St. Thomas Aquinas' Theories of the Soul- Still Valid?

Are St. Thomas’ theories of the soul and its relationship to the person and the body still valid in the light of modern neuroscience?

St. Thomas was a great philosopher and you’d be hard pressed to find a contradiction in anything he wrote. Is it possible though that because he was working from a pre-scientific understanding of how the body works, he might have attributed natural processes to the ‘soul’. For example, intellect and will. Are these really properties of the soul, or are they merely the aggregation of hormones and other compounds like dopamine (will) in the brain?


Which ‘theories’ are you talking about, in particular? Just the attribution of intellect and will to the soul? Pretty sure that Thomas gets this from Aristotle, and that the idea itself springs from the long development of philosophy.

I don’t see how modern science of the body could call into question any philosophical or theological knowledge of the soul. Modern science uses data gathered by the senses to formulate hypotheses about how things work. When you are dealing with something that is not known directly to our senses, like the soul, modern science clearly isn’t the best learning tool.

I’ve been out of college for a while, but I’ll try to give my understanding of the Aristotelian/Thomistic soul/body relation. I was never a great student so I’m probably not hitting the nail on the head, but it’s a start.

The soul is the invisible animating principle of the body. It is prior to the physical, it is what makes our matter ‘run’. This is why the intellect and will are attributed to it, as they command our body to do things. By use of our intellect and will, we do things with our body that cannot be categorized as simple physical reactions. Seeing this, it makes sense to say that they have to reside in something outside of the body. The animating principle of a thing cannot be the thing itself.

Some confusion occurs because we see that our body does affect our intellect and will, which we say reside in the soul. Brain damage, for instance, removes from us capacities that we ascribe to the soul. All this really shows, however, is that, as ‘integrated’ beings, our body is necessary for our soul to receive and express things. So when the body is damaged, the soul is cut-off, so to speak.

As far as hormones and all that, just because there is a bodily reaction that accompanies a movement of the soul does not mean that the soul does not exist and does not move in a prior way. My love for a girl will have a (higher) component that resides in the soul, as well as a more purely bodily-attraction component, and a whole bunch of middle-ground where my heart goes pitter-pat because my soul and body are telling me that she is the bees-knees. So there is definitely some gray area, especially since our soul and body are connected; a movement in one usually creates a movement in the other. But one is prior.

So as far as I can tell, modern neuroscience shouldn’t cast any doubts on what St. Thomas says. It just gathers data about what’s going on with the body when our soul is moving a certain way. Hope this helps!

It is still valid.

Thanks for your reply. It seems to me as far as most of it goes, it might be like the classic example of a window allowing light to come in but not the source of light itself. In other words, the brain is a transducer or like a television set. Break a transistor or an IC chip and the lights go out. If you didn’t really know all there is to know about the TV, you might assume that the TV actually produces the picture on the screen.

I guess the question is, do we know enough about the brain to decide whether or not we are dealing with a reciever or a producer? We know enough about glass and televisions to deduce that they are recievers, but what about the brain?

Also, I do not understand the idea of a soul as the animating principle. Wouldn’t that be the nervous system? Or cells? I’m not saying I disagree I just do not understand.

What you need to understand is, metaphysics deals with things on a much more fundamental level even than quantum physics; mere neuroscience (which operates on the quaint idea that particles are wholly real) is barely skimming the surface.

First off, discard this vague concept of “soul”.

What we’re dealing with is formal part: that which makes it what it is. It is also what grants a thing all its traits (which are ontologically known as perfections), since they inhere in the thing by nature. Thus reason and forty-six chromosomes inhere in humans, claws and eighteen toes inhere in cats, etc.: by nature.

So of course, since life is a trait of humans, the formal part is its principle. Once the traits of the human change enough, say by pieces being broken off, it ceases to be a human, and its formal part departs. It dies. Some of its traits are more important than others–they are necessary conditions to it existence as a human being.

Now the human’s formal part is called subsistent: it can exist with none of the human’s traits. In other words, humans have immortal souls. But the formal part is not the human; it is simply the essence of the human. A thing and its essence are only the same when it is pure essence, what nonphilosophers call pure spirit.

