How Do You Justify Inference?

            There’s an argument I heard the other day that I don’t think I’ve ever addressed on here: God is necessary in order to justify scientific inference. Let me see if I can summarize the idea for you.

            In scientific investigation, it is a baseline assumption that the universe will continue to behave in the future as it has behaved in the past. This is the assumption that allows us to make predictions based on data we have collected – i.e. this has to be true in order to make scientific inferences. After all, what good does it do to collect data about (for example) the strength of gravity and how it relates to mass if gravity might simply cease to exist tomorrow? How can you calculate satellite orbits, if there’s no reason to think gravity might not reverse itself five minutes after launch? It’s essential to believe that the universe will continue to behave the way it has in the past for any of that to make sense.

            But, the argument goes, how do you justify believing that? If you go for the obvious – that it’s an assumption that has always worked for us in the past – isn’t that circular? You can’t justify believing that what has worked in the past will continue to work in the future just because it always worked in the past.

            So, how do you get out of that circle?

            Here’s where God enters the argument. The claim being made is that the only possible justification for believing that scientific inference is valid, the only possible way out of the logical circle, is that God has revealed to us that the rules of this universe are constant. Therefore, doing any science at all (or, really, acting in any way as if the world is going to continue being just as coherent a second from now as it always has been in the past) is tacit admission that God exists.

            So… where do I begin?

            As far as I can tell, we don’t know that the laws of the universe won’t change; not in the sense of having absolute logical certainty of it, anyway. We act as if they won’t, because we have no choice.

            Or rather, you have the choice to act as if the universe is a sensible place where the future will continue to behave much like the past, or you can curl up into a catatonic ball and ignore everything going on around you until you starve to death. You can act in accordance with your observations of the world you live in, or you can die. That’s it. This isn’t a revelation from God, it’s a practical reality. Living things that act like none of their past experiences can inform their future actions die, and those that act like their past experiences are relevant to their future actions at least have a chance to survive.

            But it’s more than that. The alternative – that the rules of the universe are subject to change and we have no access to the reasons for this to happen – means we die and there’s nothing we can do about it. After all, as fans of the fine-tuning argument are fond of pointing out, if the rules of the universe were anything other than what they are, we couldn’t exist. If gravity changes, the earth’s orbit destabilizes and we all die. If inter-nuclear forces change, our body chemistry fails and we all die. If electromagnetism goes haywire, our neurons fail and we all die. These are not possibilities we can act on or prepare for in any way, and on the other side of such eventualities we simply cease to exist, so for purposes of determining our behavior they are utterly irrelevant.

            And even if there were to be a fundamental change that we somehow survived, we’d have no choice but to try and learn how the “new normal” works – a process that will require inference from our new observations.

            So, to summarize, we do not seem to be able to have absolute certainty that the laws of the universe will continue to be in the future what they have been in the past, but we also seem to have no choice but to behave as if they will. Whether it’s true or not, we are stuck with the assumption that it is.

            Now, that can be a very uncomfortable position to be in. The idea that the universe around you could possibly just cease functioning, and that you have no way to know that this won’t happen, can really suck if you dwell on it too much. Most of the time we just kind of casually accept the assumption that the universe will keep working and don’t dwell on it. And really, we’re kind of used to operating with a certain amount of uncertainty. After all, I can’t guarantee that I won’t get hit by a bus on the way to work on any given day, but I get up and hit the road anyway. We don’t need absolute certainty in order to function.

            So the argument falls apart there, since it’s built on the assumption that we need absolute certainty to act on inference. But we don’t need it, and we don’t have it. We just have reasons to want it, and those reasons are solely to assuage our own feelings of uncertainty.

            And that gets to the fundamental conceit of the argument. Essentially, it posits that human certainty is so fundamental to existence, the universe is so very much “about us,” that an “out” for this logical uncertainty must exist. Existence itself owes it to us. Humanity is so important that it simply cannot be true that we can have no choice but to accept something fundamental about the universe and yet not be absolutely certain about it. If the only thing one can think of that will give that certainty is a god, then that god must exist. The argument centers “making humans existentially comfortable” as the fundamental trait of the universe that determines what is real and what is not.

            What’s weird is that the person who was making the argument seemed to know it. When confronted with the fact that the argument “I believe God exists because I’m certain inference is valid, and I’m certain inference is valid because I believe God exists,” is circular, he acknowledged this was true. He just claimed that it’s a “good kind of circular,” because it allows him to have a consistent worldview. In other words, it makes him feel good, so he’s willing to accept it even though he knows it’s logically fallacious.

             OK, whatever. I suppose that if it works for him and he understands the limitations, fine. So why even bother to write about it? Well, because it’s not really an isolated case. It’s part of a frustrating class of arguments that has been cropping up a lot under the heading of presuppositionalism. They all pretty much take the form of “Idea X (scientific inference works, solipsism isn’t real, logical absolutes are valid, etc.) is so fundamental that I can’t imagine functioning without being certain of it. I can’t logically prove Idea X is true. But if I assume God renders Idea X true, I can pretend to be certain of it. Therefore, God exists, everyone who accepts Idea X must also accept that God exists, and anyone who says differently is lying.” It’s that last bit that takes the argument from bad to offensive.

            This is one of those apologetics that is all but guaranteed to frustrate and annoy atheists. Because it’s not actually an argument. It’s not actually trying to convince anyone, and, when pressed, even flatly acknowledges that it’s not convincing to anyone who doesn’t already believe. Its claim is that it doesn’t need to convince anyone, because everyone already believes it. It’s crafted for the sole purpose of creating a bubble of delusion for the believer by casting literally everyone else as liars. It’s utterly alienating; great for walling people off from each other. But as an actual argument for the existence of a god, it’s an abject failure.