Archive for the ‘Compendium Theologiae’ Category

CT 92: Refutation of the Preceding Objections

Monday, July 20th, 2009

Last time, we got some objections to the “unicity of the soul”; now we get the answers to those objections. Thomas says,

To set aside such quibbles, we should reflect that, in material things, one species surpasses another in perfection, in the way that, in numbers, species are diversified by adding one to another. Whatever perfection is found in lifeless bodies, plants also possess, and more besides. Again, whatever plants have, animals have too, and something else in addition. And thus we proceed until we come to man, the most perfect of bodily creatures. All that is imperfect is related as matter to what is more perfect. This is clear in the various classes of beings.

A plant is body that has life. It’s not like you can divide a plant into two pieces, one that’s the body and one that’s the life, like dividing a car into an engine and everything else. As you move down through the genera, each kind of body gets richer and richer, not composed of more and more parts.

The elements constitute the matter of bodies that are composed of similar parts; and again, bodies having similar parts are matter with respect to animals. And this is likewise to be observed in one and the same being. Among natural things, that which is endowed with a higher degree of perfection has, in virtue of its form, whatever perfection is found in lower nature, and in virtue of the same form has, besides, its own added perfection.

I think this is what I just said, though not so nicely.

Through its soul, the plant is a substance, and is corporeal, and besides is an animated body. Through its soul, an animal has all these perfections, and moreover is sentient. In addition to all this, man is intelligent through his soul. Thus, in any object, if we consider what pertains to the perfection of a lower grade of being, this will be material when compared with what pertains to the perfection of a higher grade. For example, if we observe that an animal has the life of a plant, this life is in some fashion material with respect to what pertains to sensitive life, which is characteristic of an animal.

“Material” and “formal” are two words that I boggle at once in a while. I understand what they mean in certain contexts, and then Thomas goes and uses them in some way that I don’t get. I assume that they have a wider meaning than I really get. Let’s see if I can tease it out.

A species, such as “animal”, is, of course, a form—or, at least, includes one in its definition. And “animal” represents something added to “plant”, as a form is added to matter and makes it something new, or gives it a new quality.

Genus, of course, is not matter, for then it would not be predicated of the whole. But it is something derived from matter; for the designation attaching to a thing in terms of what is material in it, is its genus.

I remember this from De Ente et Essentia (or perhaps it was Porphyry) but it made more sense then.

Specific difference is derived from the form of a thing in the same way. This is the reason why living or animated body is the genus of animal, and sensitive is the specific difference that constitutes it. Similarly, animal is the genus of man, and rational is the difference that constitutes him. Therefore, since the form of a higher grade of being comprises within itself all the perfections of a lower grade, there is not, in reality, one form from which genus is derived, and another from which specific difference is derived. Rather, genus is derived from a form so far as it has a perfection of lower degree, and specific difference is derived from the same form so far as it has a perfection of higher degree.

OK, now, this makes sense. No genus gives a thing form; no specific difference gives a thing form; only a species with actual individuals gives anything form.

Thus, although animal is the genus of man and rational is the specific difference constituting him, there need not be in man a sensitive soul distinct from the intellectual soul, as was urged in the first argument.

The first argument argued that an animal, having a sensitive soul, was in potency with respect to a rational soul, that is, that a rational soul is something that could be added. But “rational” is a specific difference, not a form; it can’t be added like that.

This indicates the solution of the second difficulty.

Which was that the intellect has no bodily organ whereas the sense does; thus, the intellect is separated from the body and the sense is not, and one thing can’t be both separated and unseparated.

As we have pointed out, the form of a higher species comprises within itself all the perfections of lower classes of being. We must note, however, that the species of a material being is higher in proportion as it is less subject to matter. And so the nobler a form is, the more it must be elevated above matter.

Hence the human soul, which is the noblest of all forms of matter, attains to the highest level of elevation, where it enjoys an activity that is independent of the concurrence of corporeal matter. Yet, since the same soul includes the perfection of lower levels, it also has activities in which corporeal matter shares. However, an activity is exercised by a thing in accordance with the thing’s power. Therefore the human soul must have some powers or potentialities that are principles of activities exercised through the body, and these must be actions of certain parts of the body. Such are the powers of the vegetative and sensitive parts. The soul has also certain powers that are the principles of activities exercised without the body. Such are the powers of the intellectual part, whose actions are not performed by any organs. For this reason both the possible intellect and the agent intellect are said to be separate; they have no organs as principles of their actions, such as sight and hearing have, but inhere in the soul alone, which is the form of the body. Hence we need not conclude, from the fact that the intellect is said to be separate and lacks a bodily organ, whereas neither of these is true of the senses, that the intellectual soul is distinct from the sensitive soul in man.

