Posts Tagged ‘evolution’

The Anthropic Fallacy

December 1, 2009 5 comments

A couple of years ago, I attended a public lecture in Oxford given by Paul Davies, a professor of physics at various universities, including those of Queensland. and Arizona. He was on a lecture tour to promote his new book The Goldilocks Enigma, which addresses what appears to be a weirdly coincidental conundrum: that the universe – and planet Earth in particular – appears to be ‘just right’ for life to develop.

This claim is a variation on what is commonly known as The Anthropic Principle, and it has several real problems with it that classify it as an appeal to mysticism – the kind of populist tactic that has won Davies a lot of money from The Templeton Foundation. (The foundation makes a ridiculous attempt to unify science and religion, essentially bribing scientists to make vague religious claims for a million dollars.)

The core of Davies’s argument goes like this. The entire physics of the universe is based upon the values of only a handful of physical constants: things like the gravitational constant, the charge on the electron, the Plank constant, etc. This much is not in any doubt. If you were to change any of these constants, then the resulting physics would look different to how we see things in our universe, with our particular values for these constants. For some values, atoms would never form, making life as we know it (Jim) impossible, and in some, large molecules could never form, again stopping us from ever existing.

Look at our planet too – it’s just the right distance from the Sun to have liquid water on it, which appears to be essential for all the life we’ve so far discovered on it. Much further away, and we’d be frozen like Mars; much closer and we’d be roasted like Venus. Earth is in ‘The Goldilocks Zone’ – it’s just right for life. It also has an iron core, which gives it a magnetic field. This field deflects the high-energy solar particles, and stops them stripping away our atmosphere and our water. Perfect.

All these coincidences are adding up, aren’t they, and it’s tempting to stop for a moment and suspect that we’re a little bit special – the carefully prepared product of some guiding hand, perhaps…

But you’ve already probably spotted at least one of the problems with this kind of argument. Here are just a few:

  1. All the life on this planet is related – you only have to glance at the molecular evidence in the form of DNA. It’s all from the same stock, and is supported by the element carbon. We know of no other form of life, although some have suggested that silicon could possibly form the kind of complex, long-chain molecules that life needs, as carbon does. This tends to give us what is known as ‘carbon chauvinism’, in that there could be plenty of other intelligent beings that aren’t like us, and don’t require the kind of physical or chemical set-up we have here. Just because we don’t know about them doesn’t mean that they couldn’t exist.
  2. Hindsight gives a very illusory idea of cause and effect. Imagine you’ve hit a golf ball 300 yards and it comes to rest with a specific and unique alignment with the blades of grass it finally comes into contact with, as it inevitably must. The chances of exactly that configuration occurring is zero, considering the infinite number of alternative positions that the ball could have occupied. That doesn’t mean that it can’t have happened, though, or that it was somehow ‘planned’ because the ball has to end up somewhere, doesn’t it. It’s next to impossible to win the lottery, but someone does, and the fact that you couldn’t have predicted the winner beforehand (unfortunately) is just as much as a giveaway as the fact that you couldn’t have predicted the arrangement of grass blades on your golf ball after the drive.
  3. This brings us to the third point, which is that you couldn’t predict – and no computer simulations have done so, because the number of variables is far too large – what kind of universe you would end up with given any set of values for these universal constants. Even our own. So given a set of random values for the constants, we might possibly ‘end up with’ a universe, planet or life-forms that differ from our own, but who’s to say that a similar observation might not be made by the life-forms there, who might proclaim “Wow, this super weak charge on the electron is exactly what’s required for my kind of plasmoid energy-field life matrix.”
  4. There is also the sheer power of evolution to contend with when we come to alternative universes. Natural selection is a universal phenomenon, and it will operate in any situation where information can replicate itself, compete for population space, and pass on its characteristics (notably those that make it good at replicating itself). For life on Earth, that information is coded in the form of chains of atoms in DNA. Given a range of values for the universal constants, natural selection will operate to generate populations of replicators (that we may call ‘life’) that are better and better adapted to the niches in which the  individuals reside. Evolution will tailor life to fit the prevailing conditions, whatever they are, even in universes whose values for the constants might seem wildly exotic to us. Even in the presence of supercomputers that could work out the physics, this fact alone would mitigate against the possibility of predicting the kind of life that might arise.

I like to quote Douglas Adams when talking about the absurdity of the Anthropic Principle, especially in relation to the biological process that fits life to its environment:

Imagine a puddle waking up one morning and thinking, ‘This is an interesting world I find myself in, an interesting hole I find myself in, fits me rather neatly, doesn’t it? In fact it fits me staggeringly well, must have been made to have me in it!’ This is such a powerful idea that as the sun rises in the sky and the air heats up and as, gradually, the puddle gets smaller and smaller, it’s still frantically hanging on to the notion that everything’s going to be alright, because this world was meant to have him in it, was built to have him in it; so the moment he disappears catches him rather by surprise. I think this may be something we need to be on the watch out for.



October 18, 2009 Leave a comment

In the last few years, I’ve become increasingly fascinated with two issues that are related in a very strange manner. The first is evolutionary biology. Since reading Richard Dawkins’s The Blind Watchmaker a couple of decades ago, I’ve been intrigued at the simplicity and power of Darwin’s natural selection. Dennett reached fever pitch in Darwin’s Dangerous Idea, and ever since, I’ve been reading everything on the topic.