On the contrary, modern science has actually been validating the position of St. Thomas Aquinas over and against that of recent materialists.

Just one example of this is the fact that if ideas were produced by the brain, you would expect the same, or at least very similar, brain patterns and chemical structures for the same idea. What we’ve discovered, however, is that two people’s brains work with the same “idea” and process very differently, even going so far as there being a fundamental difference in how men and women process the same ideas and information with different parts of the brain!

In short, there is no physical/chemical correspondence between the “idea” of a circle in your brain than there is in mine; the only thing they have in common is the “pure form” of circle.

This isn’t to say that brain damage doesn’t affect how we process information, but then even St. Thomas Aquinas understood that the state of the brain affects the non-material states of the brain. From the Summa Theologica I-84-7:

First of all because the intellect, being a power that does not make use of a corporeal organ, would in no way be hindered in its act through the lesion of a corporeal organ, if for its act there were not required the act of some power that does make use of a corporeal organ. Now sense, imagination and the other powers belonging to the sensitive part, make use of a corporeal organ. Wherefore it is clear that for the intellect to understand actually, not only when it acquires fresh knowledge, but also when it applies knowledge already acquired, there is need for the act of the imagination and of the other powers. For when the act of the imagination is hindered by a lesion of the corporeal organ (my note: the brain), for instance in a case of frenzy; or when the act of the memory is hindered, as in the case of lethargy, we see that a man is hindered from actually understanding things of which he had a previous knowledge.

Here he is pointing out that even though the intellect’s operation is purely non-physical in itself (the understanding of pure ideas), the intellect makes use of the imaginative power of the soul in order to work with the “pure idea”. So our pure knowledge of “circle” doesn’t depend on the brain, but whenever we use that idea we also imagine it, which is the operation of the senses, and this occurs in the brain (by imagination) rather than the organs we received the initial impressions of “circle” from (for example the eyes in the case of its shape). Aquinas is saying that we may still have the pure idea of “circle” stored in our immaterial intellect, but we can’t process it properly without the unhindered working of the brain since the way we understand “circle” is by senses (or imagination, in the case of already-stored ideas).

Aquinas’ arguments for why the intellect and will must be non-material also still hold up, and great modern materialist thinkers have actually bumped into them directly in their own studies without having even read St. Thomas or other medieval philosophy. The most prominent of these is the materialist Dr. John Searle, who studies the theory of the mind, and who has poured a LOT of cold water over the notion of truly intelligent computers in recent years. The funny thing is that Searle DOES believe that the mind is purely material, but has discovered that the way it behaves is utterly unlike what we would expect from a purely material system. He simply believes that this is due to some materialistic causes that we don’t yet understand, and which couldn’t ever be replicated artificially, but what he’s discovered fits up exactly with what Aquinas used when arguing for the immateriality of the intellect.

For an interesting read on this subject I recommend the thesis written by Br. Christopher Fadok O.P., a former student of Dr. John Searle.

I’ve found that Aquinas’ arguments are a LOT more robust than I would have ever guessed. It’s a shame he’s not studied more outside of the Church, because he could really shed some much needed light on some of our modern gaps of understanding (as in the case of Searle, who admits he’s never read Aquinas!)

Peace and God bless!

Hey thanks for these posts, they have helped me a lot. You see, I didn’t really know what the “soul” meant, I thought it basically meant that ancient people did not know what the brain did, and they thought that something outside had to make it go. Pretty simplistic, but that’s why I asked.

One more question though- how does the idea of the soul being the animating principle of the body work out with science, because I guess biologists would put this down to matter working with matter shaped through natural selection with modification (i.e., evolution)?

It seems to me that any expression of “natural reason” that relies on Aristotelian natural science concepts that have since been disproven needs to be revised. The explantory role of the soul is shrinking, because more and more things can be explained by natural science alone. Take something like the movement of the stars; this once required an explicitly divine account of motion; we now know it’s the effect of gravity. The same can be said for much that was previously described as mind or soul, i.e., impulsive actions, emotion, mood, etc.

