When I decided to restart this student freethought group at UF, I asked our faculty advisor, Prof. of Philosophy Gene Witmer, whose books I should get if I really wanted to read the strongest arguments that theism had to offer. His suggestion?
Richard Swinburne, Oxford philosophy professor, prolific author of serious works of theistic apologetics (e.g., The Existence of God, Is There a God?, Providence and the Problem of Evil)...who has apparently lost his marbles.
He claims in The Resurrection of God Incarnate to have mathematically calculated the likelihood of Jesus' resurrection, using Bayesian probability, at 97%. His logic [lack thereof]?
Richard Swinburne, Oxford philosophy professor, prolific author of serious works of theistic apologetics (e.g., The Existence of God, Is There a God?, Providence and the Problem of Evil)...who has apparently lost his marbles.
He claims in The Resurrection of God Incarnate to have mathematically calculated the likelihood of Jesus' resurrection, using Bayesian probability, at 97%. His logic [lack thereof]?
- The probably of God's existence is one in two. That is, God either exists or doesn't.
- The probability that God became incarnate, that is embodied in human form, is also one in two.
- The evidence for God's existence is an argument for the resurrection.
- The chance of Christ's resurrection not being reported by the gospels has a probability of one in 10.
- Considering all these factors together, there is a one in 1,000 chance that the resurrection is not true.
oy vey!
Mark Chu-Carroll has an analysis, if one is even deserved for this kind of madness, which can be summarized thusly:
By a similar argument, I can say that probability of pink winged monkeys flying out of my butt is one in two: that is, either they will fly out of my butt, or they won't. The probability that those monkeys will fly to the home of this Oxford professor and pelt it with their feces is one in two. If pink winged monkeys fly out of my butt, that's an argument for the likelyhood of a fecal attack on his home by flying pink monkeys.
Do I really need to continue this? I don't think so; I'd better go stock up on monkey food in my bathroom.
On another note of sadness, five Mexican children were killed as they prayed at a cross by lightning. Why should we believe there was a God on the other end of those prayers, again? Oh wait, I remember now, everything God does is good, including allowing five children, ages 9-16, to be killed by lightning while offering up prayers and thanksgiving to God. What was I thinking? I'd better go pray for forgiveness...at a plastic cross, of course.
1- That would only be the probability for any god at all. The probability of the Christian God in particular would be one in however many gods and goddesses people have thought up. Or could think up. It could be one in infinity. Also, just because there are only two choices doesn't mean both choices are equally likely. I can only be sick or well but my probability of being sick at any given time is not always going to be 1 in 2. It will vary depending on my exposure to germs, the state of my immune system including stress levels and other factors.
ReplyDelete2- Same fallacy - two choices are not equally likely. Besides, doesn't that depend on which god we're talking about? Some gods by definition cannot become embodied in human form.
3- This does not follow. Again, no evidence has been presented for this particular God. Not all gods have resurrections.
4- Why one in ten? And how can anyone know this given that some of the gospels may be missing? The Book of Mark in particular has an awkward ending and is believed by some scholars to be incomplete. He's trying to calculate a probability that can't be calculated.
5- Considering all these factors together, if this is the best that theism has to offer we ought to just save time by declaring all atheists the automatic winners in any religious debate.
But seriously, though, if you want to read the works of an intelligent Christian, try Bishop John Shelby Spong. He's not your typical Christian, though, that's for sure. Check out: http://www.dioceseofnewark.org/jsspong/ and http://www.geocities.com/reuther_2000/spong.html.
--Lynne
I actually know of Spong. Orthodox/Conservative Xians detest him.
ReplyDeleteHis admission that liberal scholarship is powerful and critical analysis of the Bible yields no grounding for orthodoxy undermines their [conservatives'] power and influence. Of course they hate him.
I'm afraid this bashing of Swinburne isn't really fair. Your summary of his reasoning is taken from a brief CNN article on the same -- hardly the most reliable source for philosophical argumentation. I've not read Swinburne's book on the resurrection, but I can assure you that there's no chance in hell that Swinburne is so foolish as to think that he can get from "either P is true or P is false" to the conclusion that "the chance that P is true is ½ and the chance that it is false is ½".
ReplyDeleteIf you look at the review of Swinburne's book to which you yourself linked, you'll see that Swinburne uses all sorts of other arguments to arrive at these probabilities. These other arguments may be flawed in several ways, but they're simply not fairly compared to parodies of the sort Chu-Carroll provides.
