Cosmology and telology have changed in this century as a result of relativity and quantum mechanics. Previously, classical physicists such as Newton saw both the universe itself, and the laws according to which it evolves, as being the work of a God who, as it were, wrote the rules, built the machine and set it running. Indeed many classical physicists regarded the search to understand the laws of the universe as a quest to discover God's master plan. Modern cosmologists, however, don't require a god or gods to create the universe: in their cosmology the universe itself - mass, time and space - all appear together in accordance with the laws of quantum mechanics. The largest role that modern physics leaves to a god or gods is that of deciding which laws the universe will obey, and this is the area into which teleology has moved.

Wallace, Hoyle, Dyson and others have made the point that even slight changes in some values of fundamental or cosmological constants, or even in the laws of physics themselves, would imply a universe in which life as we know it would not exist. Here are a few examples: If the universe were much less dense, then stars and planets might not form. If the universe were much more dense, then it would have stopped expanding and contracted back into a hot big crunch long ago, possibly before any supernovæ had had time to generate the elements needed for life. What if the laws of physics were different? If the strong nuclear force were much weaker than it is, then the electrostatic repulsion between protons would prevent the formation of large nuclei - hydrogen might be the only element. If gravity were different, or if the geometry of space-time were different, then stars might not form or planets might not have stable orbits.

Physicists usually ask: What are the laws of nature? But we also ask: why are the laws as they are? Could they have been otherwise? Is there anything inevitable or preordained about the actual laws of the universe? Stephen Hawking, in his popular book, "A Brief History of Time", poses these questions, but is somewhat equivocal in answering them. His casual line about the "Mind of God" seems to be a metaphor. (I wrote to find out, and enclosed the text of this article. The reply from the Lucasian Professor of Mathematics was brief: "I agree, Stephen Hawking"). The use of the word God as a metaphor for the laws of physics has a distinguished history: Einstein used the famous phrase "God does not play dice" as his way of saying "The universe is not probabilistic".

Paul Davies goes further than this: he sees a (quote)"sort of purpose in the universe" and argues that conscious, intelligent beings are somehow (quote)"central to the universe" - that the laws of physics are the way they are in order that consciousness and intelligence may develop.

This is the point that I want to dispute. I shan't argue about whether there is or isn't a divine legislator, or whether the universe is purposeful, and I shan't express a view on the origin of the laws of physics. In this talk I shall only point out the logical fallacy in teleological cosmology - the flaw in the argument for purpose in the universe.

I first wondered about purpose and contingency in the universe when I was about seven, following a discussion with my grandmother. Grandma didn't mention cosmology: rather she told me the story of the circumstances that took her from her native Denmark to settle in Australia. (I found out later that she embellished the account enormously for dramatic effect but that's another story.) What set me thinking was the marvellous observation that if she hadn't come all the way from Denmark, or if grand-dad hadn't come from Germany, or if any of my various ancestors had made slightly different decisions, I would not be here. The idea that we might not have been here is something that I suppose everybody wonders about - it's one of the capital B.Q. Big Questions. So, at an early age, I marvelled at the chain of very slim probabilities which had led to my existence.

Nevertheless, in spite of this marvel, I was never quite so egocentric as to imagine that my various ancestors had all decided to leave their various homelands and migrate to Australia just so that they could meet and have kids who would meet and have me!

You see, even as a seven year old I think that I understood something important about probability: it changes when the event happens. Let me explain by example: the probability that the next coin I toss will be heads is 50 percent. The probability that the last one I tossed was heads is (as it happens) zero - no calculation or theory is necessary: I can see the platypus and not Ms. Windsor. I toss it twenty times and get t,t,h,h,h,t,t,t,h,t,h,t,t,t,h,h,t,t,h,t. The chances of that particular sequence were about one in a million before I did it, but now it has happened and the probability is one. If I had tossed them differently, then I could have produced a different series, also with a prior probability of one in a million.

If the conditions of the early universe had been such that stars never condensed, or if the strong force didn't exist and the periodic table had only one entry, or if anything else had been slightly different, then we wouldn't be here - whatever "here" might mean in such a context. But it makes little sense to talk about the universe being improbable after the event. The conditional probability of the universe being as it is, given the existence of these particular human cosmologists to marvel at it, that conditional probability is either exactly one or very very close.

I hope the parallels with coin tossing are obvious: the chances of any one particular head-tail sequence is small, and if I toss 20 coins again there is only a one-in-a-million chance that I would get the same series again. But this does not make the first sequence profoundly special: it is special only in the sense that it is the one that happened. Analogously, if we were somehow to start cosmic history over again from a big bang, the chances that we would get the same phenomena or objects, or even phenomena or objects of the same sort, may be very small. But does that make the universe special? The universe does have planets, chemistry, life and us: it is special in the sense that it has us in it, but that of course is a given in this problem because we are here talking about it.