We can believe in God and recognize the beauty of these natural principles–gravity, neuroactivity, emotion–but we should always remember that truth cannot contradict truth, and if a truth is revealed by natural science the merely deductive reasonings of Aristotle or his student Aquinas must be revised accordingly.

Since at least some of what Thomas said was based on now discredited Aristotelian natural science, it should be revised.

Gravity, that I’ll bet you think is one of the four forces (it’s not).

Unfortunately all of those things we once thought were mind, are mind; a child could tell you the philosophy of mind is just where we left it a hundred fifty years ago. It’s also obvious you have no conception whatsoever what is meant by “soul.” This despite my having defined it in my post.

Some of Aristotle’s physics have been superceded, but the METAPHYSICAL principles remain sound; did you notice how often I said METAPHYSICAL in my post?

Besides, many of what you think are physical statements are actually metaphysical; you just don’t know the terminology.

Aristotelianism is the only sound metaphysic humans have ever come up with; it forms the basis of quantum theory (read some Schroedinger). Everyone else is either a Platonist or a Lucretian Atomist–or an Acosmic Monist.

Out of curiosity, would you offer an opinion about astronomy if you weren’t sure of the difference between a galaxy and a solar system? So why do you offer opinions about philosophy when you obviously know nothing whatsoever about it? You don’t even get Aristotelian physics right (that description of his celestial motion is a dimestore caricature), what makes you think you have a right to an opinion about his, or Aquinas’, metaphysics?

“Explanatory power of the soul”…that’s just rich. As though the four causes were some mere scientific theory.

I’m gonna heat up a bag of popcorn. Keep it coming. :thumbsup:

Hastrman, I don’t think that tone is appropriate or productive here.

But I do know a bit about Aristotle. I studied him at the University of Chicago, along with St. Thomas Aquinas. I was a philosophy major and graduated with special honors. I studed with Leon Kass, Joseph Cropsey, and Alan Bloom, among others. I also have read Aristotle extensively on my own. I am finally quite familiar with Alisdair MacIntyre’s discussion of Aristotle and the extent to which his metaphysics depends upon his physics, i.e., his erroneous views of natural science, in his excellent works After Virtue and “Whose Justice? Which Rationality?”

You can theorize mind all you want, but that’s the great defect of classical philosophy, it was largely devoid of experimentation and the scientific method. That’s why so little of what it said about the natural world was particularly useful or capable of being transformed into technology. Descartes and Hobbes and the moderns have a metaphysics too, and it’s probably worth paying some attention to not least because it’s delivered on its promises of order of magnitude increases in our ability to manipulate the natural world.

The mind is not a product of pure reason, an abstraction like the classical notions of atoms. It is a thing that has a clear relationship to various phenomena we see and experience, namely, emotion, activity, decisions, freedom, etc. We now know that at least some of these things, even things we experience subjectively as choice and will and so forth, have a strong, materialist explanation in the structure and chemistry of the brain. Why else, if the mind is so divorced from the brain, can a few pills radically alter behavior, both for good (dealing with depression) and for naught (yielding pathological gambling in the case of some Parkinson’s drugs).

Now what does this mean for Catholic theology of the soul? I don’t know, but it must be modified, or it risks becoming moribund, bound into syllogistic formulae that are increasingly anachronistic and, in some cases, demonstrably false.

How cute, he thinks he can trump the single greatest achievement of human thought with name dropping and his little tribal totem, empiricism. He thinks the ancients, who drank more wine in a day than he looks at in a week, did not know the mind could be impeded by drugs. He seems to be mixing up Aristotelianism with a very bad caricature of Platonism, or even of some pre-Socratic or other. That idea of the ghost in the machine is the furthest thing from Aristotle that there is.

You also argue from authority. “I studied under X and Y and Z, I am familiar with W’s analyisis of blah blah blah”. They’re all very prominent and prestigious I’m sure–but their ideas are bad and that is the end of them, else why would their student say ignorant things that I, who have studied under nobody and get my texts from mass market paperbacks, can refute without breaking a sweat?