Most crucially, Swinburne is relying on other work he's done in which (he thinks) he's provided good reasons for thinking that there's a decent -- at least 50% -- chance that God exists in the first place. His project in the book on the resurrection is to build off that other work. Once you see this, then the sort of thing he's trying to do is not so obviously crazy. Suppose you've already convinced yourself that there's at least a 50% chance God exists --where you understand "God" in a relatively specific way to include several attributes such as being all-loving, personal, and so on. Given those attributes, you can make reasonable estimates of how likely it is that -- if this God exists -- he would do various things, including the act of becoming incarnate and being resurrected and so on.
These are all conditional probabilities, of course: given that this sort of God exists, the chances that he would do these things is such and such. If you then buy the claims that Swinburne makes -- on grounds set out in other books arguing for God's existence -- about the probability of God existing, then you can go ahead and figure the overall probability of the resurrection. That's what he's up to. He hasn't lost his marbles at all.
Of course, I don't mean to say that I agree with him on any of this. I think his initial probabilities regarding God's very existence are entirely off, as I think his estimation of the power of arguments for God's existence is in error. But he's hardly irrational.
Prof. Witmer,
ReplyDeleteI agree that from reading Swinburne, the man certainly isn't irrational. I agree that the presentation of the arguments may be unfair, in the way they were distilled by the reporter.
However, I read the review of the book, and I find such passages troubling as this one:
From this Swinburne concludes that the probability that God will become incarnate, if he exists, is 1/2: “Again, so as not to exaggerate my case, let me suggest that these reasons make it as probable as not that, if there is a God, he will become incarnate . . . .” (p. 50). These reasons are not given merely to incline the reader to Swinburne’s conclusion, but also play a crucial role in his argument; they determine both the prior probability that God will become incarnate as well as what we would expect if God does become incarnate, both of which are important in Swinburne’s use of Bayes’ theorem.
However, I found it difficult to see why these reasons make it as likely as not that God would become incarnate if he exists. Swinburne himself discusses a couple of plausible alternatives to becoming incarnate as the best act for God to do, and readers may think of several more. He endorses a form of the principle of indifference applied to God’s actions, and thus one would expect Swinburne to conclude that the probability of God becoming incarnate (given that he exists) is about 1/n, where n is the number of equally best acts that God could do (p. 34). Given this, it is difficult to see why Swinburne concludes the probability of God becoming incarnate, if he exists, is 1/2 instead of 1/3, and many readers will assign an even lower probability.
I couldn't say it any better myself. Simply put: why does n = 2?
Also:
“Let me not exaggerate my case and suggest (despite my strong feeling that this value should be higher) that we give it a fairly low value and put it provisionally at 1/10 ....” (p. 212).
For instance, what % probability, based solely on the Problem of Evil, would you assign to God's existence? 33%? 10%? 5%? 1%? How could we even hope to substantiate the assignment of discrete numerical probabilities to these concepts and arguments?
It also may be that if I read through the justification [in the book itself], there would be some rational and straightforward way to attach Bayesian formality to questions of philosophical interest. As it is, however, I do not have the book; in spite of, and partly due to, the supplied passages, I cannot comprehend how such a task could be accomplished. As a scientist who works with numbers fairly regularly, I cannot quite comprehend the ease with which Swinburne takes his assignment of numerical values as legit. He would have to lay out a formal system for assigning probability using either fuzzy logic or something, which our reviewer doesn't hint at.
In fact, our reviewer says:
Swinburne claims his probabilities are to be viewed as epistemic or logical probabilities. According to Swinburne, it is a logical truth, necessarily true or necessarily false, that some evidence makes a certain proposition likely to some degree. Although it is controversial whether an adequate account of epistemic or logical probability can be developed, there must be some clear connection between rational belief and any account of epistemic or logical probability in order for the concept to be of any use.
...throughout this book it was difficult to see why it would be irrational for someone to disagree with Swinburne on the probabilities he assigns, and to have different degrees of rational belief. Many philosophers may think it rational to withhold judgment on some of the probabilities Swinburne discusses, which allows as rational more degrees of belief than Swinburne does.
...Swinburne’s discussion of a wider range of evidence and Bayes’ theorem does not solve these problems, but instead focuses the debate on the values of other probabilities. Since Swinburne is not successful in defending the values he assigns to various probability statements he used in Bayes’ theorem, I do not think he is successful in showing that, given our evidence, necessarily it is very likely that Jesus was God incarnate who rose from the dead; rationality appears to tolerate a wider range of belief than Swinburne acknowledges.
It seems that this very paragraph hits at Mark Chu-Carroll's treatment, and no one denies that:
According to Swinburne, it is a logical truth, necessarily true or necessarily false, that some evidence makes a certain proposition likely to some degree.
