Yesterday, April 21, was the feast day of St. Anselm of Canterbury (1033/34—1109). As I did earlier this year with Thomas Aquinas, I want to take a moment to commemorate Anselm by sharing my relationship with him as a philosopher. Just about every semester, I teach introduction to philosophy, and in my course we spend some time thinking about one of Anselm’s most important contributions to philosophy: An extremely influential argument for the existence of God.
Anselm’s argument, which he set out in his book, Proslogion (1077-1078), is sometimes called an “ontological” argument, because it has to do with what is real. (Ontology is the branch of philosophy that deals with the ultimate nature of reality. Incidentally, ontological. method is my specialty in philosophy.) Here’s Anselm’s statement of the argument:
Even the fool is convinced that something exists in the understanding, at least, than which nothing greater can be conceived. For, when he hears of this, he understands it. And whatever is understood, exists in the understanding. And assuredly that, than which nothing greater can be conceived, cannot exist in the understanding alone. For, suppose it exists in the understanding alone: then it can be conceived to exist in reality; which is greater.
Proslogion, chapter 2
This is a pretty convoluted line of thought, so let’s step through it. The reference to “the fool” is actually an allusion to Psalm 14:1: “The fool hath said in his heart, There is no God.” (KJV) Even the claim that God doesn’t exist involves thinking something about God, right? So, the fool has some idea of God in mind. But what? Whatever else you might think of when you think about God, the one thing you have to think of is something like “the supreme being.” But your idea of supreme might be different from mine, so Anselm builds in a way to avoid tying the idea of supremacy to you or me: God, he says, is a being that is so great that no mind can conceive of any being greater than God. That’s what we mean by “supreme”: supreme to anybody and everybody. And that’s what Anselm means by defining God as “that than which nothing greater can be conceived.”
So far, this thing I’m thinking about is just an idea, right? So let’s ask this: Could this being that is so great that no greater being can be thought of – could that being exist only in my mind? Let’s say it does exist only in my mind as an idea: In that case, you or I or anyone else can think of something even greater, namely, a being that exists both in my mind as an idea and also as an entity outside my mind. In case you’re skeptical, let me ask you this: Would you rather have the $20 bill I’m thinking about only in my mind, or the $20 bill I’m thinking about that’s also in my wallet? If you’re like most people, you’d want the one in my wallet — because it’s “real.” So, anything that exists outside a mind that’s thinking about it must exist “in reality,” and not just as an idea in someone’s mind.
That’s how Anselm’s argument works: It starts with a definition of God as a being so great that no mind can think of a being greater than that, and it moves to the claim that, if that existed only as an idea, then actually it’s not a being so great that no mind can think of anything greater — because we can think of something even greater.
Now, you might be thinking, why can’t we apply this to anything? Suppose I’m thinking of the best Schnitzel, the Schnitzel that’s supreme among Schnitzel: Why can’t I claim that the “supreme Schnitzel” must exist not only in the mind but also in reality — or else it’s not really supreme. This was an objection mounted against Anselm’s argument by Gaunilon, a contemporary and fellow monk, in a clever piece of philosophy called “On behalf of the Fool.”
Anselm responded to Gaunilon’s objection by arguing that this argument only works on God, because God is not just supreme in a particular category of beings — like Schnitzel — but in every category of being. The supreme Schnitzel is supreme among Schnitzel, but surely we can think of beings even greater than Schnitzel. However, God isn’t just a supreme version of a god; rather, God is the supreme version of being. And if Anselm can make this argument stick, then it means that the concept of God is unique, because there’s only one being that is supreme as a being.
If this gives you a headache, you’re not alone: Ask my students! But the fact that some dude wrote this argument nearly 1000 years ago and we’re still reading and thinking and talking about it shows that this dude deserves to be remembered.