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An Atheist Defends the Design Argument

This article is about the design argument. The original argument, formulated most famously by Archdeacon Paley back in 1803[1], says simply that the world around us–specifically, the apparent design features we observe in living organisms–have all the hallmarks of intelligent design, and that this design is best explained by attributing them to the work of a Designer, namely, we might go on to say, “God.”

Of course, the theistic conclusion of this argument has been made a lot less intuitively plausible since the development of a well-confirmed naturalistic alternative, namely the Darwinian theory of evolution by natural selection. But the trends of philosophical fashion are rarely so simple. Just as one set of scientific developments has been seen as undermining an argument for God’s existence, another set of developments has opened up a rich new seam of possibilities. The design argument has shifted ground without abandoning its basic principle. This shift has given rise to a new variant of the design argument, which I will refer to as the fine-tuning argument.

In this article, I will argue that the reasoning that underpins the fine-tuning argument is far more robust than it is usually given credit for. To do this, I intend to defend the argument against a few very common objections.

I should probably clarify two points before I go any further. The first is that I’ve picked on one particular article–a post by Nathan Urban from the talk.origins archive–as a kind of ‘spokesperson’ for the objections I intend to criticise. Perhaps this is unfair, in which case I apologise to Nathan. But I ought to make clear that the objections I want to examine have been put forward by many different people, both philosophers and scientists, from across the whole spectrum of religious belief. And I’ve chosen that particular talk.origins post for three reasons:

  1. It goes through all the various objections in one short article.
  2. It’s a well thought-out, articulate and readable exposition of the position.
  3. Most importantly, it’s freely available on the internet[2], so readers can just surf over there and see what all the fuss is about.

My second point is that I’ve nailed my colours to the mast rather obviously in the title of this paper. I don’t believe in God. It follows, then, that although I think the fine-tuning argument is very strong, at the end of the day I don’t think it points to the conclusion that God exists. My aim in this article is neither to defend a theistic conclusion to the fine-tuning argument, nor to demolish it. My aim is rather to demonstrate that many of the usual attempts at demolition are simply inadequate, but a theistic conclusion is nevertheless unjustified.

The fine-tuning argument

The empirical premises for ‘fine-tuning’ have been passed over from scientists investigating what the cosmologist Sir Martin Rees[3] calls the “deep forces that shape the universe.” These forces boil down to six factors which were determined at the birth of the universe. Roughly speaking, they are:

  1. The strength of gravity.
  2. The strength of the force that binds atomic nuclei together.
  3. The amount of material in the universe.
  4. The strength of cosmic ‘antigravity.’
  5. The amount of irregularity in the distribution of mass in the early stages of the universe
  6. The number of spatial dimensions.

Other writers have come up with different summaries of these ‘fine-tuned’ factors. For instance, John Leslie, in his book Universes[4], lists many different factors, and Max Tegmark[5] pointed to the number of dimensions (three spatial, one temporal) as another factor that makes our universe uniquely conducive to the development of life.

The precise, measured values of these factors make our universe what it is. If any one of them was even a tiny bit different–if, say, gravity was a tiny bit stronger, or if there was very slightly less material in the universe–the universe wouldn’t be the way it is. This is what scientists mean when they say that the universe looks ‘fine-tuned.’ In fact, “these six numbers constitute a ‘recipe’ for a universe. Moreover, the outcome is sensitive to their values: if any of them were to be ‘untuned,’ there would be no stars and no life.”[6]

This is the observation that is significant to the fine-tuning argument: without each of these key values being exactly the way it is, there would be no stars, no galaxies, and certainly no life. In other words, there are many, many ways the universe could have been, but only an infinitesimally small number of those–“one in many billions of billions”[4]–would have resulted in a universe that contains life.

Based on this observation, we might sketch the fine-tuning argument as follows:

The universe is such that it produces and supports conscious life. Scientists believe that a universe could only do this if it was set up in a particular and very precise way. Out of all the possible ways that the universe could have been set up, the likelihood of its being life-containing is very small indeed, so we should not attribute this to chance. We should look for a better explanation, namely that there is a purposive agent who designed it that way.

This formulation will need a little refining in the light of the following objections, but I will argue that, taking into account these minor refinements, the argument will successfully overcome these objections.

If things were different, we wouldn’t be here

Even if this universe is wildly improbable, so what? By the anthropic principle, if it were different we wouldn’t be here to wonder about it.

This objection comes up very often, but when you think about it, it’s rather an odd response to the fine-tuning argument. Suppose a soldier is sentenced to death by firing squad, but when the order comes, all twelve of the marksmen inexplicably miss their target and the soldier survives. Now, for one of the marksmen to miss would be unlikely, but all twelve? The odds against it are huge, unless there’s been some deliberate tampering–bribery, sabotage, whatever. Surely the soldier is quite within his rights to wonder why the marksmen missed, and to try and find an answer to that question, even though–if they hadn’t–he wouldn’t be alive to wonder about it. He would be making a mistake if he just thought, “Oh well, that’s that, no explanation needed!”–and then went on his merry way.