You obviously slept through the part where it was explained, Aristotelianism *denies *that the mind is divorced from the brain (it also denied classical atomism, nice to see you got your money’s worth). Do you even know what is meant by “formal part?” Of course the mind is not “a product of pure reason”; what reasons, except the mind? You say idiotic things like that and you wonder why I condescend to you? As well say “The liver is not a product of pure bile”.

The dirty little secret of philosophy departments, I dread to inform you, is that they are actually “history of philosophy” departments. And your history of philosophy apparently stopped short of noting that Schroedinger and Goedel between them blew Descartes’ comfortable little empiricist mud-hole to so much confetti. Or did you actually think particles were real? Unfortunately quantum theory is best explained…by Thomistic metaphysics, with some modifications (Maritain and Adler and others did those modifications in the fifties). Ditto, the laws of physics are consistent…which means some of them can only be proved by reference to something else, therefore there is something that is not part of those laws. And then there is the interesting point that whatever it is about an observer that allows it to observe (if you don’t know the significance of observers in quantum physics, I’m not going to explain), must not be describable by the laws of physics…because if it was it would be only another set of probabilities and you’d be trapped in infinite regress.

Tell me, what is it about an observer, qua observer, that allows him to observe?

Gee, Davy, do you think it might be “the mind?”

Did you have fun at keggers while you were at school? I’d hate for the experience to have been a total waste.


Charity please… if this devolves into name calling, then we’ll never figure anything out.

I’m done. But I brought up what I brought up about my education because you insulted me, if you recall.

Your personality and manners could use some work; one wonders how many people you’ve alienated with your condescension even though you’re obviously bright and could do a lot to help explain these things to Catholics and non-believers alike. You’ve read a lot of Aristotle, but must have skipped his Rhetoric.

I’ll pray for you . . . to St. Jude.

Cartesian empiricism…Hijikata Toshizou on a bicycle, is it 1854?

In philosophy, at least in philosophy that has the right to the name of Socrates’ movement (as opposed to Sophists like Descartes), we don’t use the word “soul”. We refer instead to the formal cause, that which makes a thing what it is. Aquinas calls it “quidditas,” that is, “it-ness”. It is the same as the essence of a thing.
A soul is the animating principle of a living thing, because it is also the reifying principle of it. That is, not only does it make it alive, it makes it a thing. It is simply whatever it is about the thing that makes it whatever it is.

Oh, I can’t resist. But I’m only going to ask questions, which intelligent people un-read in Aristotle may be thinking.

Who is to say anything has an essence or formal cause? How do you prove this? Isn’t this just a taxonomical title for a random observation about something? Who is to say “this quality” is the essence and “this quality” is superfluous. Take human beings. We have some unique traits: reason, emotion, honor, walking upright, a certain kind of DNA, etc. What’s the essence? And if the essence is reason, then how are comatose or retarded human beings “essentially” human? (Surely they were not seen as such to the pagan Aristotle.)

The arbitrariness of this telelological account of nature seems more and more manifest. We know that horses, for example, are not made of “horse molecules” or “horsey stuff” but instead are made up of the same things (molecules and such) as any other animal, which in turn is the same stuff that plants and non-living objects are made of. It is simply arranged in different patterns.

Who is to say that any of these apparently different things with apparently different qualities has an “essence” different form any other? Science relies on falsifiable hypothesis and asymptoptic approaches to a unified explanation with predictive power. It doesn’t puport to answer final questions. Metaphysics does. But what proves if a metaphysical theory is correct or wrong or somewhere in between? How do you test it?

Things may appear teleological and actually be random. How do we know that there is a real telos among anything in nature and it’s not just some random quality we’re focusing our attention on? How can we know we’re right and not merely speculating as the ancients speculated about fire-earth-wind-and-water, atoms, Platonic forms, and all the rest.

Please keep the discussion civil, people. I’d hate to have to close the thread but I will, if I have to.