Now I can foresee an objection from the teleologists. They might say "well what if your twenty coin tosses had been all heads? Wouldn't you then be surprised? Wouldn't you then look to see if someone had fixed the coin?" Well the answers are "yes" and "yes". But a sequence of heads is not a good analogy to a universe which contains us. There is a way of defining something that is at least subjectively special about a sequence of all heads, using the concept of algorithmic entropy developed by Kolmogorov and Chaikin. Essentially it says that some sequences are simpler than others because an algorithm exists for reproducing them from a smaller quantity of information.

But what is comparably simple about the universe? In what way is the universe special? The teleologists would say that it is special because it allows planets, life, intelligence (and even cosmology) to exist. But that is not a small conditional probability: there is nothing improbable about that given that we - planet-based, intelligent life-forms - are here. If the universe were different then something else would be here - that something might not include planets, life or intelligence as we know it.

This position is close to what is called the weak anthropic principle. Stephen Hawking puts it nicely in his book. "Intelligent beings" he says, "should not be surprised if they observe that their locality in the universe satisfies the conditions that are necessary for their existence". He's right of course. But the anthropic principle can, with the same logic, be applied to the laws of physics themselves. One can equally state that: "Intelligent beings should not be surprised if the laws of physics are consistent with the existence of intelligent beings".

It is occasionally alleged that the anthropic principle "explains" the nature of the universe. We exist, and for us to exist the universe must be as it is, and our existence is said, by some, to "explain" the nature of the universe. In fairness it should be said that this strong version of the anthropic principle is perhaps more often raised as a straw man by its opponents who then proceed to knock it down. But if the anthropic principle is said to be an "explanation", it is not an explanation in the usual sense in which scientists use the word. My grandparent analogy is helpful here: if my grandmother had not come to Australia I would not exist, but my existence does not explain why she came to Australia - or at least it is not an explanation in the usual sense. (As to the actual explanation of her migration, I'm not sure which of my grandma's stories to believe on this, but I'm certain that she did not say: "I'll go to Australia so that I can meet Ferdinand and marry him and give birth to May who will marry Jim and produce Joe".)

So let's get back to teleological cosmology: here is what Paul Davies said at the ABC Science lunch earlier this year: "The laws of physics didn't have to be as they are - they could have been otherwise. .... there's no logical compulsion why things have to be the way they are. So this inevitably begs the question: is there anything special about the actual laws of the universe?" Davies continues; "Well the answer is yes: far from being any old ragbag of laws, the actual laws seem to be remarkably ingenious - one might even say contrived in their particular form. Not only do the laws permit a universe to come into being spontaneously - as it were create itself - they also permit it to be self organising." Davies then goes on to argue that "the universe as a whole displays a sort of purpose", that "Consciousness is a fundamental rather than an incidental feature of the universe" and that we (i.e. conscious beings) "are central, not incidental to the universe". Well I agree with him about one thing: his argument begs the question. If the laws of physics did not allow the universe to come into existence, or if they did not allow any of the organisation that is essential to life, he would not be here to comment on how contrived those very laws were, or to argue that those laws must have been chosen so as to allow a universe to exist and to contain a conscious being such as himself.

The history of cosmology seems to be a story of humans conquering our vanity: cosmologists in the Western tradition had to discover that the Mediterranean was not the centre of the world, that the world was not the centre of the solar system, and that the sun was not the centre of the galaxy nor the galaxy the centre of the universe. This planet, this sun and this galaxy are all special - for us - in that they support us and that we, being here, observe them. They are not particularly special in any other way. The laws of nature are special in the same sense - that they support us and that we, being here, can observe them. They are not particularly special in any other way.

Teleology is not new of course: Alfred Wallace presented a cosmological version of it in 1903. Nor is my objection new: 200 years ago, Emanuel Kant argued in a similar way to show the falsity of the telological argument for creation, and Voltaire gave the Panglosses of the world a hard time in his book "Candide". So today it's unnecessary to refute the speculation that the Universe was created like this deliberately so that intelligent life could develop. I have just used similar logic to show the flaw in the argument that the laws of the Universe were somehow deliberately legislated in order to allow, or even to oblige, life and consciousness to develop.

Still, as it seems that there are cosmologists who seriously propose this position, I'd be interested to hear whether they have similarly egocentric views on the actions of their grandmothers.