Fifty Fifty?
One question we keep hearing a lot in relation to this discussion of religion is one along the lines of ‘Why bother?’ Why bother to argue about religion, or to analyze it, or to point out weak arguments some of its defenders use? What is the point? Religion is a need, it’s always been there, it’s probably hard-wired, people aren’t going to give it up, arguments are beside the point, you’re wasting your time. Well, one, I’m not entirely sure that’s true. Not in all places and all times, and if not there and then, then not in general either. That is, I think there may be a confusion between what is hard-wired and what is simply heavily reinforced by the surrounding culture. There have been people, cultures, areas, that were more or less secular, more or less skeptical, more or less unsupernatural. Surely if that has happened in some situations, it can happen in other situations. It may or may not be desirable, but I think whether it’s possible or not is an open question. And two, and more to the point, even if that is true, obviously it’s not universally true. Obviously some people do not feel a profound unappeasable need for a deity. Some people (I’m one) even feel an active repugnance for the idea.
That being the case – surely there must be vast grey areas in between. Between ardent believers who wouldn’t change their minds no matter what anyone said, and determined skeptics who ditto. Surely there are plenty of people who believe, but tentatively; who believe, but are open to argument; who believe, but recognize the difference between belief and certainty. And plenty more people, especially young people, who just don’t know.
It’s not as if people never do change their minds about anything, after all. They do. We do. I do it myself all the time, and I don’t think I’m so peculiar that I’m the only person on the planet who does. Often the mind-changing we do is fairly easy, because it meets no reisistance: it’s not a matter of altering engrained habits of thought or entrenched intellectual commitments, but simply a matter of learning something we didn’t know before, or learning more on a subject about which we knew little. But now and then, if presented with powerful arguments or evidence, or if we are at some kind of mental turning point, we can even change our minds about things that really matter to us.
And it is worth chivvying away at all this, I think, because bad arguments go on being made. It is worth pointing them out, in hopes that their perpetrators will at least manage to come up with better ones. There is for instance this one which a reader sent me a link to. Read that article and then wonder if the ‘scientist’ (why does the article never say what kind of ‘scientist’ the guy is? what is the point of that absurd honorific use of the word ‘scientist’ in such a totemistic way? that’s the kind of thing that puts people off the very word. And what’s with the repetition of the ‘Dr’ bit? What, he has a PhD therefore what he says can’t really be as silly as it sounds? Is that the idea? Well, I hate to tell you, but…) would have started from such a bizarre assumption if he hadn’t been setting out to find what he wanted to find in the first place.
A scientist has calculated that there is a 67% chance that God exists. Dr Stephen Unwin has used a 200-year-old formula to calculate the probability of the existence of an omnipotent being. Bayes’ Theory is usually used to work out the likelihood of events, such as nuclear power failure, by balancing the various factors that could affect a situation. The Manchester University graduate, who now works as a risk assessor in Ohio, said the theory starts from the assumption that God has a 50/50 chance of existing, and then factors in the evidence both for and against the notion of a higher being.
Oh is that the assumption it starts from. Ah. Can we use that for everything? For anything? Shall we all become Bayesians and see how it works? Let’s see. Zeus has a 50/50 chance of existing. So does Tinkerbell. So does Francis the Talking Mule, and Krishna, and Spider Man, and the crew of the Enterprise, and the dramatis personae of ‘The Tempest,’ and the characters in Middlemarch. Everything we can think of has a 50/50 chance of existing, and so does everything we can’t think of. That should cover it.
‘Assumption’ is a very interesting word. It makes a large difference which ones we start from, and why. And it goes on being worth pointing that out, I think.
Update: here is an excellent comment on the book, recommended by José.
Oh, that silly book…The guy is a mathematician. What I’ve read about this ‘solid piece of scholarship’ : coherent statistics but wrong and arbitrary premises. Sadly, stupidity affects scientists too.
This review at Secular Blasphemy hits the nail on the head:
http://blogs.salon.com/0001561/2004/02/28.html#a4715
“The Manchester University graduate, who now works as a risk assessor in Ohio…”
It is positively scary that this person is working as a risk assessor. Yikes.
The Bayesian formula works by starting with estimates of probability for various propositions, and then mathematically refining them. I discuss it a bit in my article on Occam’s Razor in the current issue of Skeptic. It can be a very useful tool for assessing the merit of rival theories when used properly.
But it’s quite often used improperly, and it’s obviously limited by the validity of our starting probability assignments. Lacking rigorous application, it becomes a very complicated tautology, which simply appears to strengthen faulty starting assumptions and lend them a veneer of respectability. That’s certainly the case here.
