William Lane Craig vs. Stephen Law: Another Case of One Man’s Modus Ponens is Another Man’s Modus Tollens

In October of 2011, William Lane Craig squared off with Stephen Law about the existence of God (video above). Law advanced the hypothesis of an evil god, arguing that just as theodicies aimed at reconciling a good God with evil could be offered, so could “theodicies” aimed at reconciling a evil god with good be offered. This possibility is supposed to discredit theodicies for a good God. Craig accepts that the evil god theodicies are possible, and that is not unreasonable to accept the possibility of an evil god.

During the rebuttals, it seemed that both Law and Craig were talking past each other. Here’s my attempt to clarify. I think it’s yet another case of “one man’s modus ponens is another man’s modus tollens.” (Hereafter MPMT) In this case I’ll start with  modus tollens first. According to Law:

(1) If theodicies for an evil god can be reasonable, then it’s reasonable to accept the possibility of an evil god.

(2) It’s not reasonable to accept the possibility of an evil god.

(3) Therefore, theodicies for an evil god cannot be reasonable.

Then he continues:

(4) If theodicies for an evil God cannot be reasonable, theodicies for a good God cannot be reasonable.

(5) Therefore, theodicies for a good God cannot be reasonable.

(6) Therefore, it is unreasonable to believe in God.

Most of this is pretty self-explanatory, except (4). One would have to argue that the theodices for a good an evil god are similar enough to support this premise.

Craig’s modus ponens:

(1) If theodicies for an evil god can be reasonable, then it’s reasonable to accept the possibility of an evil god.

(2′) Theodicies for an evil god can be reasonable.

(3′) Therefore, it is reasonable to accept the possibility of an evil god.

And, of course, if Craig’s counter goes through, then (4-6) of Law’s argument breaks down.

Law seemed pretty frustrated with this reply, but didn’t really clearly attempt to refute it. He merely insisted that this wasn’t the way to interpret his argument.

That sort of reply isn’t acceptable. Craig offered a counter argument (on my interpretation), one that needs to be answered. And, as in any case of MPMT, it is a contest between (2) and (2′). Law assumed, and insisted on, (2), but provided no real argument for it. Craig didn’t really argue for (2′) either.

Yet, because Law was on the offence here, I think he needs to support (2). Right now it’s merely an assertion, one that carries a lot of weight in his argument. Craig doesn’t have to accept it. Unless Law supports the idea that the possibility of an evil God is unreasonable (good luck with that — even Descartes struggled with that one), there is no real force behind his argument as a whole.

Perhaps Law is thinking that belief in God in general, whether good or bad, is ridiculous. He’d be in the company of most atheists: they believe God is inherently (apart from any evidence) implausible, (note the many comparisons of God with the Flying Spaghetti Monster). But that’s just an atheist thing. You can’t just assume this in a debate about God without begging the question.

 

Advertisements

Why Historians Reject the Resurrection of Jesus: It’s a Miracle

David Hume, a pillar of skepticism
David Hume, a pillar of skepticism

For a little background, check out this debate between Christian philosopher and apologist William Lane Craig and the skeptical historian Bart Ehrman. Craig argues that Jesus rose from the dead, claiming that God raising Jesus from the dead is the best explanation for these facts:

1. Jesus’ burial
2. the discovery of the empty tomb
3. his postmortem appearances (at least in the minds of the disciples)
4. the origin of the disciples’ belief in his resurrection

What is interesting is that in the debates against Craig, the core of the response of Craig’s opponents isn’t about disputing these facts. Their main argument is that God’s raising Jesus from the dead (call this the Resurrection Hypothesis, or RH) is not historical because it is a miracle claim.

One might think that this is just anti-religious prejudice. But they do offer a philosophical argument for the prejudice. It’s the 18th century philosopher David Hume’s argument against belief in miracles (Ehrman in the above debate denies this, but his argument is pretty much a simplified version of Hume’s argument).

What is Hume’s argument? Here’s a quote:

When anyone tells me, that he saw a dead man restored to life, I immediately consider with myself, whether it be more probable, that this person should either deceive or be deceived, or that the fact, which he relates, should really have happened. I weigh the one miracle against the other; and according to the superiority, which I discover, I pronounce my decision, and always reject the greater miracle. If the falsehood of his testimony would be more miraculous, than the event which he relates; then, and not till then, can he pretend to command my belief or opinion. (Hume 1748/2000: 87–88)

There is much dispute between Hume scholars about what this argument amounts to (see this article in the Stanford Encyclopedia of Philosophy). But let’s consider this question using probability theory.