The intellect is separate from the body, but the soul as a whole is not. In animals, you might say that the soul is coextensive with the body, and contains in; in humans, it’s as though the soul extends a little bit beyond the body.

This also makes it clear that we are not forced to admit an intellectual soul distinct from the sensitive soul in man on the ground that the sensitive soul is corruptible whereas the intellectual soul is incorruptible, as the third objection set out to prove. Incorruptibility pertains to the intellectual part so far as it is separate. Therefore, as powers that are separate, in the sense mentioned above, and powers that are not separate, are all rooted in the same essence of the soul, there is nothing to prevent some of the powers of the soul from lapsing when the body perishes, while others remain incorruptible.

You can’t sense without senses…but it isn’t that the soul of a dead person lacks the power of sense, it just lacks the ability to make use of it. This is what makes the doctrine of the Resurrection of the Body so exciting; we’ll have new bodies, better than before, and all of our faculties will work better than ever.

The points already made lead to a solution of the fourth objection.

Which was that a human fetus is first a living body but not sentient, and then sentient but not rational, and then rational, and so these faculties are added as accidents to a base substance.

All natural movement gradually advances from imperfect to perfect. The same quality is receptive of greater and less; hence alteration, which is movement in quality, being unified and continuous in its progress from potency to act, advances from imperfect to perfect. But substantial form is not receptive of greater and less, for the substantial nature of each being exists indivisibly. Therefore natural generation does not proceed continuously through many intermediate stages from imperfect to perfect, but at each level of perfection a new generation and corruption must take place. Thus in the generation of a man the fetus first lives the life of a plant through the vecetative soul; next, when this form is removed by corruption it acquires, by a sort of new generation, a sensitive soul and lives the life of an animal; finally, when this soul is in turn removed by corruption, the ultimate and complete form is introduced. This is the rational soul, which comprises within itself whatever perfection was found in the previous forms.

With all due respect, I think Thomas must be wrong, here. He would have a human develop in stages, losing one soul then gaining another twice in the womb. It seems to me more likely that a human embryo gains a rational soul immediately, and then grows into it. The intellect requires sense phantasms to work upon, and it can’t get them until the body’s senses develop; but just as the soul of a dead man cannot exercise its sense, so the soul of an embryo cannot.

CT 91: Arguments Advanced to Show A Multiplicity of Souls in Man

Friday, July 17th, 2009

Thomas once again departs from the script with this chapter; having asserted that each man has a single soul, he’s giving the objections in this chapter and the answers to the objections in the next.  If there’s no feeling of closure in this post, blame Thomas, not your humble scribe.

Thomas begins,

Certain considerations seem opposed to our doctrine. In the first place, specific difference is to genus what form is to matter. Animal is the genus of man, and rational is the difference that makes man what he is. Accordingly, since animal is a body animated by a sensitive soul, it seems that a body animated by a sensitive soul is still in potency with respect to the rational soul. Thus the rational soul would be distinct from the sensitive soul.

Hmmm.  Form makes matter what it is; matter that does not possess a particular form (but can) is in potency with respect to that form. My son can dye his hair blue, but he has not yet done this; his hair is blue in potency.  Just as blueness can be added to my son’s hair to make it blue in act, the specific difference “rational” can be added to the genus “animal” to make it “man” in act.  Thus, “animal” is in potency with respect to “rational”…and rationality is an accident added to an animal substance.  Hence, the rational soul must be distinct.  The error, I think, is that the objector is using an invalid analogy.  We’ll see.

Moreover, the intellect does not possess a bodily organ. But the sensitive and nutritive powers do possess bodily organs. Hence it seems impossible for the same soul to be both intellectual and sensitive, because the same thing cannot both be separated and not separated from another thing.

That’s clear enough.  But must two things which are “not separated” be coextensive?  I don’t see why they should be.

Furthermore, the rational soul is incorruptible, as was shown above. On the other hand, the vegetative and the sensitive souls are corruptible, as they are acts of corruptible organs. Therefore the rational soul is not the same as the vegetative and the sensitive souls, for the same thing cannot be both corruptible and incorruptible.

