How Can I Know Souls Exist?

A poll was taken in class today as to whether we believed in something in us that is not simply our bodies (a soul, or something similar). A large number of people raised their hands to indicate that they didn't believe they had an immaterial soul. The question of how one can know if one has a soul or not was, I thought, a good one to write about.

The gospel is coming up against some rather unusual attacks in recent decades. One finds, more and more, that people do not believe themselves to be sinners, and that if they do, they don't admit it. It is a serious problem for the presentation of the gospel as a means of life if people don't believe they're dead. But another criticism of what was once presupposed to be self-evident is physicalism.

Physicalism simply means that the physical is all there is, and that all there is can be explained in terms of physical means. The consequence of this is elimination of souls (sometimes minds) and the supernatural in general. How can a Christian defend against this?

I think the first thing to do is to present the physicalist with some examples of things which are self-evidently true without physical instantiation, or things which must be true in all possible worlds. For example, the fundamental laws of logic are not only true in this world, but must be true in any possible world. They require no physical evidence for us to see their truth, and do not depend in any way on the physical world for their truth. Once you admit that something cannot exist and not exist at the same time and in the same sense, you will have established that there are things which exist independent of the physical universe (and if you take the case of mathematical propositions, an infinite number of things, at that).

So we are agreed that the soul is immaterial, and that immaterial things exist. But what exactly is a soul, and how do we know that that particular immaterial thing exists? I would define the soul as the (immaterial) seat of reason, intelligence, and personality. Some would argue that all of these can be explained physically, but Lewis shows in his argument from reason that rationality cannot be purely explained by physical causes without removing the basis for rationality itself. I do not have the space here to make a full account of his argument, but it can be found throughout his book Miracles.

I am not saying that there is no physical element in the explanation of these properties, only that it is not the full explanation. If we can even only establish that reason or our capability to comprehend truth cannot (and never can be) fully explained in terms of physical causes we have a large hole in our view of self, something which the Christian faith (and others) offer to fill.

Christianity gives us a theory regarding that gap in our selfhood, and at that point the question becomes probabilistic to a certain extent. If there are no other satisfying explanations, and Christianity (or any other religion) offers an account which provides one, we must weigh which of these accounts seems most likely, and we will be epistemically justified in believing that account.