The second issue is creationism, and its big brother religion. I’m not religious myself, having learned early on the art of rational enquiry, but the way that creationism plays upon human cognitive biases is utterly fascinating. Hence I’m a regular reader of Pharyngula, and would someday like to see a completed human memome mapping, showing exactly how these ideas spread around human minds, and how they can be implanted and exploited by charlatans who would have you join their authoritarian organisations, or support them financially.

The truth, and “the truth”

August 26, 2009 Leave a comment

I’ve just come across a superb pair of quotes in the (largely appalling) reader comments beneath Richard Dawkins’s latest article in The Times Online (which is an extract from his forthcoming book). To quote first Bertrand Russell and then Richard Dawkins:

If I were to suggest that between the Earth and Mars there is a china teapot revolving about the sun in an elliptical orbit, nobody would be able to disprove my assertion provided I were careful to add that the teapot is too small to be revealed even by our most powerful telescopes. But if I were to go on to say that, since my assertion cannot be disproved, it is an intolerable presumption on the part of human reason to doubt it, I should rightly be thought to be talking nonsense. If, however, the existence of such a teapot were affirmed in ancient books, taught as the sacred truth every Sunday, and instilled into the minds of children at school, hesitation to believe in its existence would become a mark of eccentricity and entitle the doubter to the attentions of the psychiatrist in an enlightened age or of the Inquisitor in an earlier time.

Dawkins says:

The reason organized religion merits outright hostility is that, unlike belief in Russell’s teapot, religion is powerful, influential, tax-exempt and systematically passed on to children too young to defend themselves. Children are not compelled to spend their formative years memorizing loony books about teapots. Government-subsidized schools don’t exclude children whose parents prefer the wrong shape of teapot. Teapot-believers don’t stone teapot-unbelievers, teapot-apostates, teapot-heretics and teapot-blasphemers to death. Mothers don’t warn their sons off marrying teapot-shiksas whose parents believe in three teapots rather than one. People who put the milk in first don’t kneecap those who put the tea in first.

I thought that was worth recording. However, I still think Richard makes his same old mistake in this article when he says:

Influential philosophers tell us we can’t prove anything in science. Mathematicians can prove things — according to one strict view, they are the only people who can — but the best that scientists can do is fail to disprove things while pointing to how hard they tried. Even the undisputed theory that the Moon is smaller than the Sun cannot, to the satisfaction of a certain kind of philosopher, be proved in the way that, for example, the Pythagorean Theorem can be proved. But massive accretions of evidence support it so strongly that to deny it the status of “fact” seems ridiculous to all but pedants. The same is true of evolution. Evolution is a fact in the same sense as it is a fact that Paris is in the northern hemisphere. Though logic-choppers rule the town, some theories are beyond sensible doubt, and we call them facts. The more energetically and thoroughly you try to disprove a theory, if it survives the assault, the more closely it approaches what common sense happily calls a fact.

Once upon a time, as we well know, it was ridiculous to deny that the Sun and the stars went around the Earth, but enough evidence was then gained to overthrow that theory. The one theory that still stands – against any test – is that the Earth goes around the Sun. That’s doesn’t make it True. Giving it that label would be to say to future scientists who discover, maybe, that we are after all in a nine-dimensional universe where the notion of ‘orbiting around’ something is a quaintly naive one that should be remembered with a slightly embarrassed chuckle.

No, it makes that a theory – a bloody good one, that stands against all the tests we can throw at it, including all the evidence we can amass, and all the predictions we can make – but still a proposition that can fail at any time that we discover something that contradicts it.

And this is the proper nature of science: hold to the best theory until such time as it’s untenable, and then relent in the face of a better one. Now just because challenging evidence or a better theory has not come along for heliocentrism or evolution, or natural selection, it doesn’t mean that those theories are True – it just means what it’s supposed to mean: that they are the best yet. They are true with a small ‘t’.

That is incredibly important, and one of the only things that separates scientific statements from evangelical or faith-based ones. Scientists are always prepared to abandon a theory that is contradicted by clear and unambiguous evidence against it, and adopt a better theory, whereas faith adherents never are. Scientists are humble and honest.

What Richard is doing here is just appearing to be no different from some priest. I know he doesn’t mean to – and he knows it’s the last thing that a scientist should be doing – but nevertheless, he keeps baying that This is True, and That is True, and those statements are antithetical to an honest scientist’s humble standpoint. It is not just a matter of pedantry to insist that we get this right, because recognition of the types of claims that people make is absolutely central to their understanding their content.

We aren’t going to beat creationists by playing them at their own game, and shouting from raised towers with the biggest megaphone. Sure, we may get the attention of the public, and that’s certainly very important, as Richard himself admits when he says that it’s a ‘consciousness raising’ effort. People looking up at the towers will just think “Hey, those truth-heads are shouting at each other again!” and just ignore both of us, thinking that it’s just a battle for supremacy on some power scale. They don’t realise that the two approaches to knowledge are completely different, that the scales are not the same scale, and no wonder if both parties appear to be doing the same thing, whatever their intentions.

What will win the battle is for Richard to use downright honesty in how he helps people distinguish scientific claims from faith-based ones, and this notion of Truth is, I think, the only way to do it. He is clearly an honest and passionate man, but he’s unwittingly making himself look like his enemy, which is defeating his purpose of explaining why the kinds of answers that science gives are different from every other attempt to explain the natural world.

He even relented at the end there, saying that something ‘approaches’ a fact, and that’s the phraseology he must stick to if he wants to highlight the difference clearly and effectively.