The problem here, I think, is the lack of a distinction between souls on the one hand and faculties on the other.  The vegetative soul has the vegetative faculty: plants can take in nutrition and grow.  The sensitive soul has the vegetative faculty and the sensitive faculty.  The rational soul has the vegetative, sensitive, and rational faculties.

Thus, it’s not that man has a vegetative soul, a sensitive soul, and a rational soul; rather, he possesses all three faculties in one rational soul.  The first two faculties require corruptible organs, that is, material organs that can die; the last does not.

Besides, in the generation of man the life conferred by the vegetative soul appears before the fetus is observed to be an animal from its sense activity and motion; and this same being is discerned to be an animal through its sense activity and movement before it has an intellect. Therefore, if the soul by which the fetus first lives the life of a plant, then the life of an animal, and thirdly the life of a man, is the same, it would follow that the vegetative, sensitive, and rational principles come from an outside source, or else that the intellectual soul arises from the energy in the semen. Both of these alternatives are inadmissible. On the one hand, since the operations of the vegetative and sensitive soul are not exercised apart from the body, their principles cannot be without a body. On the other hand, the operation of the intellectual soul is exercised without a body; and so, apparently, no bodily energy can be its cause. Therefore the same soul cannot be vegetative, sensitive, and rational.

One can argue with St. Thomas’ notion of fetal development, but I’ll slide past that.  The argument here appears to be that since the vegetative and sensitive souls require bodily organs, they are caused by the body; and yet, being immaterial, the rational soul, or intellect, cannot be caused by the body; and since they have two distinct causes, they must be two distinct things.  But the body is not the principle of the soul; the soul is the principle—the form—of the body. 

I suppose you could think of this chapter as a sort of quiz, with essay questions.  We’ll see how I did when I blog the next chapter.

CT 90: Unicity of the Soul

Wednesday, July 15th, 2009

All of a man’s faculties that are rooted in the soul are rooted in the man’s one and single and only soul, because a man can have no more than one soul. So quoth St. Thomas. But why? Now Thomas explains.

That there cannot be several souls in one body is proved as follows. The soul is evidently the substantial form of any being possessing a soul, because a living being is constituted in genus and species by its soul. But the same thing cannot have several substantial forms. A substantial form differs from an accidental form in this, that a substantial form causes a particular thing simply to be, whereas an accidental form is added to a particular being already constituted as such, and determines its quality or quantity or its mode of being. Hence, if several substantial forms belong to one and the same thing, either the first of them causes it to be this particular thing or it does not. If it does not, the form is not substantial; if it does, then all the subsequent forms accrue to what is already this particular thing. Therefore none of the subsequent forms will be the substantial form, but only some accidental form.

Clearly, therefore, one and the same thing cannot have several substantial forms; and so one and the same person cannot have several souls.

I am a human being, a rational animal, because I have a human soul. If I didn’t have a human soul, I’d be something else. My soul is my substantial form, that which makes me a substance; and I can have only one of those, so I can have only one soul.

However, there’s clearly more going on in the sentence I bolded than meets the eye.

Furthermore, it is evident that a man is said to be living because he bas a vegetative soul, that he is called an animal because he has a sensitive soul, and that he is a man because he has an intellectual soul. Consequently, if there were three souls in man, namely, vegetative, sensitive, and rational, man would be placed in a genus because of one of his souls, and in a species because of another. But this is impossible. For thus genus and specific difference would constitute, not what is simply one, but what is one per accidens, or a sort of conglomeration, such as musical and white; but such is not a being that is simply one. Accordingly a man can have only one soul.

A species defines one kind of thing; it is the essence of the things that it is the species of. It is, in fact, the form the individual members of the species. As such, it needs to be one, not three.

Someday maybe I’ll have a deep understanding of genus, species, and so forth. I know enough to understand what Thomas is saying, but not enough to see all of the implications.

CT 89: Radication of All Faculties in the Essence of the Soul

Monday, July 13th, 2009

At last, we have a blessedly short chapter, though that’s an interesting word at the head: “radication”. I think it means “the rooting”. Anyway, Thomas says,

Not only the agent intellect and the possible intellect, but also all the other powers that are principles of the soul’s operations, are united in the essence of the soul. All such powers are somehow rooted in the soul. Some of them, indeed, such as the powers of the vegetative and sensitive parts, are in the soul as in their principle, but in the composite as in their subject, because their activities pertain to the composite, not to the soul alone; for power and action belong to the same subject. Some of them, on the other hand, are in the soul both as principle and as subject, for their operations pertain to the soul apart from any bodily organ. These are the powers of the intellectual part. But a man cannot have several souls. Accordingly all the powers must pertain to the same soul.

