Today, I’m going to begin our discussion of God, which philosophers commonly define as an all-powerful, all-knowing, perfectly good being. (In philosophy-jargon, this is “omnipotent, omniscient, and omnibenevolent.”) In this lecture, I’m going to be talking about what philosophers call “/a priori/ arguments” for the existence of God. To say an argument is “/a priori/” is to say it can be made without appeal to any specific facts about how the world is, without any evidence in the historical, scientific, or legal sense. If you want to avoid the jargon, you could call them “office chair arguments”–arguments a philosophy professor could make without ever leaving his office to investigate the world.

How many people have heard someone say something like this: “Why is there something rather than nothing? It must be because God created the universe”? How many people think this is a good argument?

This argument is known as the cosmological argument, or maybe should be called the “crude cosmological argument,” as there are more sophisticated arguments with a vaguely similar main idea. I think the argument as I gave it, and as I’ve often heard people give it, is a pretty bad one. The problem is this: God is an enormous something. If you’re asking why there’s something rather than nothing, God, if he exists, will be part of what needs to be explained. If you ask where the universe came from, you must also ask where God came from.

There’s a take home lesson here that you can apply to a lot of things: when assessing a claim, it’s worth probing it with a few simple questions, to see if the advocates of the claim are being consistent in their principles.

Next point: a lot of arguments for the existence of God have this form. You could call this sort of argument, in general, “the argument from philosophical problems.” Where does consciousness come from? Where does morality come from? Where does logic come from? “It must be God!” say some people. And the problems are exactly the same as the problems with the crude cosmological argument: God himself would need an explanation, so it’s not clear invoking God helps. Also, as I hope you’ll see when we discuss some of these topics later in the course, once you really understand what’s so puzzling about these questions, it’s not clear how God could, even in principle, answer them.

For example, take morality. Maybe you think what’s puzzling about morality is this: if morality is human-based, then humans could decide that, say, rape is good, and then rape would really truly be moral. So we need God to give objectivity to morality. But it seems like there’s the same problem with basing morality on God: he could order some horrible act, and then it would really truly be moral. If the 9/11 hijackers were right, that Allah wanted them to crash those planes into those buildings and kill those thousands of people, that would make it moral. If this worry doesn’t seem real to you, because you don’t think God would do such a thing, the mere possibility of God doing so is what creates the problem. I’d also note that in the Old Testament, God does on various occasions order the Israelites to massacre other tribes, or to kill anyone who worships false gods.

For history buffs, the worry that basing morality on God makes morality arbitrary is a very old one, which goes back to Plato’s dialog /Euthyphro/. It’s often called the Euthyphro argument or Euthyphro dilemma. Something you can bring up at parties to impress your friends.

The problems I’ve described are mainly a problem for office-chair arguments, that ask some philosophical question and propose God as an answer. But it can also show up in arguments that are supposed to be based on evidence, like the argument from design. Proponents of the argument from design will point to specific details of biology, like the eye, or the molecular mechanisms cells operate on, and take it as indicative of divine design. Usually they seem to be saying that it’s specific facts that indicate design. But sometimes the debate ends up this way: the things in question are explained, and then the advocate of design demands an explanation for the explanation, and seems ready to demand a further explanation for any explanation you come up with. When that happens, it’s appropriate to ask how you explain God.

Final point on this argument: sometimes, when people talk about morality or consciousness as evidence for God, they suggest that atheism must be false, because naturalism can’t account for these things. This is a confusion between atheism and naturalism. Atheism is just the rejection of theism, the belief that God exists (“theism” comes from the Greek /theos/, which means “god”). Naturalism is usually understood to be something stronger, entailing, perhaps, strict materialism or strict physicalism, though philosophers aren’t consistent in how they define it. At any rate, rejecting God doesn’t obviously commit you to accepting some strict form of naturalism. For example, towards the middle of the course we’ll be discussing the idea that the mind is immaterial. One of the leading proponents of that view in academic philosophy today is David Chalmers, who will tell you flat out that he’s an atheist.

