The Weak Anthropic Principle

On Youtube, videos can be found of a lively debate between religious people (usually Christians) and atheists about philosophical questions. What is interesting about these disputes is the degree of civility among the participants – the Christians, in particular, seem quite willing to engage with the atheists without taking offence. You would think that, feeling that their core beliefs are under attack, the Christians would become upset, defensive, but it seems that their faith is not so fragile that it can be damaged, undone, by an onslaught of materialist rationality. The atheists (and here I'm thinking of the Four Horseman – Sam Harris, Daniel Dennett, Richard Dawkins, and the late Christopher Hitchens) seem more intolerant than their religiously minded interlocutors and more intent on conversion. The Christians never imply that their adversaries are stupid but the atheists often do. In tonight's post I wish to describe and comment on a particular back-and-forth debate that I have seen played out on Youtube between the theists and the atheists. The Christians propose that the universe is so finely tuned for life (and hence for intelligent moral life) that it must have been designed by an intelligent creator; the atheists counter this argument by saying that the appearance of fine-tuning is unsurprising given 'the weak anthropic principle'. To this, the Christians respond with a wonderful argument (an argument that I had never heard until this week) analogising our finding ourselves in a world that seems so suited to intelligent life to the situation of a person who survives unscathed being fired on by a firing squad. The Christians conclude that the weak anthropic principle explains nothing, is a kind of abdication of rationality. In tonight's post, I wish to describe these three arguments in more detail and say something about them. Being a sort of agnostic, I don't have a horse in this race. I hope, though, that in writing this post, I can clarify my own thoughts about these ideas.

We begin with the 'fine-tuning argument'. Physicists have shown that the universe, physical reality, depends on certain physical constants, such as the speed of light in a vacuum, the charge-to-mass ratio of electrons, and Planck's constant. It is proposed that if any of these constants were only slightly different, the universe as we know it wouldn't exist, and therefore we wouldn't be around to determine the values of all these constants. Three possible explanations are put forward to account for this puzzling fact. The first is that, for reasons we currently do not understand, the constants could not have taken any values other than the ones they do. The second is that these constants have the values they do because of pure, blind chance. The third is that an intelligent designer picked these constants because He (or She) knew that eventually the universe would bring forth sentient, moral agents who would sing His (or Her) praises in church every Sunday. The atheists waver between the first two explanations while the Christians, unsurprisingly, opt for the third. To me, it seems that the first two explanations could be regarded as equivalent. Consider pi. Euler and others have shown that pi could not take any value other than the one it does, at least in our universe. But we can imagine a simulation inhabited by 'organisms' the are born, move around, reproduce and die that takes the form of a curved two-dimensional surface. These organisms would measure the value of pi differently than those of us who live in flat space-time. It seems to me that both explanations beg the question: why? Why are the laws of physics in our universe such that they can support intelligent life? The Christians, with an unmistakable air of triumph, assert that the extraordinarily unlikelihood of the constants all being such that our universe can support sentient beings is evidence of an intelligent Creator. (Although this begs the question: Why a Creator? Why anything at all?)

The atheists respond to this rather robust challenge by citing the 'anthropic principle'. There are two versions of the anthropic principle, the strong principle and the weak principle. The strong principle states that somehow the universe is compelled to produce intelligent life. The strong version of the principle smells like religion to me and may well smell like religion to atheists because they seldom endorse the strong principle, picking the weak principle instead. To put it simply, the weak anthropic principle states, "The universe is the way it is because otherwise we would not be here to observe it." The weak anthropic principle can be understood most readily if we suppose a multiverse. If we postulate that there are an infinite number of universes all with different values of the various constants, it is no longer surprising that we find ourselves in a universe capable of supporting intelligent life. At least one of them had to and we were just lucky enough to find ourselves in one of them that does. But I don't think we need to postulate a multiverse to entertain the idea of the anthropic principle. Consider the following analogy. Suppose, dear reader, you go out today and buy a lottery ticket with a one in a million chance of winning a million dollars and you know that ten million others have also bought a ticket. You might tell yourself, "Well, someone has to win. Why not me?" (I'm sure all prospective lottery winners rationalise their purchase in the same way.) Perhaps you will, therefore, be unsurprised if you do win. But now suppose that you were the only one to buy a ticket – and you win. You might be very surprised indeed. But, in either case, the probability of you in particular winning was the same, one in a million. This suggests that the idea of a multiverse is unnecessary when considering the anthropic principle.