Remember that plants and animals have souls as well, that is, they are alive, they have “breath”, which is what the Greek word for “soul” means. A plant’s faculties of growth and ingestion are rooted in the plant’s life, in its soul. An animal adds the faculties of movement and sense. But these faculties, though rooted in the plant’s or animal’s soul, involve the body as well. It is the body that grows, and the body that senses. Man has a rational soul: he has the faculties of the plants and animals, but adds intellect, which is not only rooted in the soul but is wholly contained with it.

But a man cannot have several souls, so all of these powers must be rooted in one and the same soul, the only one he’s got. Why? That’s the next chapter.

CT 88: The Way These Two Faculties Are United In The Same Essence Of Soul

Sunday, July 12th, 2009

So, the possible intellect and the agent intellect are united in one soul. But wait! There’s another problem:

We have still to consider how this union is possible. Some difficulty may seem to arise in this matter. The possible intellect is in potency with respect to all that is intelligible, whereas the agent intellect causes what is intelligible in potency to be intelligible in act, and so must be related to what is intelligible as act to potency. But the same thing, seemingly, cannot be both in potency and in act with respect to the same object. Thus it would appear that the possible intellect and the agent intellect cannot be united in the same substance of the soul.

How can one thing, one human soul, be both in potency and act with respect to a single object?

I confess, this is not a matter of great concern to me, but I resolved when I began to work all of the way through the Compendium Theologiae, without skipping anything, so I’ve got to go through it. That’s no reason that you have to. In this particular case, I’m just going to let Thomas speak for himself, and highlight a couple of interesting points in the discussion.

This doubt is easily resolved if we examine how the possible intellect is in potency with respect to intelligible objects, and how the agent intellect renders them actually intelligible. The possible intellect is in potency with regard to intelligible objects in the sense that it does not contain within its nature any determinate form of sensible things. In the same way the pupil of the eye is in potency with regard to all colors. To the extent, then, that phantasms abstracted from sensible things are likenesses of definite sensible things, they are related to the possible intellect as act to potency. Nevertheless the phantasms are in potency with regard to something that the intellectual soul possesses in act, namely, being as abstracted from material conditions. And in this respect the intellectual soul is related to the phantasms as act to potency. No contradiction is involved if a thing is in act and potency with regard to the same object according to different points of view. Thus natural bodies act upon each other and are acted upon by each other, for each is in potency with respect to the other. The same intellectual soul, therefore, can be in potency with regard to all intelligible objects and nevertheless, without any contradiction, can be related to them as act, if both a possible intellect and an agent intellect are acknowledged in the soul.

There’s more than one way to look at most things, and intelligible objects are surely one of them. You can be in potency with respect to it in one way, and in act with respect to it in another. How can I have my cake in potency and act at the same time? I can have it before me in act, and have it in my stomach in potency. Once I have eaten it, I have in my stomach in act, and (if it was a large cake, and I ate it all) I can have it before me in potency.

This will be seen more clearly from the way the intellect renders objects actually intelligible. The agent intellect does not render objects actually intelligible in the sense that the latter flow from it into the possible intellect. If this were the case, we would have no need of phantasms and sense in order to understand. No, the agent intellect renders things actually intelligible by abstracting them from phantasms; just as light, in a certain sense, renders colors actual, not as though it contained the colors within itself, but so far as it confers visibility on them. In the same way we are to judge that there is a single intellectual soul that lacks the natures of sensible things but can receive them in an intelligible manner, and that renders phantasms actually intelligible by abstracting intelligible species from them. The power whereby the soul is able to receive intelligible species is called the possible intellect, and the power whereby it abstracts intelligible species from phantasms is called the agent intellect. The latter is a sort of intelligible light communicated to the intellectual soul, in imitation of what takes place among the higher intellectual substances.

