Then there is the phrase "The God of the Gaps"™. In any long discussion on "Science and Religion", this phrase must eventually be deployed by one or the other party, either by the skeptic (with a triumphal tone as of one finally deploying his most powerful weapon) or else by the articulate and educated defender of a modern faith, showing his sophisticated ability to rise above primitive superstitions: "But that's the God of the Gaps™!" they say in response to a proposed act of the Deity, "We can't possibly believe in that!"
In the debate between Carroll and St. Craig, both participants had their obligatory five seconds of hate towards this idea. Craig:
This is not to make some sort of naïve claim that contemporary cosmology proves the existence of God. There is no God-of-the-gaps reasoning here. Rather I’m saying that contemporary cosmology provides significant evidence in support of premises in philosophical arguments for conclusions having theological significance.
It is certainly a true issue that we don’t know why the early universe had a low entropy and entropy has ever been increasing. That’s a good challenge for cosmology. To imagine the cosmologist cannot answer that question without somehow invoking God is a classic god-of-the-gaps move. I know that Dr. Craig says that is not what he’s doing but then he does it.
It is difficult to fight against a slogan delivered so frequently and with such conviction, especially when for some perverse reason educated and intelligent people on both sides insist on attacking the same strawman. But it is worth pointing out, that if the detractors of an idea could be defeat it simply by labeling it with a silly-sounding alliterative phrase, we wouldn't be able to believe in the “Big Bang” theory either.
As Carroll quotes the philosopher David Lewis as saying:
I do not know how to refute an incredulous stare.
These references to the God of the Gaps™ often function as a similar incredulous stare, not any kind of actual argument. (Mind you, the incredulous stares Lewis got were because of his belief in modal realism, i.e. every single logically possible world is equally real. Perhaps those incredulous stares just meant that ideas which flagrantly violate common sense should be assigned a tiny prior probability?)
Anyway, if the God of the Gaps™ is a fallacy, it's a very strange one. It is not any one of the standard textbook logical fallacies, and it is only ever brought up in theological contexts. On the surface, it sounds awfully like claiming that inference to the best explanation is a fallacy. Let me pull out some home truths here, and make the following bold statement:
Any time we ever believe in anything rationally, we do so because there is some kind of "gap" in our understanding of how the universe works, which is filled by postulating the existence of that thing.
In other words, all valid arguments that something exists are based on Of-the-Gaps type reasoning. This is just how reasoning (scientific or otherwise) works.
This is not to say, of course, that all gaps are best filled by postulating specific divine intervention. Of course not. Admittedly, Monotheists do believe the following:
All phenomena which occur in Nature do so because God sustains the world in being, thus (at least indirectly) causing everything.
But this hardly implies that all phenomena make equally good evidence for God's existence.
To the best of my knowledge, no Christian apologist has ever made the following argument: 1) Science cannot explain high temperature superconductivity [a puzzling phenomenon in condensed matter physics], 2) therefore an intelligent designer must have caused it, 3) therefore God exists. The reason is that it is obvious in this case that there should exist in principle an ordinary scientific explanation for this phenomenon. Superconductors involve complicated, messy physics and there is no particularly good reason to be surprised that we don't understand them fully yet.
(When an Intelligent Design theorist such as St. Behe argues that: 1) there exist phenomena in Nature such as bacterial flagellum which could not plausibly have evolved naturally because they have irreducible complexity, 2) therefore they must have been created by an intelligent designer, he is not committing any type of logical fallacy, let alone God of the Gaps™. The problem with his argument is that biologists have shown that his premise (1) is false, but it's a perfectly good type of argument, if its premises were really true.)
In other cases, such as the seeming low-entropy beginning of the Universe, or the fine-tuning of the constants of Nature to permit life, or why certain forms of life have conscious experiences, or why murder is wrong, or for that matter why there is a material Universe at all, it is at the very least not completely obvious that there will exist a natural explanation of the usual scientific type. There is a reason that theistic philosophers (not being totally stupid) latch onto these types of "big" or "fundamental" questions rather than questions about superconductivity.
It's actually the exact same reason why many atheistic philosophers will deny that these are meaningful questions to which one has a right to expect an answer. (Carroll does this in the debate, regarding the question of why the Universe came into existence. Assuming for the sake of argument that it did, he argues that this is not the sort of thing one needs an explanation for.) One could imagine a hypothetical physics which is in one sense a complete system of equations, and yet fails to answer some or all of these questions. In that case the Naturalist will (because of his conviction that Science is the only ultimate path to truth) deny that the questions are meaningful, while any person who feels unable to swallow this will have for themselves an argument for the existence of God.
Other, more optimistic Naturalists may hold to the belief that "Science will one day explain that". Since data about what Science will do in the future is sadly unobtainable, this type typically appeals to one of those historical just-so stories I mentioned in my previous post. To rephrase it once more (note that I do not accuse Carroll of making the following argument in all particulars; as I said I am using the debate as a springboard to talk about larger issues):
"Our superstitious ancestors thought that nearly all natural phenomena—the rising of the sun, the growth of the crops, etc. were attributable to numerous supernatural beings. Science has discredited nearly all of these ideas, but of course Science is not yet complete. The modern day defenders of religious traditions, therefore, although their original motivation for belief is gone, cling to these holes in our understanding as keeping a place for the divine activity. If only evolution or Big Bang cosmology or something leaves a place for God's activity, these religious types argue, then we have some role for Religion. But as Science continues to discover more and more, the gaps get smaller and smaller, and eventually these claims will disappear as well. To cling to this sort of Religion is worthless."
This type of reasoning (which is quite common, although I phrase it in my own words) tends to glide imperceptibly from popular pagan polytheists (who thought there was a divinity for every major or minor phenomenon) to the Hebrew monotheists (who resisted this trend as superstitious and wrong).
It was perfectly obvious to any pagan philosopher or early Christian that Nature proceeds according to orderly laws, and natural processes. Modern Science can take credit for unifying the description of many phenomena into common mathematical frameworks, but to act as though the existence of order in Nature is a modern discovery is simply absurd. It is true that this fact is in considerable tension with certain forms of Animism or Nature Polytheism. But certainly almost any astute monotheist living in the last two thousand years, is going to admit that God causes most things to happen, not through whim but through the operation of certain natural processes, which can be understood to some extent by human reason.
In this sense, Naturalism and Monotheism have a shared (and highly successful) common heritage. Both of them imply that the material world is not to be understood as divine, and that therefore it is fair game for impersonal study and observation. To act as though the fruits of this shared common presupposition is some type of falsification of one of these two positions is completely unfair.
So then, everyone should stop using this phrase, God of the Gaps™. In addition to being confusing and condescending, and not really a logical fallacy, it almost always indicates the presence of a strawman opponent. Very few religious people believe that God exists only to fill gaps in our understanding of Science. Let's argue against the real positions on the table.