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The Anthropic Fallacy

December 1, 2009 Leave a comment Go to 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.

  1. December 1, 2009 at 8:54 pm

    1) You don’t have a clue how to apply the goldilocks enigma.


    2) Chance/probabilities have absolutely nothing to do with the anthropic principle until you bail out on the first principles that are expected by physicists to resolve the problem.

    3) Same answer, fool.

    4) So where is life on Mars or Venus? Again, you have no clue how to apply the goldilocks enigma.

    THIS is the anthropic principle, oh willfully ignorant one.


    • December 2, 2009 at 11:28 am

      Well now, I may be ignorant – what honest person can say they are not, but I couldn’t imagine that I’m wilfully ignorant. I’ve tried very hard to understand the things you’ve written, both here and on your website, and I can honestly say that I cannot get head nor tail of it, try as I might.

      I can’t even say whether I think you’re wrong or not, because I simply can’t grasp what you’re trying to say. I mean, I understand all the terms you’re using perfectly well, but I can’t see that there’s a well-structured argument in there anywhere, at least not one much to do with what I’ve written.

      If you want to be understood more easily, you might want to (a) consider writing more clearly, with less emphasis on trying to make yourself sound authoritative or clever, and (b) trying a little harder not to be quite so rude. It’s clear that you’re passionately interested in the theories you expound, but you might stand more chance of getting your theories accepted, and getting people to listen to you, if you can control your emotions a little better.

      Now having said that, it might well be true that the universe’s physics lead naturally to carbon-based life (if that’s what you’re actually claiming – as I say, it’s hard to tell) and I see no reason to argue with that. It might well be true, and we have at least one instance of this being the case.

      It might even be the case that any set of values for the universal constants would ‘tune’ themselves towards the kind of physics we see today, so that complex carbon molecules are more likely than chance might suggest from the infinite variation possible in those constants. Who knows.

      But the fascination most people have about the anthropic principle makes them think that there’s something ‘spooky’ or ‘suspicious’ about this – that the universe somehow had us planned when it started out, which is the nonsense I’ve tried to dispel. If you’ve got a different definition of the principle, then that’s not the one I’m arguing with: I’m looking solely at people’s attraction to this illusion that we’re special.

      Some people go even further and try to suggest that the cause-and-effect we think we see is actually the wrong way around, and that it’s our minds that create the universe around us, in some hugely out-of-context application of the mysteries of quantum mechanics.

      Also, while I think of it, just because a theory has not yet been overturned, that is no indication of its validity, especially if there are no tests that could be performed to test the theory. Theories only become properly scientific when they have survived many assaults by practical experimentation and prediction, and been supported by the available evidence.

      For example, you can’t disprove Bertrand Russell’s theory that there is a teapot in orbit around the Sun. That doesn’t mean that the theory is sound, or scientific, however, because it could never be practicably tested, or thence falsified.

  2. December 15, 2009 at 3:57 pm

    Heh – I notice that this guy is banned from a number of high-profile scientific sites for being a crank. His alter ego is ‘island’, which I think says a lot about him.

    Meanwhile, I link to this excellent cartoon:


  3. O. King
    October 21, 2010 at 9:57 pm

    Bravo, Christopher Gray. A succint, clear and legitimate exposition of the Anthropic Principle. I intend to give a presentation on the Anthropic Principle under the name The Goldilocks Fallacy (the postulation of the ‘just-rightness’ of physical conditions in retrospect of the fact that these conditions engendered us); our arguments are virtually the same.

    Concerning this Ricky, what planet is he from?

  4. October 25, 2010 at 8:58 am

    Thanks, O. King.

    It’s been interesting, during the last year, to see what progress has been made in understanding the origins of our universe, and the laws which seem to govern it. The work of the Perimeter Institute, where such luminaries as Neil Turok are shining a light onto Big Bang alternatives, is particularly fascinating. I notice also that there’s an ongoing debate as to whether the Fine Structure Constant is, in fact, not a constant.

    Wherever we look, we find that things are not quite as they appear to our somewhat simple minds that are used to grasping only the most basic concepts. If anything, that represents another nail in the coffin of the Anthropic Principle: how can we expect to understand the past if we can’t even correctly interpret the present.

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