The failure of fine-tuning arguments for god

When I ask people why they believe in god, their response almost invariably comes down to them being impressed with the complexity of the world and thinking that it could not have come about without some intelligent agent behind it. It is highly likely that this ‘reason’ is not the actual cause of their belief but a later rationalization for beliefs that they unthinkingly adopted as part of their childhood indoctrination into religion. When people become adults, they realize that saying they believe something because they were told it as children is likely to expose them to ridicule, and so they manufacture a superficially more rational answer.

The more sophisticated among them, who like to consider themselves as modernists who are accepting of science, argue that the properties of the laws of science and the inanimate matter that make up the universe seem to have just the right values to make life possible and that this implies that god must have chosen those values in order to enable the emergence of humans. This is what is known as the fine-tuning argument for god. (See also the discussion in the comments in yesterday’s post .)

In his article titled Does the Universe Need God?, cosmologist Sean Carroll elaborates on it.

In recent years, a different aspect of our universe has been seized upon by natural theologians as evidence for God’s handiwork – the purported fine-tuning of the physical and cosmological parameters that specify our particular universe among all possible ones. These parameters are to be found in the laws of physics – the mass of the electron, the value of the vacuum energy – as well as in the history of the universe – the amount of dark matter, the smoothness of the initial state. There’s no question that the universe around us would look very different if some of these parameters were changed. The controversial claims are two: that intelligent life can only exist for a very small range of parameters, in which our universe just happens to find itself; and that the best explanation for this happy circumstance is that God arranged it that way.

I have argued before that this makes no logical sense. It seems to imply that god was somehow locked into a blue-print for what humans should be like, and then had to carefully retro-engineer the evolution of the entire universe in order that the humans determined by that blueprint could emerge and survive. But this seems pointlessly Rube Goldbergish. The simpler thing for an omnipotent designer god to do would be to first create the universe and then design humans to fit into whatever emerged. After all, a god can presumably do anything and could have designed us to live in the vacuum of deep space or in the Sun or on any planet in the universe under any conceivable conditions.

But even if we take the fine-tuning argument of religious people on their own terms, we are by no means forced to the conclusion that a god is necessary. In fact, Carroll lists other possible alternatives:

  1. Life is extremely robust, and would be likely to arise even if the parameters were very different, whether or not we understand what form it would take.
  2. There is only one universe, with randomly-chosen parameters, and we just got lucky that they are among the rare values that allow for the existence of life.
  3. In different regions of the universe the parameters take on different values, and we are fooled by a selection effect: life will only arise in those regions compatible with the existence of life.
  4. The parameters are not chosen randomly, but designed that way by a deity.

So postulating a god is only one of many options to explain fine-tuning and by no means the most plausible one. It is not even the most attractive one.

Carroll then addresses the position that religion supplies the answers to the ‘why’ questions that science cannot.

These ideas all arise from a conviction that, in various contexts, it is insufficient to fully understand what happens; we must also provide an explanation for why it happens – what might be called a “meta-explanatory” account.

It can be difficult to respond to this kind of argument. Not because the arguments are especially persuasive, but because the ultimate answer to “We need to understand why the universe exists/continues to exist/exhibits regularities/came to be” is essentially “No we don’t.” That is unlikely to be considered a worthwhile comeback to anyone who was persuaded by the need for a meta-explanatory understanding in the first place.

Granted, it is always nice to be able to provide reasons why something is the case. Most scientists, however, suspect that the search for ultimate explanations eventually terminates in some final theory of the world, along with the phrase “and that’s just how it is.” It is certainly conceivable that the ultimate explanation is to be found in God; but a compelling argument to that effect would consist of a demonstration that God provides a better explanation (for whatever reason) than a purely materialist picture, not an a priori insistence that a purely materialist picture is unsatisfying.

There is no reason, within anything we currently understand about the ultimate structure of reality, to think of the existence and persistence and regularity of the universe as things that require external explanation. Indeed, for most scientists, adding on another layer of metaphysical structure in order to purportedly explain these nomological facts is an unnecessary complication.

It is hard for religious people to accept that there need not be an answer to every ‘why’ question. What is laughable is that after insisting that the why questions must have answers, religious people simply make up stuff, however preposterous or implausible it may be, without any evidence or even attempt at justification, and then proudly proclaim that they have solved the problem. It is better to accept that some things are just the way they are than make up an answer that has no evidence or reason behind it.

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