The God Delusion

The anthropic principle is impotent to explain the multifarious details of living creatures. We really need Darwin’s powerful crane to account for the diversity of life on Earth, and especially the persuasive illusion of design. The origin of life, by contrast, lies outside the reach of that crane, because natural selection cannot proceed without it. Here the anthropic principle comes into its own. We can deal with the unique origin of life by postulating a very large number of planetary opportunities. Once that initial stroke of luck has been granted – and the anthropic principle most decisively grants it to us – natural selection takes over: and natural selection is emphatically not a matter of luck.

An intriguing version of the multiverse theory arises out of considerations of the ultimate fate of our universe. Depending upon the values of numbers such as Martin Rees’s six constants, our universe may be destined to expand indefinitely, or it may stabilise at an equilibrium, or the expansion may reverse itself and go into contraction, culminating in the so-called ‘big crunch’ Some big crunch models have the universe then bouncing back into expansion, and so on indefinitely with, say, a 20-billion-year cycle time. The standard model of our universe says that time itself began in the big bang, along with space, some 13 billion years ago. The serial big crunch model would amend that statement: our time and space did indeed begin in our big bang, but this was just the latest in a long series of big bangs, each one initiated by the big crunch that terminated the previous universe in the series. Nobody understands what goes on in singularities such as the big bang, so it is conceivable that the laws and constants are reset to new values, each time. If bang-expansion-contraction-crunch cycles have been going on for ever like a cosmic accordion, we have a serial, rather than a parallel, version of the multiverse. Once again, the anthropic principle does its explanatory duty. Of all the universes in the series, only a minority have their ‘dials’ tuned to biogenic conditions. And, of course, the present universe has to be one of that minority, because we are in it. As it turns out, this serial version of the multiverse must now be judged less likely than it once was, because recent evidence is starting to steer us away from the big crunch model. It now looks as though our own universe is destined to expand for ever.

Maybe scientists are fundamentalist when it comes to defining in some abstract way what is meant by ‘truth’. But so is everybody else. I am no more fundamentalist when I say evolution is true than when I say it is true that New Zealand is in the southern hemisphere. We believe in evolution because the evidence supports it, and we would abandon it overnight if new evidence arose to disprove it. No real fundamentalist would ever say anything like that.

It is all too easy to confuse fundamentalism with passion. I may well appear passionate when I defend evolution against a fundamentalist creationist, but this is not because of a rival fundamentalism of my own. It is because the evidence for evolution is overwhelmingly strong and I am passionately distressed that my opponent can’t see it – or, more usually, refuses to look at it because it contradicts his holy book. My passion is increased when I think about how much the poor fundamentalists, and those whom they influence, are missing. The truths of evolution, along with many other scientific truths, are so engrossingly fascinating and beautiful; how truly tragic to die having missed out on all that! Of course that makes me passionate. How could it not? But my belief in evolution is not fundamentalism, and it is not faith, because I know what it would take to change my mind, and I would gladly do so if the necessary evidence were forthcoming.