“Scientists rightly resist invoking the supernatural in scientific explanations for fear of committing a god-of-the-gaps fallacy (the fallacy of using God as a stop-gap for ignorance). Yet without some restriction on the use of chance, scientists are in danger of committing a logically equivalent fallacy-one we may call the ‘chance-of-the-gaps fallacy.’ Chance, like God, can become a stop-gap for ignorance.”
You hear this weird turnabout argument a lot. “Oh yeah, well atheism‘s just another religion too!” “Do you ever apply your skepticism to skepticism itself?” It’s an elementary school playground retort — “I know you are but what am I?” — and it usually betrays a very deep misunderstanding of the point being responded to.
Let’s break this one down, shall we?
Theists are arguing that their deity’s existence is the best explanation for every natural phenomenon. But they’ve defined their deity to essentially be “the entity that does everything and is in control of everything that ever happens,” so it’s not surprising that they are able to offer it as an explanation for just about anything they like. What they haven’t done is offer compelling reasons to believe that such an entity exists in the first place. This is why we call it “god-of-the-gaps”: whatever gap in your knowledge there is, this concept of an omnipotent god rushes in to fill it, blocking out any potential for real scientific inquiry as well as any informative, useful explanation. If we think “God did it” is the explanation of that event, does that tell us anything about what might happen next? Does it allow us any sort of deeper understanding of how the universe functions? No, it doesn’t. It doesn’t even include any sort of predictions about how this “God” creature might tend to behave and what sorts of decisions it’s likely to make in the future. Basically, positing a “god-of-the-gaps” is just a fancy way of saying “I don’t know.”
Meanwhile, we know that probabilistic events really do happen in our world. See: genetic mutations, variation in inherited traits, radioactive decay … which dispersed seed pod happens to make it to fertile soil and which one dries up on hot pavement. We could make a ridiculously long list like this. Now, noteverything happens entirely due to chance, but no one actually claims that, and I don’t think that is Dembski’s objection; otherwise, he should equally object to gravity ever being used to explain an object’s motion because sometimes it’s actually electromagnetic forces. So, what limits should we place on “the use of chance” as a scientific explanation? How about: only say that chance plays a role in a phenomenon when we have a preponderance of evidence suggesting that it is in fact probabilistic. Never just say “chance did it” without doing any sort of investigations first. What’s that, you say? That’s the heart of the scientific method? Why yes … so it is.
Creationists tend to object to chance as an explanation for biological diversity because they can’t comprehend the large numbers and long timescales involved. (They’re not unique in having this handicap; just look at how many people play the lottery. Human brains aren’t well-equipped to deal intuitively with the very large or the very small.) They also tend to ignore the fact that the scientific explanation includes more than pure chance. We are not shaking up a bunch of springs and cogs in a box, then removing a fully-built airplane. We’re talking about random genetic mutations happening to different organisms all over the planet, plus natural selection pressures that caused organisms with the most beneficial mutations to go on to live longer and reproduce more. We have gobs of evidence that these processes of mutation and selection really do occur. Those processes have had something like 3.8 billion years in which to work… and chance can do a whole lot in that amount of time.
On the other hand, do we have any evidence pointing to divine intervention in our world? Do we have any indication of the mechanism by which that would take place? Do we even have a clear definition of which god is doing the intervening, or even what it means for something to be a god? No, we don’t. So don’t tell me that scientists are committing a “logically equivalent fallacy” to that of the creationists. That’s just wishful thinking on the creationists’ part. No, they have to shoulder the burden of their shame all alone. And scientists are going to continue admitting that they don’t know everything, keep collecting more evidence, and go on making claims only when they actually have evidence to back them up.