Phil
Thanks for the link, José.
“limited by the validity of our starting probability assignments”
That’s certainly how it struck me. 50/50 indeed! On what basis?!
Yeah, let’s hope he’s not assessing any risks we might have to take, eh.
There are people that think Plantinga’s modal logic ontological argument is convincing – this is at least an improvement on that – I think at this rate Theists are going to keep revising their probabilities down until they cling to the idea that it may even be -possible- that God exists, no matter how small the p value…
I thought the most striking aspect of the article was that the existence of goodness was taken as evidence for the existence of a deity, again assuming that morality is only meaningful in a theological context (and a christian theology at that; hardly applicable to all religions). With sophistry like that you could prove anything…
That guy could make a fortune on roulette. All he has to do is always put his money on 17 (say). After all there is a 50/50 chance of the ball landing on 17 and also of the ball not landing on 17; yet those stupid casinos insist on paying out odds of 36:1.
Come to think of it; why stop at roulette! He should be playing the national lottery every week. The payouts are even bigger, but the odds are the same, 50% chance of not winning, and 50% chance of winning.
The full article is even more painful to read than the extract provided in B&C. i felt myself getting stupider as i red it.
[great snort of laughter]
Yeah I no wut yu meen, kriss. Mee 2.
“the existence of goodness was taken as evidence for the existence of a deity”
I know – how absurd is that? Some 70 objections leap to mind in a fraction of a second.
“You don’t need to limit yourself to proving the potential existence of fictional characters, you can provide arbitrary probabilities for anything you like”
I know, that’s why I added the part about what we can’t think of. Just anything and everything at all – 50/50, right down the line. There’s a good knock-down argument for you!
I find it funny that all of you can so easily dismiss the book and the author without hesitation after reading one small article.
You may be right but your arrogance and snide comments don’t speak of intelligence or an open mind. The book uses probaility as a way to discuss faith not as some sort of mathematical proof that God exists. The author has a PhD in quantum physics does that count as a scientist?
Not really that funny. If the small bit that has been discussed is so wrong (which it is), why the hell would we want to waste more time by reading the rest. Your accusations of snide comments and arrogance don’t really deal with issue – the worth or otherwise of the book. (FWIW snideness and arrogance are often found in people of intelligence). We are not discussing our character failings, but the books failings (that it exists in particular). There is nothing wrong with throwing scorn and ridicule on the scornworthy and ridiculous. This book is both.
Oh well I never make any claim not to be arrogant. Woudn’t dream of it.
But the claim about the 50/50 chance is well worth criticising whether it’s made by the book or by the review. It’s inane, whoever made it.
What makes a PhD in quantum physics (and now loss adjustor) sufficiently expert in such metaphysical speculation to be able to put a 50% probability on the existence of God? What about a Professor of Quantum Physics – would they be the ultimate expert on the issue? How about a nobel prize winner in quantum physics, would they be like the pope?
I’m rather seriously distressed by the amount of ignorant hostility in this comments set. At the risk of sounding hostile myself, I don’t think that many of you are qualified to discuss Bayesian statistics — if you are, it doesn’t come through.
A central feature of Bayesian statistics is the notion of probability refinement; from an initial (and almost certainly wrong) guess about a probability, we refine the guess *based on the evidence to hand*. So, yes, it’s quite reasonable to take as a starting point a 50/50 shot of God, or the Easter Bunny,
Spider-man, Attila the Hun, or my left ear, existing IF YOU DON’T KNOW BETTER. 50/50 is, in fact, one of the best starting points to use precisely because it’s so uninformative. If you think you have reasons that the probability should be different — well, that’s all just grist for the Bayesian mill. Present your evidence and the final answer will be different from 50/50, to exactly the extent that your information actually sheds light on the subject.
Let me then ask two questions. IF there were a God (as described in the Christian scriptures, handwave, handwave), what would be the probability of “goodness” also existing? I think it’s fairly clear that then answer should be 100% — the Bible is fairly clear about goodness being part of the world, and so under the working assumption that the Bible is true, so is the existence of goodness. Conversely, if we assume the non-existence of God (handwave, handwave), what’s the probability of “goodness” existing? If it’s anything less than 100%, then the fadct that goodness appears to be a part of our world is indeed evidence — not proof, but definite evidence — of God’s existence.
That’s where this whole mess falls down. In order to make the Bayesian stats work out properly, I need to come up with exact probabilities for the chance of goodness existing in the absence of God, and unlike the first one, these don’t get tuned as I refine the numbers. So I
can plug in any assumption I like for the second number and get any corresponding answer.
