Richard Dawkins’ new children’s book, The Magic of
Reductionism Reality has a really useful chapter on miracles. Dawkins bases much of his position on Hume’s argument against miracles:
Hume didn’t come right out and say miracles are impossible. Instead he asked us to think of a miracle as an improbable event – an event whose improbability we might estimate. The estimate doesn’t have to be exact. It’s enough that the improbability of a suggested miracle can be roughly placed on some sort of scale, and then compared with an alternative explanation such as hallucination or a lie. (p. 259)
This is helpful as it gives a mathematical definition of miracle based on probability theory. Something with an unrealistically low probability must have an alternative, more probable explanation. He gives a direct example:
If John tells you a miracle story, you should believe it only if it would be even more of a miracle for it to be a lie (or a mistake, or an illusion)… No matter how trustworthy and honest John might normally be, the idea of his telling a lie (or having an honest hallucination) would be less of a miracle than a cow jumping over the moon. (p.254)
Dawkins also gives three possible explanations for an extremely improbable hand of cards (all the suits in order) being dealt. It could either be (1) a miracle, or (2) a remarkable coincidence, or (3) a clever conjuring trick – in other words, a lie. The last, he says, is far and away the most likely explanation.
This has some very useful applications to science. If, for example, Eugene Koonin were to tell you that the odds of DNA replication arising are so astronomically small that one has to imagine a many-worlds multiverse to explain it, then one knows he’s either lying, doing a conjuring trick or, perhaps, having an honest hallucination. The multiverse explanation, of course, does not decrease the odds, but simply makes impossible odds (such as those involved in a cow jumping over the moon) possible, so is as improbable as a miracle would be.
Or you could take the example of cosmic fine-tuning. Anybody suggesting that the Universe just happened that way, despite the astronomical odds, falls under Dawkins’ excluded second suggestion – “remarkable coincidence” (only this time in spades).
Most convenient of all his words speak to his own suggestion that random mutation alone would generate tiny probabilities of life emerging or evolving, but that natural selection solves the problem. In this case, we can dismiss his concept of natural selection from the maths since chance has to make the changes before they can be selected (thus it is akin to saying, as has been pointed out, that you can bypass the odds of winning a £1m lottery prize by simply winning 10,000 £100 prizes instead). Thus Dawkins has fallen into the category of making a mistake (although, as in the case of his “John”, his previous propensity to tell the truth should not dissuade you from suspecting him of lying if he’s asking you to accept an event with such impossible odds).
Dawkins adds another point, which he would probably prefer to apply to the situations I have mentioned:
Suppose something happens that we don’t understand, and we can’t see how it could be fraud or trickery or lies: would it ever be right to conclude that it must be supernatural? No! As I explained in Chapter 1, that would put an end to all further discussion and investigation, It would be lazy, even dishonest, for it amounts to a claim that no natural explanation will ever be possible. (p. 263)
Here, of course we have to respectfully disagree with Dawkins on philosophical grounds. To dismiss an explanation with infeasible odds (such as a miracle or random events leading to life) in favour of an explanation with no calculable odds at all (“Someday there will be a natural explanation”) is an argument from ignorance. Bearing in mind how little we know, there may well be many things in the world that can never be explained by natural causes. It will always be possible, though, to imagine that any number of causes may be hiding somewhere in the future.
But imagination is no explanation at all – and therefore, by Hume’s and Dawkins’ logic, a worse explanation than a miracle.