As usual, Thomas puts things better than I do. I like this description of the possible and agent intellect, and I especially like the description of the agent intellect as a “sort of intelligible light communicated to the intellectual soul…” We often say that a clear explanation casts light on a dim subject. The divine light of reason shines upon us and casts light on the objects we sense, allowing us to abstract universal concepts from them. It is by the divine light of reason that I can see that animal, and know that it is an animal, and not just any animal, but a dog.

Why is this in imitation of the angels, the “higher intellectual substances”? Because, according to Thomas, God in a sense pre-equips them with the intelligible species that they need. They have no senses; they do not perceive. Rather, their intellects apprehend directly. They do not abstract universals from sensible objects, but just know them.

What a peculiar creature Man is, to be sure.

CT 87: The Possible Intellect and the Agent Intellect as Residing in the Essence of the Soul

Thursday, July 9th, 2009

So we’ve shown that each man has one possible intellect and one agent intellect, and that these things are united to man as form. Consequently, says Thomas,

Since the agent intellect and the possible intellect are united to us as form, we must acknowledge that they pertain to the same essence of the soul.

I do not understand what he means by “the same essence of the soul.” The essence of something is what it is. The essence of a dog is to be a dog. The essence of a man is to be a rational animal. Does a man’s soul have its own essence apart from the essence of a man? But let’s move on. Thomas then says,

Whatever is formally united to another thing, is united to it either in the manner of a substantial form or in the manner of an accidental form. If the possible intellect and the agent intellect were united to man after the fashion of a substantial form, we would have to hold that they share in the one essence of that form which is the soul, since one thing cannot have more than one substantial form.

Right. If a man’s intellect is part of his substantial form, then it part of his soul, for his soul is his substantial form.

On the other hand, if they are united to man after the fashion of an accidental form, neither of them, evidently, can be an accident of the body. Besides, the fact that their operations are performed without a bodily organ, as we proved above, shows that each of them is an accident of the soul. But there is only one soul in one man. Therefore the agent intellect and the possible intellect must inhere in the one essence of the soul.

In other words, the agent and possible intellect are united with the soul either substantially or accidentally, not with the body as such.

Furthermore, every action that is proper to a species proceeds from principles that emanate from the form which confers the species. But the action of understanding is an operation proper to the human species. Therefore the agent intellect and the possible intellect, which are principles of this action, as has been shown, emanate from the human soul, whence man has his species. However, they do not issue from the soul in such a way as to extend to the body, because, as we have said, the operation in question takes place independently of a bodily organ. Since, therefore, action pertains to the same subject as does potency, the possible intellect and the agent intellect inhere in the one essence of the soul.

I am rational because I am a man, a rational animal. It is part of being human, part of the very definition of being human, to be rational. It is my intellect that makes me rational: I must necessarily have one. But the intellect is immaterial; so it must “inhere in the one essence of the soul.”

There’s clearly a distinction I’m missing here; I don’t understand why Thomas insists on “inhere in the one essence of the soul” rather than just “inhere in the soul”.

CT 86: The Agent Intellect Not One In All Men

Wednesday, July 8th, 2009

Thomas has just shown that every man has his own possible intellect; now he’s going to show that every man has his own agent intellect as well:

There were also some philosophers who argued that, even granting the diversification of the possible intellect in men, at any rate the agent intellect was but one for all. This view, while less objectionable than the theory discussed in the preceding chapter, can be refuted by similar considerations.

So what’s the difference between the possible intellect and the agent intellect? As I understand it—and I’m not at all sure that I really do understand it—the possible intellect is like the memory of the intellect. As I learn about more and more things, the intelligible species by which I understand them get squirreled away in the possible intellect. It’s called the possible intellect, because it’s the collection of concepts that it’s possible for me to bring to mind. I understand this vast collection of intelligible species in potency, but not in actuality.

The agent intellect is so called because it is the agent—the efficient cause—of my understanding something. It does two things: first, when I bring a concept to mind, the agent intellect brings it from potency to act in my mind; and second, when I learn to understand a new thing it is the agent intellect that abstracts the essence of the thing, its species, from it and makes it intelligible.

Or, as Thomas says,

The action of the possible intellect consists in receiving the objects understood and in understanding them. And the action of the agent intellect consists in causing things to be actually understood by abstracting species. But both these functions pertain to one particular man. This man, for example, Socrates or Plato, receives the objects understood, abstracts the species, and understands what is abstracted. Hence the possible intellect as well as the agent intellect must be united to this man as a form. And so both must be numerically multiplied in accord with the number of men concerned.