You can disagree with Unwin’s findings — I do myself. But at least understand what you’re disagreeing with. His methodology is fine, and he’s applying it to a whole bunch of “evidence” he has no way of evaluating. Don’t argue with his starting point — argue with the path he uses to get from there to his conclusion.
Sheeesh.
Hmm, not sure I follow you.
“from an initial (and almost certainly wrong) guess about a probability, we refine the guess *based on the evidence to hand*. So, yes, it’s quite reasonable to take as a starting point a 50/50 shot of God, or the Easter Bunny,
Spider-man, Attila the Hun, or my left ear, existing IF YOU DON’T KNOW BETTER.”
I don’t see it. Why is it reasonable to take a 50/50 shot as a starting point? Depending on what you mean by ‘know better,’ of course. Are you taking ‘if you don’t know better’ to mean a complete blank, no idea, no opinion, no evidence, nothing at all? Starting from zero? But who is in such a situation with respect to either God or the Easter bunny? Or do you mean something else by ‘if you don’t know better’?
“I think it’s fairly clear that then answer should be 100% — the Bible is fairly clear about goodness being part of the world”
What? I really have no idea what you mean here. What is ‘goodness’ and why does it prove anything about a deity? But then I don’t know what you mean by handwave, either.
You’re certainly right about my non-qualification to talk about Bayesian statistics. But all the same, I don’t follow you.
Yes, “if you don’t know better” in this context means an absolute complete blank, no idea, tabula rasa, pick your own metaphor for utter and complete ignorance. And while I’m sure we all have opinions on the matter of whether or not God –or Spider-man — exists, in the absence of evidence, the opinions don’t amount to a half-cup of warm spit.
Bayesian statistics are simply a method of evaluating and balancing the evidence. In the case under discussion, we’ve got two competing hypotheses; one, that the God described in the Bible exists (as described, if that’s not redundant), and two, that He doesn’t. In the absence of evidence, why make a biased assumption?
That’s all the starting point is — an unbiased and uninformative assumption, but one that is mathematically necesary to allow the mathematics to work. Bayes’ theorem gives us a way to change an existing prior probability to be more in line with observed data; it does not allow us to create probabilities out of nothing. But any starting prior probability can eventually be tuned to be (very close to) the correct one given enough evidence.
If you have reason to prefer a different hypothesis,… well, that’s how Bayesian statistics work, by adjusting the starting probability to account for evidence received. Stripped of the math, the idea is simply that we evaluate the predictions a given hypothesis would make — and then grade the hypothesis according to whether it makes correct predictions (which makes it more likely) or not. So let’s look at the “goodness” issue for a moment. Taking the view, for argument’s sake, that the Bible is correct, it is immediate from Genesis
that “goodness” is a part of this world.
(Genesis 1:31, “God saw everything which he had made and it was very good.”)
Thus, under our working hypothesis, if God exists, the probability of goodness being part of the world is 100%. Of course, you’re not compelled to accept that hypothesis as anything other than a working assumption, and you are welcome to work out your own probability for “goodness” being part of the world based on the working assumption that God does not exist. (And THIS is where the researcher went off the rails, since any such probability is highly likely to be plucked out of thin air.)
That’s what “goodness” has to do with a deity — the deity itself says that if He exists, goodness also exists. Does the hypothesis that the deity exist make
a correct prediction? Bad reasoners, for centuries, have been trying to say — “well, since goodness exists, He must also exist.” This, of course, is the fallacy of Affirming the Consequent. But Bayes’ theorem provides a legitimate method of “affirming the consequent” based on probability theory.
The danger is that I can do the same trick in the other direction. The same Genesis quote argues that the chance of evil existing in the world is 0% (since
“everything” He made is good.). We can apply the same math to our revised prediction and come up with a probability of God existing based on our
evidence from both good and evil. The math doesn’t care — it’s just accountancy with probability.
The key is in the probability assessment for the various pieces of evidence. *IF* God exists, what’s the probability that Britney Spears would? *IF* God didn’t exist, what’s the probability that Britney Spears would? If you can come up with a well-founded argument for why those two probabilities should differ, then we can develop deep theological conclusions from pop tarts. Otherwise it just turns into an issue in
“garbage in, garbage out.” The problem isn’t with the math — it’s with the way evidence is assessed. The math works. The logic is sound. The problem is with the assessment of the evidence withing the framework.
“The math works. The logic is sound.”
I’m not disputing that, I’m only disputing the starting point.
“In the absence of evidence, why make a biased assumption?”
I flatly disagree that there’s no evidence on which to base an opinion that the god of the bible is a literary character rather than something that exists in the world. So apparently we’re just talking past each other.