For the religious, soul is a very important notion. One of the problems many of a faithful disposition have with science is that it operates on a purely material view of the universe. That is, science posits that all phenomena, including human consciousness, can be explained through the interactions of matter. This leaves little room for an immaterial soul. But what exactly is soul, anyway?

In the common notion, the soul is described as the immaterial and immortal foundation of our personality, and our ticket to the afterlife. It is supernatural, meaning that its exact nature is beyond scientific or logical scrutiny, transcending all natural law. This makes determining exactly what a soul is very difficult, if we are to take these claims seriously. If a soul cannot be seen or tasted nor touched, has no size or position or any other physical property, what exactly is it anyway?

However, even if we are to accept the soul as inscrutable, there must be some sign of its presence in the observable world. An entity that cannot be seen, heard, felt, tasted, touched, nor be detected by sonar, radar or any other device, for all intents and purposes, does not exist. And even if we were to say that the soul operates by no physical laws, it interacts with the physical world, which is governed by such laws. Therefore, if there is a soul, it must associate with the body in ways that can be measured, tested, and defined by scientific theory.

Consequently, it is not enough to say that there must be a soul because we do not fully understand the workings of the brain and body. We have discovered that affecting the brain affects the faculties of cognition, emotion and agency that are associated with having a soul. See the case of Phineas Gage. Even if the mechanism isn't fully understood, it stands to reason the brain is responsible for those qualities. An immaterial soul can only be indicated by observing phenomena in the brain that can only be caused by interactions outside of space-time. So far, no such interactions have been found.

Now, you may say: "faith is the radar that finds the soul," but this cannot be as faith is not a perceptive faculty. It is an expressive faculty. When you express faith, you are making a statement of belief, and a belief is a consequence of perception and cognition. It is circular reasoning to say: "I believe in a soul, so there is a soul, so I believe in it."

Your heart may sink as you read this. "Is this man saying that there is no such thing as soul?" you may think, "Are you saying that we are robotic automatons, with no animating principle behind us? Are we zombies, wild and without welcome, our meager consciousness a simple illusion? What reason do we have to be good? Are we not real people?"

Wait a second—these objections have little to do with having an immortal soul. This has to do with the presence of real human qualities: the ability to feel and feel for others and to act as agents on our own behalf.

If the notion of lacking a soul is so intolerable not because it eliminates our bid for immortality, but because it deprives us of such basic humanity, then soul must be something much different from what we thought. If our ability to love comes from soul, and our ability to grieve and our ability to recognize ourselves in others, then soul is not a supernatural entity. It is a psychological property. It no longer matters whether the nature of the world is purely physical or not. We have the ability to love, hate, imagine, fight, dream, celebrate and triumph, regardless of what mechanism makes this possible. The spiritual is not the seeking of a far-off shore of inscrutable improbabilities, but the awareness of our psyche to its condition.

There need be no conflict between science and spirituality: they are paralel perspectives on the world. Science tells us how and why—and spirituality? Spirituality tells what it means to us.