...but "likely to some degree" appears to be the Achilles heel, doesn't it?
I certainly did not understand why such an intelligent fellow would pose such a silly system for "probabilizing" God's existence. His numbers are no stronger or weaker than the arguments themselves, and do nothing to strengthen or weaken the premises therein. I just don't get it -- he lays out the case quite nicely elsewhere without resorting to...what seems...an attempt at making quantifiable concepts which do not reduce to discrete values.
I am philosophically ignorant, so can you say that you've encountered other arguments where the author/speaker ends with a "guesstimation" of the strength of his argument by converting its probability to Bayesian formal math?
P(c/f&k) = P(f/c&k)P(c/k) ÷ [P(f/c&k)P(c/k) + P(f/~c&k)P(~c/k)]
If Swinburne lays out a formalization of fuzzy logic, or something similar that would work, I could buy into writing his arguments as mathematical probabilities. Short of that, however, this skeptic calls it hand-waving. And there appears no evidence that Swinburne dove head-first into a logical justification for numerical assignment of probabilities. Read the second short passage I quoted near the top for confirmation.
As the reviewer admits, Swinburne gives us a lot of food for thought, in the form of evidence to consider that Jesus was God incarnate. As the reviewer implies, these pseudo-probabilities do nothing to clarify or strengthen Swinburne's argument. I'm sure the ever-lucid Swinburne had a reason for doing this, but it is simply beyond me at the moment:
Another way of putting this would be to say that Swinburne’s argument is unsuccessful if dealing with logical probabilities, but we can instead interpret it as describing Swinburne’s own subjective probabilities or degrees of belief. If probability, like logic, places constraints on rational belief, Swinburne’s argument can be seen as supporting that it is epistemically permissible to believe in the resurrection of God incarnate.
Regardless of whether he's rational, he's not being logical. No one has been able to define God's essence, only its attributes, which are mostly a lack of limits. People say God is supernatural but what does that really mean other than not-natural? They say God is spirit, not body but that just means God lacks matter, lacks a physical substance, lacks any biological reality. What does it mean to have a mind and no matter? Nobody knows. It's outside our experience, so it makes no sense to assign numbers of probability to something so far removed from anyone's experience or knowledge. --Lynne
ReplyDeleteHey guys, I can prove Christianity false! It turns out that this is not as original as I first thought because it's really just a version of the Argument From Physical Minds. But it works:
ReplyDelete1-Eternal life is so central a tenet of Christianity that Christianity could be proven false if eternal life is proven false.
2-The body does not survive death.
3-Therefore, for eternal life to exist, people must have souls.
4-The soul must be or represent the Self. Otherwise, losing one's soul would be no worse than losing one's hair. (Losing one's hair would even be worse because we would be aware of its loss.)
5-Your Self is not yourself unless it includes your personality.
6-By definition, souls escape bodily death unharmed.
7-Anything that escapes bodily death unharmed must also escape bodily injury unharmed.
8-One's personality can be radically altered by injury to or disease of the brain. Alzheimer's disease is one example.
9-Therefore, there is no eternal life.
10-Therefore, Christianity is false.
--Lynne
This comment has been removed by a blog administrator.
ReplyDeleteGene Witmer said...
ReplyDeleteDan,
If I follow you, the main problem you have with the way Swinburne is doing things here is the fact that he wants to assign specific numerical probabilities to certain propositions, where it seems to you that such assignments don't make any good sense. For instance, you wrote:
"As a scientist who works with numbers fairly regularly, I cannot quite comprehend the ease with which Swinburne takes his assignment of numerical values as legit. He would have to lay out a formal system for assigning probability using either fuzzy logic or something, which our reviewer doesn't hint at."
You also wrote:
"His numbers are no stronger or weaker than the arguments themselves, and do nothing to strengthen or weaken the premises therein. I just don't get it -- he lays out the case quite nicely elsewhere without resorting to...what seems...an attempt at making quantifiable concepts which do not reduce to discrete values."
You're right that his numbers are no stronger or weaker than the arguments themselves. And you're right, I think, to be wary of numerical representations of what has been achieved. It's a good idea always to beware of such representations, as dressing points up in numerical garb often has an unduly intimidating effect. People see numbers and think "How scientific and precise!" and are less likely to assess the evidence with a fair and critical eye. Indeed, it looks to me like that's what happened with the CNN article. The reporter simply found it astonishing that a subject matter like this might be set out using numbers and thought it must be an amazing, overwhelming argument. But most of the action is really elsewhere; the numbers are not the interesting thing; if there's something interesting on offer, it can't be understood simply by examining the numbers.
