The Probability of God

One common argument for God’s non-existence used by outspoken theists such as Richard Dawkins is the improbability argument. The argument, as articulated in Dawkins’ book, “The God Delusion”, goes as follows:[1]

  1. The physical universe is a highly complex and improbable system.
  2. If a supposed God created the universe, he must be even more complex than the universe he created.
  3. Therefore, God is even less probable than the universe.
  4. So, God probably doesn’t exist.

Dawkins produces the argument with a “Aha, gotcha!” kind of flourish, but the underlying reasoning is logically flawed. Let me explain, but in order to do so, we need to understand the link between statistical probability and thermodynamics.

In the science of thermodynamics, the statistical probability that an ordered system (such as a universe) will arise spontaneously is inversely proportional to its complexity. The higher the complexity, the lower the probability. This is because ordered systems with high complexity also necessarily have high entropy. Entropy is a measure of potential disorder in a system arising from the number of possible states or configurations that a system can manifest which don’t work.

An example might help. If you found two bricks in the middle of a quiet road, with one brick perfectly and squarely on top of the other, it is improbable but still possible that they fell of the back of a truck and landed like that. There are only two bricks, so it is not a particularly complex system and entropy is reasonably low. But suppose that instead of finding just two bricks, you discovered a perfectly formed brick wall in the middle of the road, constructed to waist height and consisting of hundreds of bricks all perfectly positioned. This hugely more complex system has much higher potential entropy because there are trillions of different configurations in which the bricks could have naturally arranged themselves. Thus, in this scenario, the probability that the bricks fell off the back of a truck and arranged themselves into a perfect wall is so infinitesimally small as to be considered impossible in the real world. It would never happen.

But our universe is a much more complex system than a brick wall. Scientists of all philosophical persuasions agree that the physical universe comprises an extremely complex (and therefore, improbable) arrangement of matter and energy. The study of physics has shown us that the laws and fundamental constants of nature are precisely and complexly fine-tuned to an extraordinarily precise level that, coincidentally, is exactly the fine tuning necessary for life. As Dr Paul Davies (Professor Emeritus of Theoretical Physics, Adelaide University) wrote: “The physical universe is put together with an ingenuity that is so astonishing, with physical constants that are so impossibly perfect, that I can no longer accept it as the product of brute chance.”

To summarise: The higher the complexity of a system, the greater is its entropy and the less probable is its formation by random processes or chance.

This is, in fact, Dawkins’ first point in his argument for the improbability of God:

  1. The physical universe is a highly complex and improbable system.

So far, his argument is sound. His next point is also sound:

  1. If a supposed God created the universe, he must be even more complex than the universe he created.

So far, so good. The Creator must necessarily be greater than the creation, otherwise he would not have been capable of making it.

But then Dawkins’ argument falls apart because he makes an illogical jump. He argues that because God is more complex and thus more improbable than our physical universe, he therefore probably doesn’t exist:

  1. Therefore, God is even less probable than the universe.
  2. So, God probably doesn’t exist.

Can you spot the flaw? There are actually two. The first involves what is known as special pleading. Dawkins admits that the universe exists despite its high complexity and high improbability, yet argues that God doesn’t exist because of his … umm … high complexity and high improbability. You can’t have it both ways, Mr Dawkins! If one highly complex and highly improbable system or entity exists, it actually argues in favour of a second such entity also existing. Dawkins is making a special case for the existence of the universe, but not allowing the same case for the existence of God. This is special pleading, and it is disappointing to see such a crude sleight of hand being used by someone who should know better.

The second flaw lies in the complete lack of explanation for the universe’s highly improbable existence. Dawkins does not and cannot explain how such a highly complex and improbable system came into being by chance processes. The extraordinary fine tuning of the universal constants needs explaining, and random chance simply won’t do it. As Dr Robin Collins (Professor Emeritus of Theoretical Physics, North Western University) wrote:

“The chance of just two of these cosmological constants developing to their precise values by sheer chance, is one in 100 million trillion trillion trillion trillion trillion trillion. That’s more than the number of atoms in the universe! And that’s just TWO of the constants!”

The astronomical improbability of our highly complex universe is actually an argument for God’s existence, not against it. Dawkins has failed to see this.

Go back and look at that brick wall in the middle of the road. Look closely at it. Perfectly straight. Perfectly square. Each brick precisely aligned with the others around it. No sensible person would look at that wall and say, “This wall was formed by bricks falling randomly off the back of a truck”. In the real world, perfectly formed brick walls don’t randomly form themselves. They require a creator.

So does our universe. The complexity of the universe screams out for an intelligent designer. If the universe which is highly complex and highly improbable exists despite its astronomical improbability, the most logical explanation is that Someone of even greater complexity created it.

Statistically speaking, the existence of God is highly probable.


[1] Richard Dawkins, The God Delusion, Transworld Publishers, London, 2006, pp. 138, 171, 176