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David Cameron's fallacy

I was glad to hear an item on yesterday's Today programme pointing out the logical error in David Cameron's claim that couples who are married are more likely to stay together and have healthier and more successful children. The obvious fallacy in this is that the correlation, even if true, does not prove cause and effect. It is surely more likely that those couples who marry are already in a more stable relationship.

New light on a 'miracle'

In 1875 a Flemish labourer called Pierre de Rudder visited a local replica of the Lourdes Grotto, and apparently experienced the instantaneous healing of an ununited and infected fracture of the tibia and fibula. A section of bone was entirely missing, yet a photograph shows the leg not only whole but equal in length to the opposite leg. The healing was certified by physicians and, when Rudder died, post-mortem examination showed the bones were united and of normal length.

In her book on Lourdes, Lourdes: Body and Spirit in the Secular Age, Ruth Harris, who is not a Catholic, says that the case "dismays and perplexes".

I agree it does, but it happened a long time ago and it is always difficult to know what to say about one-off cases. Fortunately, new light is shed by an article by Joe Nickell in the current issue of Skeptical Inquirer (Vol. 34, No. 1). Nickell twice visited Belgium to investigate alleged miracles. One of these was the de Rudder case.

In outline, he has found documentary evidence which, together with the bones themselves (which show impaired alignment at the fracture site), suggest that the healing was not in fact instantaneous and might have occurred naturally before de Rudder visited the shrine. Prior to the visit he used to perform a stunt in which he demonstrated almost 180 degree rotation of the leg at the fracture site, but this was always with the limb clothed and Nickell thinks that he may have simply had unusually lax ligaments and that there may have been an element of malingering . De Rudder was in receipt of a pension from the viscount who employed him but this ceased when the viscount died; a 'miraculous' recovery would allow him to return to work without admitting he had been a fraud.

I'm glad to have this information, because I have elsewhere published my view that apparently miraculous healings are usually of disorders (including cancer) that may on occasion recover naturally. The de Rudder case might have posed a challenge to this view, but Nicholl's research offers the possibility of a plausible natural explanation.

Free will and the brain

More than 20 years ago Benjamin Libet did research which showed that the electrical changes in the brain that accompany voluntary action occur at least half a second before people are aware of forming the intention. Many thought that this work invalidated free will, although Libet himself wished to reconcile his discovery with freedom of the will.

Recent work by John-Dylan Haynes and colleagues in Germany has shown that the brain changes occur even earlier than Libet found - up to 7 seconds before people are aware of making a decision! This makes free will look even more doubtful, although Haynes does point out that the possibility that we can prevent an action from occurring has not yet been ruled out. See

One mistake we should avoid is supposing that it is the brain changes themselves that are central to the free will question. Even if there were a 'soul' hovering over the body and influencing its choices, the free will problem would remain. Presumably the decisions taken would be determined by the previous experiences and psychological make-up of the soul so would not be really free. The only kind of freedom one could imagine would be if the choices were random, which is hardly better than determinism.

The new research fits in well with what Daniel M.Wegner writes in The Illusion of Conscious Will, which I strongly recommend to anyone who, like me, has puzzled over such matters for many years.

For a philosophical explanation of Libet's work which I, at least, find persuasive, see Chapter 8 of Daniel Dennet's Freedom Evolves. He finds that our understanding of the research is affected by our adherence to what he calls the Cartesian Theatre. That is, we often suppose that there is some central coordinating agency, some "place" in the brain where conscious decision-making takes place. Dennett takes this to be an illusion, and the same applies to the assumption that there is some "time t" at which a decision occurs. I should say that this section by itself makes the book well worth reading, whether or not you are fully persuaded by Dennett's account of free will.

The "Hobbit"

Today's Independent has a piece about the diminutive female skeleton found on the island of Flores and nicknamed the Hobbit. Since her discovery argument has raged among the experts about whether she was a pathological specimen, perhaps suffering from microcephaly, or represents a different type of human. The article implies that opinion is now favouring the human idea. Either she was a dwarf form of Homo sapiens or, even more exciting, she could have been a descendant of Homo erectus on a separate line from us.