In any case, I do want to say something in Swinburne's defense here -- specifically his use of numbers. The first point to note is this: If he were to say that his arguments demonstrate that the probability of, say, God's existence is precisely 50%, then that would be absurd. Regardless of how good or bad those arguments are, it is simply unbelievable that they would establish a precise probability. Why .5 as opposed to .55? or .51? or .50001?
So how could one make use of these numbers in the first place? Here's how: Instead of saying that these are the probabilities, say that the actual probabilities are at least this much. As a matter of dialectics -- that is, persuasive argumentation -- this is a perfectly sensible thing to do. Suppose I am trying to convince you that P, and I have as premise Q1, Q2, ... Qn Now suppose that you are dubious about Q1; you see some reason to accept Q1, but you still think there's a substantial chance that it's false. Now I might ask you: Well, how likely do you think Q is? Do you think that Q1 is roughly 60% likely? If you sound like something around this is right, then I may quite sensibly go on to say: Well, let's assume then, to be on the safe side, that Q1 is at least 40% likely and proceed from there. Nothing in this procedure requires that anyone take a stand on an exact numerical assignment.
The second point to note then is this: If it's legitimate to specify "at least" probabilities in this fashion, one can then make use of those and the probability calculus to conclude that other propositions have an "at least" chance of being true, where it's significant that we get that result. Suppose we had arrived at some "safe" probabilities for all of Q1-Qn and calculate that P is at least 97% likely. It doesn't matter that the real probability is not precisely 97%; that will still be a very impressive result.
I take it that this is the sort of use Swinburne is making of the assigned probabilities, and it does seem legitimate to me. Of course, the initial assignment depends on what you think is a safe probability assignment in light of the evidence and arguments, and here, of course, is where the real action is. Focusing on the numbers is a secondary enterprise. It helps primarily by enabling one to sum up the cumulative effect of several different bits of argument and evidence.
So, I hope this helps in seeing how one could make sensible use of such numbers without having to introduce the formalities of fuzzy math or the like. My main point, in any case, was that Swinburne is not relying on the sort of logic that Chu-Carroll was attributing. Now, you say something in your post to suggest that he really is making use of such logic. You quote the reviewer:
Swinburne claims his probabilities are to be viewed as epistemic or logical probabilities. According to Swinburne, it is a logical truth, necessarily true or necessarily false, that some evidence makes a certain proposition likely to some degree. Although it is controversial whether an adequate account of epistemic or logical probability can be developed, there must be some clear connection between rational belief and any account of epistemic or logical probability in order for the concept to be of any use.
You then comment that "this very paragraph hits at Mark Chu-Carroll's treatment." (Did you mean "hints at"?)
I take it you are interpreting those comments as showing that Swinburne really does depend on the presumption that it's valid to infer from "either P or not P" to "P has a .5 chance and -P has a .5 chance." But that is not how to read those comments. Calling the probabilities "epistemic" or "logical" does not amount to saying that they are determined solely by such facts. Notice what it is that the reviewer describes as a necessary truth: "that some evidence makes a certain proposition likely to some degree." The claim is that there is a necessary truth of the form: Given evidence E, the rational assignment of likelihood to proposition P is N. The claim is not that one can determine the probability of P, period, by just examining the logical space around P -- that is, by just consider the logically possible alternates to P's being true.
What should we make of the reviewer's remarks here?
Another way of putting this would be to say that Swinburne’s argument is unsuccessful if dealing with logical probabilities, but we can instead interpret it as describing Swinburne’s own subjective probabilities or degrees of belief. If probability, like logic, places constraints on rational belief, Swinburne’s argument can be seen as supporting that it is epistemically permissible to believe in the resurrection of God incarnate.
The claim here is not that it's unreasonable for Swinburne to use numerical assignments of probability at all; the suggestion is rather that, instead of saying that the probability of P given E is N, period, as if this were a general fact independent of people, Swinburne could say that he personally finds the likelihood of P given E to be N. This would still be an interestingly point to make if one thinks that others are likely to agree with such estimates of likelihood, since then they will be constrained, by consistency, to conclude that the overall probability of his desired conclusion is at least as high as he says it is. One could just revise one's earlier estimates of likelihood, however, and regain consistency.
Hope this helps clarify things. I find it a bit amusing to be in the position of defending a theist, but I felt a bit obliged, especially after you introduced this by relating my recommendation of Swinburne as one of the more intelligent and sophisticated theists out there!
