If you spend any time reading the latest articles or books on neuroscience or consciousness, you should be very familiar with the claim that the soul is dead and the scientists’ fMRI scans have killed it. They present their evidence very dramatically and aggressively, and when they are done they just wait, daring you to come up with a response.
This would be humbling, sobering, faith-shaking indeed – and I’m sure it is for a lot of people – if only the soul they are knocking down were the same soul that Christians actually profess. Unlike a lot of misrepresentations of our faith and theology, this one is understandable. In common usage, everyone has an intuitive knowledge of what a soul is. “It’s the part of me that feels and thinks and loves,” someone might say. But if pressed to explain further what sort of thing it actually is, or where or how it exists, the common person would quickly stumble. And this is where the neuroscientists make their move. They show that they can explain our feelings, desires, and thoughts by means of brain processes. And then they conclude that they have shown that the soul does not exist or is at best a redundant concept.
However, I have noticed a theme in their explanations of the soul. They will usually start with a brief history of what has been said about the soul, and they seem to limit their discussion to two philosophers: Plato and Descartes. Both of these thinkers are well known for their dualistic philosophies, which means that they understood the soul and the body to be two completely different types of substances that just happen to be stuck together. Plato even saw the body as a prison that the soul spends its life trying to escape. So – the neuroscientists quickly set up this definition of what is commonly understood as soul, and then just as quickly pick it apart and show where it is weak and faulty.
But how many of us are Platonists or Cartesians today? Sure, in our day-to-day lives it may feel to us like our thoughts and feelings are ethereal wisps of immaterialiaty, but I don’t think most of us would deny that there is an intimate connection between our body and soul, as well as that our mental activities are grounded in our material brains. So what do we believe? The Catechism explains that “the unity of soul and body is so profound that one has to consider the soul to be the ‘form’ of the body: i.e., it is because of its spiritual soul that the body made of matter becomes a living, human body; spirit and matter, in man, are not two natures united, but rather their union forms a single nature” (365). This represents an understanding of the soul that is conveniently left out of the neuroscientists’ summaries. This understanding is known as hylomorphism, and it comes to us from Aristotle.
For Aristotle, all things are composed of matter and form. In their simplest terms, matter is the “stuff” and form is the shape, and together they make a “this thing”. But the form is not just the physical shape of a thing, it is that which makes something a “this type of thing” and not a “that type of thing”. And in living things, “soul” is the name given to the principle of organization – it is what organizes a thing’s matter into the type of thing that it is. A consequence of this is that not just any soul can be “stuck into” just any body; rather, “this soul” is the form of “this body” and conversely “this body” is the matter of “this soul”, creating the “profound union” mentioned in the Catechism. Through hylomorphism, then, we are able to understand humans (and plants and animals) as possessing an immaterial soul.
Here I would like to point out two things that Aristotle does not mean when he says the soul is immaterial. He does not mean it is immortal (we’ll get to that), and he does not mean that its only function is cognition. He ascribes to the soul five functions: nutritive, sensitive, appetitive, locomotive, and cognitive (De Anima, 414a30). To plants belong the first, to animals the first four, and to humans all five. This means that even our unconscious bodily processes such as digestion have the soul as their cause. So, “immaterial” does not necessarily mean “not having to do with the body”.
Since we are primarily concerned here with what sets humans apart from the rest of the animals, let’s look at the cognitive function by itself, or the mind. For Aristotle, we come to know the outside world through our senses and by abstracting the intelligible forms of things from their matter and thus forming concepts of them in our minds. But this process, from the initial sense perceptions to the recollection of them later through the imagination, is always dependent on the body. The part of the mind where these concepts are stored is called the passive intellect, which he says is destructible. “And there is, on the one hand, the sort of mind in which all things come to be, and, on the other hand, the sort by which all things are made, like some state, like light. For, in a way, light makes what is potentially color in act. And this mind is separable and impassible and unmixed, being in substance act” (De Anima, 430a15). And this latter is what has been called the active intellect, which he says is immortal and eternal, and “without this [the passive intellect] understands nothing” (430a25).
So, putting this in terms of modern science, my theory is that the passive intellect corresponds to the function of the brain with its storage and processing of information, and the active intellect corresponds to something like consciousness, by which we are able to give meaning to our perceptions and thoughts. Interestingly, Sam Harris – materialist philosopher and cognitive neuroscientist and author of the book Waking Up: A Guide to Spirituality Without Religion – has this to say about consciousness:
Whatever the ultimate relationship between consciousness and matter, almost everyone will agree that at some point in the development of complex organisms like ourselves, consciousness seems to emerge. This emergence does not depend on a change of materials, for you and I are built of the same atoms as a fern or a ham sandwich. Instead, the birth of consciousness must be the result of organization: Arranging atoms in certain ways appears to bring about an experience of being that very collection of atoms. This is undoubtedly one of the deepest mysteries given to us to contemplate. (Harris, 53)
At this point, a fair question at this point would be whether the Aristotelian soul we have been discussing can be reconciled with the “spiritual soul” that we hold by faith. Lucky for us, Thomas Aquinas already asked and answered this for us. As explained by Joseph Magee, “Aquinas’ answer is that the soul has its own act of existence which it communicates to the body, but that, without the body, it is not a complete substance (since it has an essential relation to the body). (Summa Contra Gentiles II, 68) Consequently, without a body it cannot exercise any of its natural activities. Thus, the rational soul can exist without the body, but it cannot do anything in, what is for it, an unnatural state. The separated soul, then, needs God either to reunite it with its body, or infuse it with knowledge, both of which would be supernatural gifts.” So, in short, yes. This also helps to explain why it makes sense that we would believe in the resurrection of the body; because as humans, we are not merely soul, or merely body, but a profound union of the two.
So – what I have attempted to do here is not to prove beyond a doubt that humans possess an immaterial and immortal soul. Rather, I am merely trying to defend such a belief against those who would hastily conclude from their science that it is irrational.
I think it is similar to the change that occurred in the minds of believers as a result of Darwin’s On The Origin of Species: By Means of Natural Selection. Before Darwin, people had a particular way they imagined the creation of the world to have happened, but after he published Origin of Species they had to reformulate their understanding in light of the new scientific evidence. But, contrary to the belief of some atheist scientists – and fundamentalist Christians – the theory of evolution does not disprove the existence of God or make his creative powers obsolete.
In a similar way, the discoveries of modern brain science do not render the soul obsolete. Rather, they enhance the knowledge we have by faith by imbuing it with fuller meaning and a richer texture as we discover more about God’s creation.