The god-of-the-gaps fallacy is a charge made by naturalists against theists.

First, some introduction. Naturalists believe that every effect in the universe has a material cause. Theists believe that it is possible that God, who is not material, can cause effects in nature. Theists think that these effects are detectable because the creating/designing capabilities of material causes are insufficient to explain certain effects either deductively (creating out of nothing) or probabilistically because of the limits of time and space available for material processes to act within (biological information). The naturalist thinks that all effects in nature have physical causes, the theist things that some effects in nature are caused by non-material causes.

In the past, some effects in nature were thought to be caused by God but later were found to be the result of natural (material) processes, often through the scientific method. Because the trend has been to explain these “gaps” in our knowledge with material causes, the naturalist now assumes that every effect in nature will be found to have natural causes. Even discontinuities in nature that are real, like the Big Bang, the fine-tuning, the origin of biological information, etc. are now assumed to have material causes, even though the progress of science has made these effects MORE DIFFICULT to explain with natural causes. The naturalist calls any attempt to attribute an effect in nature to a Creator/Designer a “god-of-the-gaps” fallacy, because the naturalist points to the past and asserts that a natural material cause will eventually be found for whatever gaps we have in nature.

But suppose a material explanation of every effect in nature could be found. Does that mean that there is no role for God anywhere?

Glenn Peoples writes:

Let’s imagine that the following is true: God does not intervene in the world. Once upon a time people who were more ignorant than we are thought that gods, angels, demons, spooks or spiritual forces lurked behind everything that we didn’t have a handy natural explanation for. But in fact, this is all god of the gaps reasoning, and God doesn’t intervene in nature at all. Never. There is a true natural account for everything that goes on in the universe that we know of.

If you don’t think that’s true, relax. We’re imagining, OK? I don’t think that the above is true, since I’m one of those crazy people who thinks that at least some miracles have taken place. But let’s suppose that the above account were true. Here’s where things take a step off the cliff of logic. Take the above account, and then add the following statement: “Therefore, since God isn’t required to explain any phenomenon, we have no need of the God hypothesis at all, and we have as good as shown that he need not be thought to exist.” God, some have said, can now be treated as a redundant hypothesis that explains nothing at all. Nothing.

And then Glenn cites John Lennox:

Science has been spectacularly successful in probing the nature of the physical universe and elucidating the mechanisms by which the universe works. Scientific research has also led to the eradication of many horrific diseases, and raised hopes of eliminating many more. And scientific investigation has had another effect in a completely different direction: it has served to relieve a lot of people from superstitious fears. For instance, people need no longer think that an eclipse of the moon is caused by some frightful daemon, which they have to placate. For all of these and myriad other things we should be very grateful.

But in some quarters the very success of science has also led to the idea that, because we can understand the mechanisms of the universe without bringing in God, we can safely conclude that there was no God who designed and created the universe in the first place. However, such reasoning involves a common logical fallacy, which we can illustrate as follows.

Take a Ford motor car. It is conceivable that someone from a remote part of the world, who was seeing one for the first time and who knew nothing about modern engineering, might imagine that there is a god (Mr Ford) inside the engine, making it go. He might further imagine that when the engine ran sweetly it was because Mr Ford inside the engine liked him, and when it refused to go it was because Mr Ford did not like him. Of course, if he were subsequently to study engineering and take the engine to pieces, he would discover that there is no Mr Ford inside it. Neither would it take much intelligence for him to see that he did not need to introduce Mister Ford as an explanation for its working. His grasp of the impersonal principles of internal combustion would be altogether enough to explain how the engine works. So far, so good. But if he then decided that his understanding of the principles of how the engine works made it impossible to believe in the existence of Mr Ford who designed the engine in the first place, this would be patently false – in philosophical terminology he would be committing a category mistake. Had there never been a Mr Ford to design the mechanisms, none would exist for him to understand.

It is likewise a category mistake to suppose that our understanding of the impersonal principles according to which the universe works makes it either unnecessary or impossible to believe in the existence of a personal creator who designed, made, and upholds the universe. In other words, we should not confuse the mechanisms by which the universe works either with its cause or its upholder.

John C. Lennox, God’s Undertaker: Has Science Buried God? (Oxford: Lion, 2007), 43-44.

I’m with Glenn – I think that God is a real agent who exists in time subsequent to Creation just like you and I. He can cause effects in nature like you and I, the same way that you and I can – by using our immaterial minds to affect the natural world freely. But even if everything has a mechanistic explanation – which I don’t for a minute agree with – that still would not rule out an intelligence acting to bring the entire universe into being fine-tuned for complex life, with certain potentialities that would unfold over time.