The argument from philosophical problems was one of the big office-chair arguments I wanted to discuss today. The other is the ontological argument. The ontological argument is one that a lot of philosophy professors feel compelled to teach. It’s considered one of the three main arguments for the existence of God, along with the cosmological argument and the design argument, both which I’ve said a little about and will say more about in coming classes. The reasons they’re considered the big three are almost entirely historical: the cosmological and ontological arguments were considered a really big deal in the 17th and 18th centuries, and discussion of the design argument really started to get going around the end of the 18th century. Also, the 18th century German philosopher Immanuel Kant claimed that they were the only three arguments for the existence of God.

Now, the 18th century was a long time ago, I’d like to think that philosophy has made advances since then. And Kant had some pretty funny ideas. There really isn’t a good reason to be beholden to them. And while there are still plenty of people who take the cosmological and design arguments seriously, it seems like hardly anybody these days thinks the ontological argument is good for anything other than causing headaches in undergrads [laughs maniacally]. Even Alvin Plantinga, it’s main defender today, doesn’t claim it proves the existence of God–he says its reasonable to accept the assumptions of the argument, so its reasonable to accept its conclusion.

In spite of all this, I’m going to cover the ontological argument, because the the argument, and related ideas, still pop up from time to time. One key idea in the form of the ontological argument I’ll discuss is that of a necessary being. That means a being that could not possibly have not existed. Here, “possibly” is used in a very broad sense–in the sense that it seems possible that the laws of physics could have been different. In this sense, it isn’t impossible to go faster than the speed of light, or create a perpetual motion machine. But proponents of a necessary God claim he couldn’t possibly have not existed. The idea of a necessary being is never used for anything other than God, but a related notion you should know is that of a necessary truth. The paradigm case is taken to be mathematics: not only does two plus two equal four, it couldn’t have equaled anything else.

One reason this idea is important is some claim that since God exists necessarily, he doesn’t need an explanation for his existence, so the cosmological argument turns out to work. The problem here is that the claim that God exists necessarily is an awful big assumption which, among other things, would entail that he exists. It seems like we need a proof of this, which would render the cosmological argument superfluous. The ontological argument purports to be such a proof. This is why Kant claimed that the cosmological argument depended on the ontological argument.

Here’s a statement of the ontological argument from Thomas V. Morris’ /Philosophy for Dummies/, the first book on philosophy I ever read:

1. God is the one and only greatest possible being. (By definition)
2. A greatest possible being has the greatest form of existence possible, which is necessary existence, or existence in all possible circumstances. (By definition)
3. It is at least possible that there is a God. (There is a God in some possible set of circumstances, whether they are actual circumstances, or fictional, yet possible ones)
4. A God who exists in any possible circumstances exists in all. (From premise 2)

Therefore,

5. God exists in the actual world. (In the circumstances in which we actually find ourselves)

Now let me give you the main points of Morris’ commentary on this argument:

The ace card here is the idea of necessary existence, or existence in all possible circumstances. God, according to this conception, is definitive of the realm of possibility. Any being that could exist in some circumstances and fail to exist in others is a less than absolutely perfect being. A perfect being must be so great and must have a form of existence so strong that it could not possibly fail to exist. God must necessarily exist…

The most controversial part of the argument, for philosophers who resist it, is Step 3… But it is our usual procedure in philosophy, as in life, to proceed on the basis of “innocent until proven guilty.” Here, the application of this presumption would be that we should treat the concept of God as consistent, coherent, or possible until we have some good reason to do otherwise.

And that’s about all Morris gave, back when I was in middle school reading philosophy for the first time.

Now I have some questions for you: how many think this is a good argument? Now for real honest: how many people even understand this argument? For those of you who don’t understand it, how many think it just might be a good argument anyway?

I’m going to do my best to explain this argument to you, and argue that it doesn’t work. But I also want to try to convince you that when you encounter something in philosophy you don’t understand, you shouldn’t assume it makes sense. And I want to show you how to figure out that something probably doesn’t make sense, even if you don’t really understand it.

Here’s the thing: open a biology or physics text book, and the assumption is that you can trust whatever its said. It’s been written and carefully reviewed by experts who know what they’re talking about. If you don’t understand something, your job is to re-read until you do.

Philosophy isn’t like this. As I said before, if philosophers knew what they were talking about, they wouldn’t be doing philosophy. So when you encounter something new in philosophy, you can’t always assume it must make sense, somehow.