Modern neuroscience is a bed of straw and DeCart was an idiot. I am not just because I think. I am, because God Thought and still Thinks.

Modern neuroscience is brilliant and very important; modern science is the best way we have to know the Cave. But that’s all it’s good for; you need metaphysics to know, for instance, that there is any matter to do science about, and that it’s knowable.

Incidentally, mansizedtarget, how do you know your empirical tests really test? You don’t, of course; because first you have to have metaphysical ideas about causation. And your denial of essences is merely the error of the Theravada sect, oversimplifying Anatmaism and thinking one can deny natures/essences/forms while still believing in matter. As the Vajrayana sect proved, it is illogical to say that forms don’t exist but matter does–in order to exist matter must have a form. Your alternatives are Thomist/Aristotelian Mitigated Realism, or Acosmic Monism; anything in between is muddleheaded sophistry.

Anyway, steve40, Descartes was not saying that his thought was the cause of his existence; not even he was that dim. He was saying that, since he seemed to be experiencing things, and thinking, he must exist to be doing it.

Which, mansizedtarget, your spin on Anatmaism vis-a-vis neuroscience, would deny. :smiley:

And hang on a dang minute, you accused Aristotelianism of Cartesian dualism while defending Descartes’s metaphysics! The position you were so quaintly mocking, that the mind is wholly separate from the brain, is entirely foreign to Aristotle–but it is the position of your precious Descartes. As well attack Camus as a racist, on the basis of Heidegger!

Holy mackerel, what did you do at school?

I am a Catholic. I long considered myself an Aristotelian. I focused my studies on political phiosophy and ethics.

Believe it or not, not everyone who disagrees with you is stupid. Surely you wouldn’t call Nietzsche or Hume or Bacon or Wittgenstein stupid, even though they’d ask and answer the questions I ask above in a very extreme way. I am asking these questions because, while I’m very impressed by and find something appealing and natural in Aristotle’s ethics and politics, I find its foundations in his physics and metaphysics shaky. Stringing together conclusory assertions without rigor, as you do above, is not particularly helpful in answering these concerns and criticisms.

Anyway, the basic questions I asked above, which remain unanswered, amounts to the basic modernist, empiricist critique of classical metaphysics, i.e., the critique of Hume (and to a lesser extent Descartes and also Nietzsche) in particular. This view does away with much of metaphysics (admittedly) and also with the classical division of causation replacing it instead with a moderate empiricist view of causation as the regular correlation of events, yet it still gets along fine, makes useful predictions in natural science, and its progeny have more explanatory power of the material world than the old philosophy. The real question is still for me how do you know Aristotle’s metaphysics is right, and how would one prove it true or otherwise?

The old Aristotelian system posited a mind that was distinct from the brain/material world/body, even if “mind” and “will” was seen as a product or activity of the brain–not quite sure classical philosophy even conceded the last point.

The “mind” concept is largely coextensive with the Catholic use of the word soul,i.e., reason and will. If mind is really just the complicated activity of the brain and lacks a nonmaterial (i.e., eternal) essence, this seems to me a major threat to the integrity of Catholic teaching as presently constituted.

My question remains how should this concept of mind and soul be modified in light of the fact that actual, practical phenomena formerly attributed to the mind can be adequately and completely explained as epiphenomena of the brain, i.e., various mental illnesses that manifest in behaviors like OCD, addictions, personality disorders etc. The mind is not and never was seen as an abstract entity, outside the material world, devoid of visible consequences and effects. I don’t think we disagree on this.

But take something as simple as a criminal misbehavior; if it can be adequately explained by chemical imbalances and frontal lobe deformations, what explanatory role remains for the mind/soul?

Throwing up a bunch of conclusory Aristotelian metaphysics won’t make this problem go away, and it’s the reason classical philosophy was displaced so thoroughly by the insights, method, and deliberately vague metaphysics (i.e., logial positivism) that underly modern science. Philosophers can worry about whether we can trust our senses; scientists, meanwhile, are curing cancers and making atomic bombs.

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