A favourite and fashionable argument for God is the argument from a fine-tuned universe. The argument is that, were it not for many aspects of our universe being “just right” for us to exist, then we wouldn’t be here, therefore [and that "therefore" is the big leap] the universe must have been fine-tuned to produce us.
Such an argument is advanced by theologians such as Alvin Plantinga and William Lane Craig, while Francis Collins has even gone so far as to claim that Richard Dawkins has admitted that he is troubled by the argument (this led to a witty response by Dawkins).
However, this argument is not just flawed, it actually contains six major flaws. The argument is one of those that is so unconvincing that it never leads anyone to believe in God, it only bolsters the faith of those who already believe, in which state their credulity renders them unable to examine the argument objectively.
The essence of the flaw is that the argument depends on regarding humans as “special”, as though a universe without humans would be improper in some way. Thus the argument is simply anthropocentric hubris, and takes as an axiom (the specialness of humans) what it aims to prove (the specialness of God-created humans).
Yes, we may be special to ourselves, but that doesn’t mean we matter especially to the universe. Theists often err by assuming that what matters to humans must matter in an absolute or universal sense. And without that “specialness” assumption the argument from fine tuning falls apart.
Entities that are peculiar to and characteristic of their environment are exactly what you would expect from non-intelligent, natural processes. Intelligent design could produce either outcome: inhabitants that are well-fitted to their environment or inhabitants that are not (as in zoos). Non-intelligent processes could only produce the former. Thus, the fact that the universe appears to be “fine tuned” to produce its inhabitants is a direct prediction of atheism, but not of theism. Thus the fine-tuning argument actually argues for an atheistic universe.
So here is a reasonably succinct summary of those six flaws, in reply to the theologians.
(1) Who says the universe is tuned for life? As far as we know, intelligent life occurs in only one million-billion-billion-billionth of the universe around us. It’s not the case that the universe is teeming with life, is it? If someone intelligent were going to design a universe to host life, they could do it a heck of a lot more parsimoniously than by inventing our universe.
Tell you what, pick a random cubic kilometre of our universe; now try making a case for theism given only the contents of that cube. If you object that you want instead a highly particular, specially chosen chunk of universe (Earth) on which to base your case, then that’s anthropocentric special pleading. If your case had merit it could still be made without carefully selecting your data inputs. Afterall, without Earth, you’d still have 99.999999999999% of God’s creation to work with.
(2) So what if the universe were different? Yes, it wouldn’t be as we know it, and wouldn’t produce the sort of life forms that we know, but do you really know that it wouldn’t produce just as much or more life as our universe? Do you really think you know enough about the various possible types of life, and about the consequences of fiddling with fundamental constants, to work that out? We have a hard enough time figuring out and understanding our own universe, even though it is right here under our noses available for study.
(3) Of course the universe is “just perfect” for producing us. In the same way — and here Douglas Adams’s analogy is unsurpassed — a puddle thinks that the shape of the hole in the road is just perfect for producing its own shape. “Only if the hole were exactly as it is in every detail could my shape have come about! So clearly an Intelligent Designer must have carefully designed that hole in exquisite detail in order to produce me!”
Isn’t it obvious that the things that come to be in a universe will be things that are highly characteristic of that universe? Things fitting exactly to their environment is exactly what you expect in a NON-intelligent situation — in the same way that puddles of water fitting their hole is the obvious consequence of a non-intelligent process like gravity.
(3b) The occurrence of things for which their environment was NOT “just right” would be a far better indicator of intelligent intervention. For example, an animal in a zoo is indicative of intelligent intervention; an animal that fits perfectly into its ecological niche is not an indication of intelligent design, but instead is amply explained by non-intelligent processes such as evolution. Thus, if we found ourselves in a universe that was not suited to creating us then that would be far better evidence for intelligent intervention!
(4) If the universe is one of myriad different universes, then intelligent life will only appear in those suitable for intelligent life. So the act of an intelligent life-form asking “why is the universe like it is?” will pick out those universes, even if they are a tiny, tiny faction of the total collection of universes. If there were 101000 universes then there needn’t be anything special about parameters that lead to life in order for there to be sentient life-forms asking that question, somewhere.
For comparison, life as we know it can only exist on planets in the “habitable zone” range of distances from a star. Yet we don’t say that some intelligent agent must have ensured that Earth-like planets are only placed within that zone. Instead, we now know that planets are abundant around stars, and that these planets are strewn around with a whole range of distances. Thus some fraction end up, by chance not design, in the habitable zone.
(5) Even if the universe were a one-off, so what? The things present in that universe would still be specific to that universe. In the same way, if you throw one dice a thousand times you create a highly improbable number (with a likelihood of only 1-in-61000, which is 1-in-10778). Would you argue that the universe had to have been fine-tuned to produce the number you’ve just got? Nope, there could simply have been some other number. The outcome would only be remarkable if there was something special about that number.
So do you want to claim as an axiom that there is something special about intelligent life? You need to claim that, but if you do you’ve created an entirely circular argument. You start off with the axiom that there is something special about intelligent life — and guess what, you end up with the conclusion that the universe possesses the special property of intelligence (which you want to be the creator you are hankering after). But you’ve just assumed your conclusion in your axiom! Try repeating the argument without making any assumption that intelligent life is special — then you’d get nowhere.
(6) And above all: your “creator” explanation gets you nowhere! It explains nothing. All it lands you with is something even harder to explain, even more remarkable, even more improbable. And trying to pretend that your creator god is not, actually, all that remarkable and doesn’t, actually, need an explanation, is a preposterous evasion.