How can we assess this argument, even if we don’t really understand it? We can do what we did with the other arguments I’ve mentioned today: ask questions, see if friends of the argument can really be consistent in their principles.

The ontological argument was first proposed by an 11th-century monk named St. Anselm of Canterbury. If you want to be even more confused than you are right now, go read his original statement of the argument, as it’s somewhat different than the one I’m discussing. Anyway, a fellow monk of his named Gaunilo had an issue with Anselm’s argument: it seems that the argument also proves the existence of a perfect island, which just seems silly. So there must be something wrong with Anselm’s argument.

A couple counter-points can be raised to Gaunilo’s island: one, you can say the idea of a perfect island doesn’t make sense, while that of a perfect being does. Also, if the idea of a perfect island does make sense, there’s nothing clearly impossible in the conclusion, it’s just kinda silly. So instead, let’s make the objection this: the argument also proves a perfect demon, a being just like God except evil. And this is clearly impossible, the point of being all-powerful is that you don’t have to share that power, especially with someone who will always want to do the opposite of you.

This is reason enough to reject the argument. But what’s going on with it? First point: you’ll be surprised to know that if you understand the terms correctly, the conclusion follows from the assumptions. There’s no fallacy per se, here. And Morris is right that the main controversy is over whether God is possible at all. Grant that, and the argument is hard to avoid.

Why’s this? The first key idea is that of a necessary being: God couldn’t possibly not exist. But we can’t just assume that, so let’s make the assumption that God is purportedly necessary being: if he exists at all, he exists necessarily. The second key idea is that of possible circumstances. If God is possible, he exists in some possible circumstances. Maybe a better term is “hypothetical situation.” The technical term–used by Alvin Plantinga, whose statement of the ontological argument Tom Morris based his off of–is “possible world.” A possible world is kind of like a hypothetical situation, except very narrow, “maximal”: for any detail of how the world might be, that detail is either included in or excluded from the possible world. Of course, it’s very hard to spell out every detail of a hypothetical situation, unless you’re saying “a world with nothing in it, except…” or “a world exactly like ours, except…” The idea is that even a single hydrogen atom out of place is a different possible world, which has led some philosophers, overly enamored of the idea of possible worlds, to suggest there might be a profound significance to the positioning of hydrogen atoms in distant galaxies.

Now suppose our purportedly necessary God exists in some possible world (possible circumstances, hypothetical situation, whatever), call it PW, but not the actual one, call it AO. But what if PW were actual and AO were merely possible? Then, because God exists, and is purportedly necessary, he would exist in all possible worlds! Including AO! But we tried to say that he doesn’t exist in AO, and the content of possible worlds isn’t supposed to change based on whether or not they’re actual, so we’ve got a contradiction. So if we define God as purportedly necessary, and admit he exists in some possible worlds, then he must in fact exist.

If this still isn’t clear to you, let’s return to the idea of mathematical truths. It seems like all mathematical truths are purportedly necessary–if they’re true at all, they’re true no matter what. So it doesn’t make sense to think that a mathematical claim is in fact false, but could be true in some other hypothetical situation. Now, there are many mathematical claims whose truth we may be unsure of. Off the top of my head, I have no idea how many prime factors 3719 has. And there are enduring mathematical puzzles that no mathematician in the world has solved: the Goldbach conjecture, which says every integer greater than two is the sum of exactly true primes. It works for every number we’ve checked, but we don’t have a proof for it. Could we answer these questions by means of an ontological argument? Of course not.

I think the moral of the story, is that you can never use the claim that some purportedly necessary thing is possible as the premise of an argument. It’s important to emphasize here that “possible” means really truly possible, not possible for all we know. For all we know, the Goldbach conjecture may be true, it may be false, but only one answer is really truly possible, only one answer can be by the nature of mathematics. Confusing these two senses of “possible” may be what makes the ontological argument seem like a good one to many people.

So I’ve covered the ontological argument, and what I called the argument from philosophical problems. Tomorrow will be dedicated to an in-depth discussion of the /Kalam/ cosmological argument, a more sophisticated form of the cosmological argument than the one I discussed today. Also, if you want a clear explanation of a lot of philosophical issues, don’t hesitate to check out /Philosophy for Dummies/, it’s a really great book.