This is the weekly Q & A blog post by our Research Professor in Philosophy, Dr. William Lane Craig.


Hello Dr Craig,

I find the "Fine Tuning Argument" for theism the closest thing currently to a compelling argument for the existence of God (at least that I have heard). However, it does suffer from a number of flaws that ultimately make it less than fully convincing.

The first is the multiverse hypothesis which you and many others have debated at length. In spite of the many criticisms levelled at it, this does remain at least a remotely possible alternative to an intelligent God as an explanation for the fine tuning of the universe for life and consciousness.

The second is much less commonly discussed, and it is that the fact (and I will take it to be a fact) that the universe is indeed finely tuned for life and consciousness is actually inimical to the very concept of God. So the Fine Tuning Argument for theism is ultimately self defeating.

Let me explain: Suppose we assume that theism is true, and that God exists and set about to finely tune the constants of nature to allow life and consciousness to exist. But let's suppose (for the sake of the argument) that He botches the job and accidentally tunes (say) the nuclear constant to be ten times its intended value. Well no problem - life and consciousness can still exist. Why? Because I am assuming that theism is true, and on theism life and consciousness can exist in any universe. In fact on theism life and consciousness don't even need a universe to exist. On theism life and consciousness exist necessarily.

I can cast this as a simple syllogism:

P1) If theism is true the universe is not finely tuned for life and consciousness;

P2) The universe is finely tuned for life and consciousness;

C ) Therefore theism is not true.

Clearly the Fine Tuning Argument requires the truth of P2, so the fault in this argument must be with P1. But look at the definitions involved in P1: Theism entails the view that life and consciousness exist necessarily; fine tuning entails the view that life and consciousness are not only contingent, but really, REALLY contingent - only possible under very constrained conditions. You could reply that the fine tuning only applies to the physical manifestations of life and consciousness. But my understanding is that under a broadly theistic worldview life and consciousness are independent of any physical manifestation. Obviously you will not be sympathetic to the foregoing argument, but I would be very interested to hear how you would respond to it. Thanking you in advance



Dr. William Lane Craig's Response

Dr. William Lane Craig

I don’t think that this objection is a good one, Damien. Leave aside your first misgiving. The fact that the multiverse hypothesis is “a remotely possible alternative” to design doesn’t disturb me in the least, since a successful argument (theistic or otherwise) needn’t establish its conclusion with absolute certainty.

Consider instead the second misgiving. It seems to me that

P1) If theism is true, the universe is not finely tuned for life and consciousness.

is plainly false. To say that the universe is finely tuned means that the fundamental constants and quantities of nature fall into an extraordinarily narrow range of values that enable embodied, conscious observers to exist. That fact seems to be well-established scientifically.

The fact of fine-tuning is not negated by the fact that God could have miraculously created observers in a universe governed by our laws of nature but not finely tuned. When it is said that values outside the narrow life-permitting range would have been incompatible with the existence of embodied, conscious agents, we mean that such observers would be naturally impossible. But of course God could have miraculously produced and sustained life.

What the objection really amounts to is a re-definition of “fine-tuning.” It is to assert that because God could create life in a universe with constants and quantities outside the life-permitting range, the universe is not really fine-tuned.  But in that case your P2) is false.  You can’t have it both ways.

Fine-tuning is about what lies within the productive capacity of nature. It says nothing about what is supernaturally possible.

The fact that God could have miraculously created life in a non-fined tuned universe hardly provides grounds for thinking that our universe is not fine-tuned. The constants and quantities do fall into the narrow life-permitting range, despite the fact that if they did not, then God could have miraculously created life anyway.  (Nor is this to say that “On theism life and consciousness exist necessarily.” There are lots of possible worlds where God doesn’t choose to create life.)

Note as well that the alternative that God miraculously creates life in a non-fine-tuned universe is hardly one that will appeal to the sceptic. If the only way to avoid a Cosmic Designer is to postulate miraculous divine action, then one is stuck with theism.

This Q&A and other resources are available on Dr. William Lane Craig's website.