The anthropic principle is popular among atheists as a way of criticising the fine-tuning argument. In The God Delusion, for instance, Richard Dawkins employs this argument in much the same way as I did in the previous paragraph. Enter, playing for the Christian team, John A. Leslie (although, to be accurate, Leslie is a Pantheist rather than a Christian.) Leslie offers the following parable, which I shall quote from the site Hyperphysics. "In this parable, an individual faces a firing squad, and fifty expert marksmen aim their rifles to carry out the deed. The order is given, the shots ring out, and yet somehow all the bullets miss and the condemned individual walks away unscathed." It seems that the individual should be surprised to be still alive. The individual herself, and any disinterested observers, would be forced to ask themselves a question: Which is more plausible, that all the marksmen missed by accident, in a random fluke, or that they all missed on purpose, by design? This argument is so strong that even Dawkins has admitted as much, that it is a compelling argument, in an interview post publication of The God Delusion.

Suppose however that the individual is a fan of the anthropic principle. She might say to the puzzled observers, "Of course they all missed! Otherwise I wouldn't be here to notice the fact!" But this strikes me, as I said in the introduction, to be an abdication of scientific responsibility, the responsibility to try to explain puzzling phenomena. Atheists often berate religious people for espousing the god-of-the-gaps fallacy, the idea that anything we don't understand about the world can be explained by a divine being who designed, for instance, the flagella of amoeba, that such gaps in scientific knowledge in fact prove the existence of God. It seems to me though that saying that anything we don't understand is the result of blind chance is a similar type of fallacy. Charles Darwin, famously, found the plumage of peacocks physically nauseating. This historical detail is mentioned by Michele Hewitson (I think) in a recent column in The Listener – Hewitson states that Darwin found the tails of peacocks nauseating because it went against his theory of 'survival of the fittest'. I have read elsewhere that the reason Darwin offered for the plumage of peacocks is sexual selection and that the reason he found peacock tails nauseating was a kind of puritanical disgust, was because they reminded him of the depraved licentiousness of all living beings. The meaning of life, according to evolutionists, is only survival and reproduction, and it was this 'truth' that Darwin had discovered that made him ill. Nevertheless, despite Darwin's promotion of the idea of 'sexual selection', peacocks' tails have proved notoriously difficult for evolutionary biologists to adequately explain. Religious people might say, "The reason peacocks have such beautiful feathers is that this is way God designed them." The atheists might respond, "The reason peacocks have such beautiful feathers is blind chance, an extremely unlikely fluke of nature." If an atheist has the anthropic principle in mind, she might say, "Of course, male peacocks have beautiful feathers. If they didn't, they wouldn't be here for us to see." None of these putative explanations explain anything. The plumage of peacocks demands explanation, either through applying evolutionary theory or postulating an alternative theory. Unusual events, and even usual events, require explanation, and this is the role of science and scientists. A second problem with the anthropic principle, it seems to me, is that it puts the effect before the cause. "The reason the universe is the way it is is because eventually it would bring forth intelligent beings who would study it." However, to explain something about the universe, we need to either go back in time to prior causes or discover something more fundamental about the universe, something which explains both the values of the constants and the eventual appearance of sentient life. For these reasons, I find the weak anthropic principle unsatisfactory – although I do not have the foggiest idea of what a better explanation would look like.

This has been a shorter post than many I have written recently. I do not think I have expressed my thoughts about the weak anthropic principle as clearly as it deserves but I hope that this post has stimulated my readers to think about the issues that arise from it themselves and to come to their own conclusions. I wish to point my readers to some other posts I have written, the two posts about quantum physics ("Probability and Schrondinger's Cat, Part 1" and "Probability and Schrondinger's Cat Part 2") – I think these two posts are probably the most profound I have published in this blog. Before I say adios for tonight, I wish to say something about the previous post. Although it was very critical of the psychologist I saw in 2014, I believe it was a very important post, an important statement, because, although anecdotal, it may speak to a deeper truth, that many other patients of Mental Health Services here and overseas have been grossly mistreated by those whose jobs are to help. I have noticed the blog has had fewer hits than it usually receives over the last week and hope that it hasn't somehow been blocked. If I have regular readers, I hope that you are still interested. Thanks, anyway, to those taking an interest.