Descartes thinks about the soul

 One of the strangest bits of thinking I know of is Descartes’s argument for the existence of a soul.

You can imagine not having a body. The very fact that you can imagine that means there’s a logical possibility that a body-less soul exists. (Unicorns don’t exist. But, since you can imagine them, there’s a logical possibility they exist. Perhaps they exist in a distant galaxy. We’d have to go there to confirm or reject the possibility.)

So far, so good. Here’s the strange turn in Descartes’s thought: He held that the fact that you could imagine one without the other — a soul without a body — meant that we have to be talking about two distinct things.

The argument rejects the position that the soul is just a convenient way of talking about characteristics of particular organisms or bodies. We say that John is an honest soul, and Sally is a scientifically-inclined soul, while her brother Sam is an artistic soul. We build the same convenient constructions with words like “minds” and “persons.” But when we’re talking about John’s honest soul, what some of us are really talking about is the organism known as John and some of his traits or characteristics.

That’s what many of us mean when we’re talking about a “soul” or a “mind.”

Descartes argues otherwise. The idea that we can derive “soul” from “body” is simply wrong. His argument contends that the logical distinction implies an ontological distinction — there must be two separate things. Two kinds of stuff.

I think the argument ingenious and fascinating. Philosophy teachers, when they are trying to show students the problem with Descartes’s argument, often tell the story of the Morning Star and the Evening Star.

For eons, human beings looked at the brightest object in the morning sky and called it the Morning Star. And they looked at the brightest object in the evening sky and called it the Evening Star. The two are logically distinct.

But, with advances in astronomy, we learned that both bright objects are not stars, but a single planet: Venus.

The Morning Star and Evening Star are logically distinct ideas, but they are same thing. Similarly, soul (or mind) and body might be logically distinct, but the same thing. Or so it seems to me.

But I have grown used to being wrong— or, rather, changing my mind — about such things. What hasn’t changed is the fascination with Descartes. I was a teenager when I first read this argument. It’s still one of the most interesting specimens in the literature of logic.

• Source: René Descartes, Meditations on First Philosophy. The argument is in the Sixth Meditation.