Of course, it’s true that, if the universe weren’t life-permitting, we wouldn’t be here to wonder about it. But we know the universe is life-permitting, because here we are. The fact that we exist doesn’t somehow answer the question of why we exist, or make that question disappear; it doesn’t explain why the universe is like it is. Our existence didn’t somehow cause the universe to be life-permitting. The point of the fine-tuning argument is that, on the contrary, the universe could very easily have turned out differently, and then we’d never have existed. So we’re quite entitled to ask why we do exist.

This objection arises because of a misapplication of the anthropic principle. Basically, this principle makes the obvious point that we can only expect to find observers where conditions allow observers to exist. For instance:

If only one out of a trillion universes gave rise to life, then there would be 999,999,999,999 empty universes and one with beings saying ‘wow, what a coincidence!’ even though it was completely due to chance.

This is a valid point. If there are many universes, then we shouldn’t be surprised to find ourselves in a life-permitting one. But, if there’s only one universe, the anthropic principle has nothing to say about the probability of that universe being life-permitting. It certainly doesn’t stop us from asking ‘Why?’

Maybe things had to turn out this way

Sure, the parameters are ‘fine-tuned’ to produce life, but who says that the parameters could have taken on any other values in the first place? If you’re going to say that it’s ‘improbable’ that such a universe could have arisen, you must presuppose that the universe could have evolved some other way, but we have no information whatsoever on how, if at all, that may have occurred. It could be a law of physics that the constants can only take on the values that they do, for all we know!

True, we have to admit that we can’t have any scientific knowledge of what things were like before the key parameters of the universe were determined, so it’s impossible for us to judge the likelihood of these parameters turning out in any one particular way. But this fact doesn’t get rid of the need for an explanation other than chance for the way things are.

Suppose it was very likely or even completely certain that the universe would turn out fine-tuned for life, because the parameters were interrelated, or some prior law forced them down that road. Surely, then, the question is even more pressing: Why should this be so? What was it about the way things were before the birth of the universe that made a ‘fine-tuned’ universe so likely; what was it that ‘biased’ the universe in favour of life? If not a Designer, then it was some fact, law, force or circumstance. But then, we have to ask, why should there be that particular fact, law, force or circumstance, rather than any of the infinite number of other logically possible ones?

Whatever state of affairs we use to explain why the universe is so remarkably ‘fine-tuned,’ the question can always be put: why should there be that state of affairs rather than any other? Yes, it might conceivably have been physically impossible for the universe to turn out non-life-permitting, given some physical restriction on its parameters. But then the existence of that physical restriction needs explaining because it is the kind of physical restriction that makes life very likely or inevitable–and why should that be the case?

So the need for explanation wouldn’t be alleviated if we (somehow) learned that the universe was biased towards life even before the key parameters were set. That would just set the bias further back in time.

We’d draw the same conclusion whether or not the universe really was designed

Suppose hypothetically that the parameters of the universe were determined purely at random by some natural physical process (without intelligent design being involved), such as a quantum fluctuation or something. Further suppose that there are 10 such parameters, which can take on values between 1 and 6, with every permutation being equally likely. And finally suppose that the only configuration of parameters capable of giving rise to a universe with intelligent life is 3526525514, and that the universe happens to, by random, come up with that configuration. To us, those parameters are a meaningless and random sequence, no more and no less likely than any other. But to them, it’s an extremely special, unique, and very improbably “fine-tuned”–the odds are worse than 60 million to one!–set of parameters. But it would be incorrect for them to conclude that their universe was intelligently designed, because in this hypothetical example, it wasn’t!

But the fine-tuning argument never set out to be a proof. It’s no objection to a probabilistic argument to say that it doesn’t prove its conclusion. The argument only says that, given certain considerations, we should think it very likely that the universe was designed to be life-permitting. It doesn’t say that anything we’ve seen makes that conclusion absolutely certain.

So, if the universe wasn’t designed, we have to admit that it would still be possible (though very unlikely) for it to turn out just the way it has turned out. In that case, we, as ignorant life-forms, would still be justified in thinking that it probably was designed, but we would have been unfortunately misled by the evidence available to us.

Consider the casino analogy again. It’s (just) possible that your opponent is being completely honest, the die is completely fair, and he just happens to come up with the sequence of numbers (say, ten 6s) that allow him to win a fortune. If that were the case, then you, as an observer, would be misled by the evidence. You would be justified in thinking it very likely that the die was weighted, but in fact you’d be wrong. That doesn’t make your conclusion any less rational.[7]

Any outcome is equally improbable

It’s like rolling a die ten times and getting 3526525514 and saying “wow, the odds on that were 60 million to one, what a coincidence!” (And note that rolling 6666666666 is no less likely; the probability of getting 3526525514 is exactly the same as the probability of getting 6666666666.) If you post facto single out some particular sequence as ‘special’ (such as ‘6666666666’ or ‘life arising’) then of course that individual sequence is improbable, but that doesn’t mean that the dice were rigged (i.e., that there was an intelligent designer behind that sequence). It’s exactly as probable or improbable as anything else.