I hope this is correct. It's delightful to think that a version of Homo erectus was around as late as 18,000 years ago, pursuing the pygmy elephants that also lived on the island.

Andrew Brown's blog

I don't read The Guardian regularly so this is why I hadn't come across Andrew Brown's blog on religion previously. He is apparently an atheist who takes religion seriously. See, for example, his entry on "Why I am not a Christian" for 31 October 2008. I don't agree with all he says, naturally, but I recommend his blog to anyone who, like me, subscribes to the naturalist viewpoint but doesn't think that people who believe in religion are automatically to be classed as fools or deluded. The questions that Christianity poses are real even if I don't agree with the answers it gives to them.

Justin Barrett and Lewis Wolpert on belief in God

I was listening to the Today programme this morning, in which there was a brief discussion between Justin Barrett and Lewis Wolpert about Barret's view that young children have a natural tendency to believe in a god (or gods?). Although the discussion was supposed to provide a conflict of views, there didn't seem to be much disagreement between the two. Barrett was not saying that the existence of such a tendency had any theological implications, simply that it was a psychological characteristic.

Wolpert's argument was that children had a natural tendency to see intention in natural phenomena, which I think is correct. When I was five I had worked out a theory about what causes the wind: I thought it was caused by the branches of trees waving about. This seemed quite logical: I knew that I could produce wind by waving my arms, so presumably trees could do the same on a larger scale. And certainly the branches did move about when it was windy and not at other times.

I proposed this theory to adults and it they rejected it, but I was not entirely convinced that they were right.

Much of early religion was presumably based on a similar tendency to animistic thinking; it is not a big step to go from thinking that trees have minds and purposes to believe that rocks and streams do too.

Brian Appleyard on Creationism

I turn on the Today programme this morning and there is Brian Appleyard arguing about creationism with Prof. Chris Higgins. As usual, Appleyard made my hackles rise, which I am sure is a good thing, if only because it makes me clarify my own ideas.

The reason for having this discussion was the recent resignation of Professor Riess, director of education at the Royal Society (I didn't even know they had a director of education). Anyway, what I am writing about here is not whether Riess should have resigned (I don't actually think he said anything exceptional) but what Appleyard said in the closing moments of the discussion.

Higgins said that creationism is nonsense. Appleyard didn't actually say it was true -- he's too clever for that -- but he said that it is a legitimate way of viewing the world, rather like the ancient Greek gods. (There are actually people in Greece these days who apparently take the old gods seriously.) 'Science needs to accept that there alternative ways of viewing the world.'

So presumably we should accept not just ancient Hebrew mythology but all the other mythologies that have been propounded over the millennia (all those we know about -- most have disappeared without trace) as equally valid descriptions of the world along with the scientific view. I agree with Higgins that this is nonsensical.

Scientific theories are, by definition, always provisional, but -- unlike mythologies -- they are testable and self-correcting. And I am sure there is such a thing as objective truth, an accurate description of how things are, which we can approach even though we may never reach it finally.

Induction and the black swan example

The problem of induction is often illustrated by means of the black swan example. We used to believe that all swans are white, because all those we had seen were white. But then we went to Australia and saw black swans there, so our earlier rule was shown to be wrong. Our earlier belief is supposed to be arrived at by induction.

I find a difficulty with this example. What it really shows, I think, is that such things are matters of definition. We define a swan as a large bird with a long neck that swims on water. Whether we choose to add the item of its colour as part of the description is up to us. Before we went to Australia we probably would include the colour. When we see a bird which is otherwise identical to what we describe as a swan except that it is is black, it is a matter of convention whether we call it a swan. If we wished we could call it a 'swin', which would then be a bird which looks like a swan except that it is black. If we adopt the term 'swin' for these black birds, we could continue to say that all swans are white. Whether we choose to do so or not is simply a question of convenience.

If we encountered a white bird which looked like a swan but never entered the water, would we call it a swan?