Discussing Dawkins.

Very few of the responses to 'the God delusion' that I have come across deal with the main argument it presents. So I was very pleased to see that the Faraday institute had arranged a discussion on that very issue. If you're not familiar with the argument, you should probably have a look at it before reading on.

Unfortunately, the discussion was unsatisfying for a couple of reasons. First, the format led to the speakers talking past, rather than to, each other. Second, nobody who spoke accepted that Dawkins' argument was valid. I don't think it is valid either, but I would have liked to know how those who do accept it defend it. I had hoped that a discussion of the argument would involve a speaker who accepted it. In any case, it is worth exploring some of the ideas that were introduced.

The discussion began with each of the two main speakers giving a 20 minute presentation. Richard Swinburne, a prominent opponent of Dawkins, was up first. Swinburne mentioned that he did not accept Dawkins' argument, but did not explain where the problem is. He spoke on a related theme, reiterating an argument he had proposed before 'The God Delusion' was written. The main link, apart from the similarity of form, seems to be that this argument was criticised in the chapter of TGD that contains the key argument.

The argument may be summarised by the phrase 'Theism is a simple explanation'. After a digression on the nature of scientific explanations (which I will not go into; it isn't relevant to the argument, and better accounts of scientific explanation exist), Swinburne introduced the following criteria for accepting that a hypothesis is true, given some evidence:

1. The evidence should be a likely outcome, given the truth of the hypothesis.
2. The evidence should be an unlikely outcome, given the falsehood of the hypothesis.
3. The hypothesis should be simple.
4. The hypothesis should fit in with our background knowledge.

He then mentioned that if we're looking for a theory of everything, the fourth criterion is irrelevant. He introduced some evidence; there are beings to whom the universe is rationally intelligible. He also introduced a hypothesis: 'There is a God, omnipotent, omniscient and perfectly free.' He checked the criteria:

1. Being free, God will not be limited by irrational inclinations: He will act rationally. Being omnipotent, God will have perfect moral knowledge. Being rational, God will wish to do what is good. Being omnipotent, God will do what is good. It is good to create other beings, in order to do them good. This involves creating a universe for them to live in. It is good to make that universe rationally intelligible to them. So God will do so.
2. The world is a complicated place. It is unlikely to have come into existence by chance.
3. Only one being, with 3 qualities, is hypothesized.
   

It is worth noting that the argument relies on the simplicity only of a hypothesis about God, whereas Dawkins' claim was that God Himself, rather than any hypothesis about Him, was necessarily complex.

Next in line was Colin Howson, an atheist philosopher. He had prepared a powerpoint presentation beforehand. He reviewed Dawkins' argument, and rejected it on the grounds that there is no need to consider how complex God is to obtain a probability of His existing by chance; he claimed that this probability is automatically 0. Thankfully, he had anticipated the argument Swinburne presented, and he argued against it.

I'll modify the terms of the argument, and the order of presentation, (though hopefully not the ideas) to fit in more closely with the phraseology above. Howson explained that the three criteria introduced above can be made precise in the framework of Bayesian inference. The first two criteria correspond to features of the calculation, whilst the third criterion corresponds to the idea of assigning prior probabilities to hypotheses on the basis of simplicity. He then attacked the three criteria individually:

1. On the basis of the hypothesis, we would expect the world to be a good place. But when we observe it, we find that it doesn't look that way. This is the problem of evil. Also, there are many conceivable universes containing beings which rationally comprehend them; So the possibility of our universe, even given this explanation, is tiny.
   
2. It is impossible in principle to assign a probability here; we don't know what the alternative explanations are. They certainly aren't limited to 'chance'. Scientists have had to be more imaginative than science fiction writers, to explain the real world. We must accept our poverty of imagination. We don't know the alternatives; we may not even be able to.
   
3. We have observed that assigning prior probabilities on the basis of simplicity is a good idea for explaining things within the world; the history of science is full of examples. But it is the world itself, including the history of science, which is to be explained. So any recourse to that history would be circular. There doesn't seem to be a reason why simplicity is intrinsically more probable than complexity.

This approach also knocks down any attempt to give a similar objective justification for science. But there is no need for science to be justified by such an abstract philosophical foundation.

At this point, the three interlocutors were each allowed to make a brief speech. Though they were in agreement that all three of Dawkins, Swinburne and Howson were wrong, they did not have time to adequately explain why. Indeed, the two main speakers did not take long to point out that the objections they had managed to articulate were simply missing the point. I've tried to phrase the above summary in such a way as to avoid similar misunderstandings, in order not to have to present them and pull them apart here.

The two main speakers were then left with 3 minutes each to deal with the points that had been raised. Swinburne mentioned that he could resolve the problem of evil, though not within 3 minutes. Howson expressed his doubts. That, apart from explaining what the interlocuters had misunderstood, was all they had time for.

Then there was a question time. I raised an objection to Howson's attack on the second criterion. We may not know what the possible explanations there are, but we can surely put crude bounds on the number of explanations of any given simplicity. For example, an explanation that cannot be described in English in a space shorter than the encyclopædia brittanica can hardly be described as simple, and we can put a bound on the number of remaining explanations. It's possible that we can do this in such a way as to put a lower bound on the probability of the hypothesis of theism. His response, that a simple explanation may require a high-level language for its expression, ignores the fact that high-level languages may be introduced and used within English. The process is called giving definitions. Soon after this, I had to leave early to get to a bible study group. The speakers never had a chance to develop the discussion, but I think there are some more ideas to be explored here.

The argument about the first criterion can certainly be developed. Howson pointed out that the hypothesis of theism simply does not explain physical events as precisely as modern physics; the universe we see is so specific that it is still highly improbable under this hypothesis. Swinburne never explicitly claimed it explained anything more than the existence of beings capable of rationally understanding the universe: He just hinted at it.

Now that these hints have been laid to rest, the evidence being explained can be seen to be simpler than the proposed explanation. After all, the explanation includes the idea of a being who is capable of rationally understanding all things (that's a small part of omniscience). But the explanation also relies on the existence of absolute moral truth. Although the problem of evil can be resolved (I've outlined one attack in an earlier post), the difficulty of the resolution shows that this moral truth is not as simple as it might at first appear, and accordingly brings out some of the complexity of the proposed explanation.

As Howson pointed out, we don't really have justification for assigning prior probabilities on the basis of simplicity. Indeed, why should we be able to assign probabilities at all? The idea of probability makes sense in the context of tossing a coin. We have a reasonable understanding of coins, and of how they behave. This ultimately relies on some crude understanding of how the world works. It is on the basis of such an understanding that we can assign probabilities. So we can't assign probabilities to such understandings, except on the basis of better ones. We can't assign probabilities to ultimate understandings at all; it doesn't make sense.

For a test case, consider the probability that there is a physical world at all. We have masses of evidence, pushing this probability up to 1. But discounting this evidence, in the abstract, what is the probability? The question makes no sense. It stretches the notion of probability beyond its proper boundaries. In a similar way, the hypothesis of theism just doesn't have a probability in the abstract, apart from the evidence. Reasoning on the basis that it does is the shared flaw of the arguments given by Dawkins and Swinburne.