In short, without going into a detailed argument as he did in Chapter 85, Thomas simply points out that when I understand something it’s I who understand it, and when you understand something it’s you who understand it, and to say that we might be sharing a single intellect to do the job is just silly.

Nevertheless, Thomas does go on to say why it makes sense:

Moreover, agent and patient must be proportionate to each other. Examples are matter and form, for matter is reduced to act by an agent.

The agent is the efficient cause, the thing making a change occur, and the “patient,” I take it, is the thing acted upon. The agent intellect acts upon the possible intellect, and hence they must be proportionate to each other. I believe that he means “proportionate” in the same way that we’d might say that an object is disproportionate to a container that’s too small for it. They have to fit together.

This is why an active potency of the same genus corresponds to every passive potency; for act and potency pertain to one genus. But the agent intellect is to the possible intellect what active potency is to passive potency, as is clear from this discussion. Hence they must both pertain to one genus. Therefore, since the possible intellect has no separate existence apart from us, but is united to us as a form and is multiplied according to the number of men, as we have shown, the agent intellect must likewise be something that is united to us as a form, and must be multiplied according to the number of men.

OK, now here are a couple of terms I’ve not run into before: “active potency” and “passive potency”. I’ll guess that a thing has an active potency if it’s capable of doing something but isn’t currently doing it, and that a thing has passive potency if something can be done to it but it isn’t currently being done. Thus, I can pick up that ball and throw it, and that ball can be picked up and thrown, and gosh, wow, sure enough, the active potency and the passive potency are proportionate to each other. They fit. I suppose one could say that they pertain to one genus.

So anyway, the same is true of the agent intellect and the possible intellect. The agent intellect is capable of bringing a concept to mind, and the possible intellect can provide one. And so they must both pertain to one genus, which means (I’m not entirely sure why; I think Thomas might be skipping a few steps) that they must both be united to a man as a form.

So we’ve each got a possible intellect and an agent intellect of our very own.

CT 85: Unity of the Possible Intellect (Part IV)

Tuesday, July 7th, 2009

Now we’ll discuss Thomas’ response to the objections covered in Part II. (The background for this chapter is in Part I.)

The arguments advanced to support the contrary view are easily answered.

The first objection is that if each man has his own intellect, then each man has his own set of concepts by which he understands the things he perceives; and consequently these concepts are not, in fact, universals. But universals are precisely what we understand, and so consequently each man cannot have his own intellect.

The first argument has many defects. First of all, we concede that the same thing may be understood by all. By the thing understood I mean that which is the object of the intellect. However, the object of the intellect is not the intelligible species, but the quiddity of the thing. The intellectual sciences are all concerned with the natures of things, not with intelligible species; just as the object of sight is color, not the species of color in the eye. Hence, although there may be many intellects belonging to different men, the thing understood by all may be but one; just as a colored object which many look at is but one.

I see a dog. The concept, or intelligible species, “dog” appears in my mind. But I do not understand this concept, “dog”; rather, I understand that this dog standing before me is a dog. Concepts are like pointers in a computer language: the thing of interest is not the pointer itself, but the data at which it points. Thus, when you and I see a dog, we each have our own concept; but those concepts both point at the same thing, viz, Dogginess, what it is to be a dog.

This next bit speaks to a passage I didn’t understand in the first objection; if you go back to Part II, you’ll find it:

Secondly, the consequence does not necessarily follow that, if a thing is individual, it is understood in potency and not in act. This is true only of things that are individuated by matter. Of course, what is understood in act must be immaterial. Accordingly immaterial substances, even though they may be individuals existing by themselves, are understood in act. The same holds for intelligible species, which are immaterial; although they differ numerically in me and in you, they do not on that account lose their property of being intelligible in act. The intellect that understands its objects by means of them reflects upon itself, thereby understanding its very action of understanding as well as the species whereby it understands. Moreover, we should realize that, even if we admit but one intellect for all men, the difficulty is still the same. There would still remain many intellects, because there are many separate substances endowed with intelligence. And so it would follow, pursuing our adversaries’ line of reasoning, that the objects understood would be numerically different, hence individual and not understood in first act. Obviously, therefore, if the objection under discussion had any cogency, it would do away with a plurality of intellects simply as such, and not merely in men. Since this conclusion is false, the argument manifestly does not conclude with necessity.