I have two versions of what follows, hard, and easy. Here’s hard (skip if you don’t want to go through the math):

Consider one formulation of Bayes’ Theorem:

P(RH|E) = P(RH) × P(E|RH)/P(E)

I’ll describe what this means. RH = God raised Jesus from the dead. E is the evidence now under consideration (background information understood to be always there and is not included in the formula). P(RH) is the probability of RH just in itself, without considering the evidence at hand (This is called the “prior probability”). P(RH|E) is the probability of RH given E (the probability of RH given the evidence). P(E|RH) is the probability of the evidence occurring if RH is true. This term is about the explanatory power of RH — RH accounts for E if RH gives one reason to expect E. That is, if RH gives us reason to expect E, then E’s occurring is evidence for RH. Finally, P(E) is the probability of E just given the background information. It is to normalize the equation. There is also the intuition that P(E|RH), even if high, wouldn’t mean much if we would expect E to happen anyway. Thus we divide P(E|RH) by P(E).

My own view is that Hume’s argument amounts to this: P(RH) is extremely low. That is, the probability of a miracle occurring, given our background information (including all of science), is low, for miracles are, by definition, a violation of the regularities of experience. Thus all of experience stands against them. If that’s true, then P(E|RH)/P(E) would have to be extraordinarily high to compensate if the Resurrection is to have any real probability of happening. In the real world no one could supply such evidence.

Here’s easy:

Two main things go into how probable some statement is given the evidence. The first is how inherently likely the statement is, without considering evidence. Let’s call this the prior probability. The second is how much does the evidence support the statement. With miracles, skeptics, like Hume, argue that their prior probability is sooooo low that no amount of evidence can make them reasonable to accept. The Resurrection of Jesus is no exception. We could grant that the evidence does give some support for the claim, but still reject the claim because it’s so inherently unlikely. It’s like trying to prove that someone saw an alien. The evidence that would be enough for an ordinary event wouldn’t be enough for something extraordinary like the appearance of an alien. As atheists and skeptics often say, “Extraordinary claims demand extraordinary evidence.”

Back to the main topic:

Though skeptics might admit that natural alternative explanations of the data surrounding Jesus’ resurrection have so far been disappointing, they would insist that even the worst of these is better than the Resurrection (Ehrman was explicit about this), presumably because of the Resurrection’s low prior probability.

Craig admits that, just by itself, the Resurrection is very improbable. Craig asserts, however, that he isn’t arguing merely that Jesus rose from the dead, but that God raised Jesus from the dead.1 This latter statement, at first, seems to have a higher prior probability: God would have the power to do something that has no precedent in experience. A skeptic, however, could reply that adding God into the hypothesis makes it more complex, lowering the prior probability. The more ad hoc additions we make to a theory, the worse it is in terms of prior probability.

Notwithstanding, Craig spends most of his time arguing for a high value for P(E|RH)/P(E) (arguing that the evidence is well explained by the hypothesis) — he argues that the evidence given above is far more probable on the Resurrection than on any natural hypothesis. But all this falls on deaf ears because of the low value of P(RH) (low prior probability).

What can be said? I think that P(RH) (the Resurrection’s prior probability) is low given naturalism. Adding God to the hypothesis seems ad hoc. But what if we had independent evidence for God’s existence? If God exists, then, given His goodness and the evil in the world, we might expect some sort of action on his part to address this evil. In particular, we could expect some sort of revelation. And for us to know the revelation was from God, we might expect some sort of miracle to validate the revelation. So we would be expecting something like RH (the Resurrection Hypotheis).2 This wouldn’t show that Jesus rose from the dead, but it would mitigate the low prior probability for RH: God wouldn’t just be some add on, but something independently supported. Then evidence for the Resurrection could be taken more seriously.

Thus I think that the case for Jesus’ resurrection by God needs to be made as part of a comprehensive case for Christianity. This would include a case for God’s existence as the best way to account for all the data of our experience (including our apprehension of a realm of value, our experience of ourselves as immaterial beings, the existence and fine-tuning of the universe, etc). This is, of course, what Craig does in God debates. However, I don’t think it appropriate to use Jesus’ resurrection as evidence for God (as Craig does) simply because Jesus’ resurrection would only be the best explanation for the facts he presents as evidence if we already knew that God exits. It would be a circular (or pretty close to circular) argument. I would instead try to argue for God’s existence, then, if successful, use evidence for the Resurrection to support the truth of Christianity.

  1. Craig also denies that Bayes’ theorem is applicable to historical analysis, as these probabilities cannot be determined. See his debate with Greg Cavin here: https://www.youtube.com/watch?v=Rmxi9o_xqkc.
  2. Similar ideas are worked out in Richard Swinburne’s Revelation.