This is a much stronger objection. The basic challenge that it mounts is this: Why should we marvel at the occurrence of any one particular outcome when all outcomes are equally improbable?[8]

The objection suggests that we consider a die being rolled, so let’s do that. Imagine you’re in a casino and your opponent has gotten himself into a sticky situation. Let’s say he now needs to roll a die ten times and get ten 6s in order to win all your money, and if he fails, you will win all his. With you looking on, he rolls the die and–to your horror–he gets ten 6s in a row! As you watch your fortune draining away before your eyes, what are you thinking? Are you thinking, ‘How unlucky! Still, I guess that combination was as unlikely as any other’? Or are you instead thinking, ‘Hang on a minute–the odds of that happening were 60466176 to 1–I smell a rat’?

Dice can be deliberately weighted to make them very likely to come up with a particular number. How many 6s in a row would it take before the excuse ‘Well, that’s just as unlikely as any other result’ starts to lose its plausibility in favour of the competing hypothesis, ‘That die is probably weighted’?

If you play poker and your opponent’s hand comes up with four aces for three rounds in a row, do you shrug it off with the excuse that four aces is perfectly possible, and just as unlikely as any other specific combination of four cards? What about if it happens ten rounds in a row, or a million? At what point do you start to prefer the ‘cheating’ hypothesis to the ‘blind chance’ hypothesis?

There’s a simple principle at work here. Our objector pointed out, quite rightly, that an outcome that’s just unlikely doesn’t need any special explanation. But an outcome that’s both unlikely and significant, by contrast, is crying out for a special explanation. My favourite analogy is the millionaire lottery analogy: imagine a lottery where the entrants are one million millionaires and one pauper. The chances of any single individual winning are a million to one. If any one of the millionaires wins, no special explanation is needed; but if the pauper wins, the theory that the whole thing is a benevolent fix looks more likely, and the more often it happens, the more suspicious we should get. We should prefer the explanation that makes what we see more likely.

This, then, is the analogy with the universe. Our universe was set up in such a way that it is life-permitting. Any combination of key parameter values would be unlikely, but a life-permitting combination is both unlikely and significant. If there’s no Designer, the chances of the universe turning out that way are tiny. But if there is a (life-loving) Designer, the chances of the universe turning out that way are certain, or at least very much greater. So the fact that any outcome is equally improbable doesn’t affect the fine-tuning argument’s conclusion; we should prefer the theory that the universe was designed to the theory that it arose by chance.[9]


I have argued that the fine-tuning argument is strong, and cannot easily be dismissed. Ultimately, I don’t think it makes the existence of God any more likely, but this is not because of any weakness in the argument; it’s because the question raised by the conclusion (‘Why is the universe life-permitting?’) isn’t answered by positing a creator God. That suggestion just pushes the question another step further back: for why should a God exist with the right characteristics to create a universe? If the theist’s reply is that God can exist uniquely without the need for any further explanation, then the theist is admitting that unusual and significant things can exist unexplained, and if this is admitted, then we don’t need to postulate a Designer for the universe after all.

These concluding points obviously need further development, but this is not the place. For now, I am content to show that the fine-tuning argument can be consistently defended against many common objections without insisting on a theistic conclusion to that argument.


[1] In William Paley’s Natural Theology (1803).

[2] “Re: Probability of Star Formation” in the The Talk.Origins Archive linked from the Argument to Design index page in the Secular Web Library

[3] Martin Rees, Just Six Numbers (1999)

[4] John Leslie, Universes (1989), p.184

[5] In This Week, 13 September 1997, p.11. (See also Marcus Chown, “Cosmic coincidence,” New Scientist, 13 September 1997.)

[6] Rees, 1999, p.4.

[7] A similar point was made in a different context by John Leslie, The End Of The World (1996), pp.205 & 232.

[8] To enter the National Lottery in Britain, you select six numbers out of a possible 40. Each week, six numbers are picked at random by the lottery operators, and if all your numbers come up, you win the jackpot (or a share of the jackpot, if there’s more than one winner). If you enter the British Lottery, you would be well advised to select the following set of numbers: ’01 02 03 04 05 06.’ Why? Not because that set is more likely to come up than any other set. The odds are identical. But you should choose that set just because other people often don’t realise that choosing ’01 02 03 04 05 06′ would give them the same odds to win as choosing any other set. So hardly anyone will choose those numbers. Thus, if that set does come up, the chances are good that only you will have selected it–so you probably won’t have to share the jackpot with any other winners! (This reasoning, of course, is indirectly self-defeating. If more people come to understand it, they’ll start selecting ’01 02 03 04 05 06′ too, so you might have to share your winnings after all.)

[9] A more in-depth discussion of these issues is in my forthcoming article, “Is the universe significant?” in the journal Philosophical Writings.

[Editor’s note: See also “The Fine Tuning Argument–What’s the Big Deal?” by Matthew R. Opel]