-GW
Well maybe the article also was wrong about the Swinburne's purpose in laying out these numbers. The reporter touted it as proof of the resurrection. If Swinburne is actually saying that, then he hasn't proven anything since his numbers are entirely subjective based on his opinions about how likely something is. Any one of us could come up with completely different answers and a completely different conclusion.
ReplyDeleteOn the other hand, if all he's doing is saying given a belief in the Christian God, it's reasonable to assume the resurrection happened, well so what? Without the resurrection Christianity would not be...well, Christianity. So we already knew this.
Professor,
ReplyDeleteI find it a bit amusing to be in the position of defending a theist, but I felt a bit obliged, especially after you introduced this by relating my recommendation of Swinburne as one of the more intelligent and sophisticated theists out there!
I understand your position. You don't have to feel that I think your recommendation was in error. On the contrary, I agree with you that Swinburne's arguments are among [or are] the best for the existence of God. That is one reason I was surprised to see this.
I take it you are interpreting those comments as showing that Swinburne really does depend on the presumption that it's valid to infer from "either P or not P" to "P has a .5 chance and -P has a .5 chance." But that is not how to read those comments.
Indeed, that it exactly what I meant when I said he had "lost his marbles", and the reason for Chu-Carroll's facetious refutation of the [il]logic.
Upon close inspection, I will admit that I need the book to see what Swinburne is really saying here:
"...Swinburne concludes that the probability that God will become incarnate, if he exists, is 1/2: “Again, so as not to exaggerate my case, let me suggest that these reasons make it as probable as not that, if there is a God, he will become incarnate . . . .” (p. 50)."
I will admit that Swinburne's logic is not relying upon an "excluded middle" sort of extrapolation [as you highlighted above]. I will admit this is an unfair characterization.
Regarding the strangeness of the attribution of the value n = 2, (given a probability of P = 1 / n) though, I suppose I must simply agree with the reviewer:
"However, I found it difficult to see why these reasons make it as likely as not that God would become incarnate if he exists. Swinburne himself discusses a couple of plausible alternatives to becoming incarnate as the best act for God to do, and readers may think of several more. He endorses a form of the principle of indifference applied to God’s actions, and thus one would expect Swinburne to conclude that the probability of God becoming incarnate (given that he exists) is about 1/n, where n is the number of equally best acts that God could do (p. 34). Given this, it is difficult to see why Swinburne concludes the probability of God becoming incarnate, if he exists, is 1/2 instead of 1/3, and many readers will assign an even lower probability."
The number of "plausible alternatives" when we are discussing a God who is, definitionally, limitless, would rationally be n = a huge number. Furthermore, in Swinburne's rationale for God becoming incarnate, it appears he begs the question rather badly, by assuming that God wants to/needs to/must/will/should 1) "atone", 2) "suffer", and 3) encourage a certain way of living in us, as he is presupposing the Xian worldview, in an attempt to argue for the Xian worldview.
At any rate, I appreciate your defense of the mischaracterization. I also learned a lot from the exchange. Please do drop back in on us from time to time, and feel free to post anything you like, or send it to me as a Word file or something, and I'll post it for you.
Cheers!
D
Lynne,
ReplyDeleteSorry I didn't reply earlier. I largely looked over your argument in my haste to respond to Prof. Witmer.
I think that p7 and p8 are where you would get into trouble with a dualist [whether theist or not]. Many of them use analogies likened to cordless phone calls, where the signal itself moves through a medium [say, a wire] separate from both the phone receiving the call, and from the phone placing the call [for simplicity's sake, let's say both are cordless].
Now, if the transmitter (the caller) continues to attempt to get the receiver (the callee) but the callee has thrown his phone out a window, breaking it, the dualist argues that the signal is still present, there is just no way to get it through to the phone. In the same way, they argue that a defective brain, the "receiver" of the mind [transmitted through some medium: the interface that allows immaterial substance to interact/cause material substance to act--as yet unnamed and undefined], fails to represent the true, intact, unharmed mind/personality beneath.
Pretty unfalsifiable scientifically, so I typically treat it as I do all unfalsifiable arguments: interesting conjecture. I am a skeptic, so, I need some good reason to think that this signal is still there, or ever was. That's why I'm a physicalist. The best arguments I've found for dualism can be handled via property dualism or emergent dualism, and it seems those are still compatible with naturalism. "Emergence" and "epiphenomenalism" are the two ways [almost the same] to defend physicalism against nearly any dualist arguments.
It appears that philosophers of the mind are nearly all arguing these days on whether or not mental states are reducible to physical states, but nearly none of them believe in some kind of Christian worldview, or a soul.
Mark CC has written in more detail on the topic.
ReplyDelete