recommend that people listen to at least two debates, one between Flew and William Lane Craig from 1998 and a more recent one between Ehrman and Craig.  Compare the clarity of thought exhibited by Flew and Ehrman and just ponder whether the likes of Craig and Strobel should be fisting the air and claiming victory for the Lord because Flew became a deist.

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One last thing … I’ve tried, but I’ve not been able to find any reference to claims by high profile atheists that Ehrman becoming an agnostic should be considered as some sort of victory for atheism.  For anyone trying to prove me wrong, I’d happily accept something said by Dawkins (and any who post articles at the Dawkins Foundation site), Dennett, Harris, Hitchens, Smith, Krauss, Law and Shermer.  The clarity of the statement should approach the title of Gary Habermas’ article (Atheist Becomes Theist – Exclusive Interview with Former Atheist Antony Flew) or that of the book crafted by Roy Varghese (There is no A God: How the World's Most Notorious Atheist Changed His Mind).

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This article blends information freely available from Wikipedia, Richard Carrier’s blog, Mark Oppenheimer’s NY Times article, and audio and video of debates involving Strobel, Craig, Flew and Ehrman.  My thanks to the people who made this information available.