Since I didn’t understand this part of the objection, I don’t really understand the answer. But it’s interesting to note that the objection is really an argument that there’s only one Intellect, period, not that there’s only one Intellect for all men. If the objection were cogent, then all men, angels, and God would share a single intellect.

The second objection is that each intellectual substance must belong to a separate species. Thus, if you and I have distinct intellects, we must belong to different species. But this is an unfair extrapolation from the case of angels.

The second argument is readily answered, if we but consider the difference between an intellectual soul and separate substances. In virtue of its specific nature, the intellectual soul is meant to be united to some body as the latter’s form; the body even enters into the definition of the soul. For this reason, souls are numerically differentiated according to the relation they have to different bodies; which is not the case with separate substances.

By “separated substances”, Thomas means angels, immaterial spirits. But there’s a difference between the human soul and an angel, even though both are immaterial and intellectual: it is part of the human soul’s nature to have a body, and it is the relation of the soul to the body that makes human souls distinct. In short, people aren’t angels.

The third objection is that if souls are made distinct by the possession of a body, then when the body dies nothing remains to distinguish between two souls. Consequently, there can be only one soul among all men.

This also indicates how the third argument is to be answered. In virtue of its specific nature, the intellectual soul does not possess the body as a part of itself, but has only an aptitude for union with the body. Therefore it is numerically differentiated by its capacity for union with different bodies. And this remains the case with souls even after their bodies have been destroyed: they retain a capacity for union with different bodies even when they are not actually united to their respective bodies.

That is, my body is not part of my soul; but my soul has a particular aptitude to be united with my particular body. It’s as though the soul and body interlock like a plug in a socket; each person’s socket is different. Even when the body dies and the plug is removed from the socket, my soul’s plug is different than yours.

And that wraps up our discussion of the (lack of) unity of the possible intellect. Next, we get to look at the agent intellect.

CT 85: Unity of the Possible Intellect (Part III)

Sunday, July 5th, 2009

I began discussing this chapter of St. Thomas’ Compendium Theologiae back around the end of April; finally, two months later, I’m getting back to it. In order to understand this post you’ll want to revisit Part I and Part II of the discussion.

I’ve just re-read them myself, in preparation to continue, and I think they hold up OK. There’s one point I’d like to clarify. In Part I, I say

And then you’ve got humans, who are individuated by matter, as animals are, but have an intellectual (and hence immaterial) soul, as angels do.

This is not quite right: an angel does not have an intellectual and immaterial soul; rather, an angel is an intellectual and immaterial spirit. The human soul is also intellectual and immaterial spirit.

But this is a nit.

In Part II, Thomas speaks of those who would say that all men share a single Soul. Having described that position, he now goes on to explain how every man can have a unique soul while remaining members of the one species.

The absurdity of this whole position is easily perceived.


To make this clear, let us proceed as one would proceed against those who deny fundamental principles. That is, let us establish a truth that simply cannot be denied. Let us suppose that this man, for example, Socrates or Plato, understands. Our adversary could not deny that the man understands, unless he knew that it ought to be denied. By denying he affirms, for affirmation and denial are intelligent actions.

Thomas is, I gather, trying to prove that man can understand to one who denies it. He posits that Socrates can understand. The denier cannot rationally deny that Socrates understands unless the denier has a good reason. But if denier has a good reason, that reason is an act of understanding! Therefore, the denier must either affirm that Socrates understands or, in denying it, affirm that he himself understands. Thus, it is possible for a man to understand.

(Remember that for Thomas, to understand is to know intellectually. If I see a dog, the appearance of the dog is present to my Sense: I perceive the dog, I have a perception. When I recognize that I perceive a dog, the concept dog is now present to my intellect, and I understand that this object before me is a dog.)

If, then, the man in question understands, that whereby he formally understands must be his form, since nothing acts unless it is in act.

There is act, that which is, and potency, that which could be. I am here; I could be there. I am hungry; I could be full. I am thinking; I could be asleep. Anything that I actually am, or actually do, involves bringing something potential into actuality. That’s the first thing. And the second thing is, actuality always involves form.

When I understand something in actuality, rather than just potentially, I am acting; and that by which I understand, as a formal cause of my understanding, is my form.

Hence that whereby an agent acts, is his act; just as the heat by which a heated body causes warmth, is its act. Therefore the intellect whereby a man understands is the form of this man, and the same is true of another man.

My intellect is my form; and your intellect is your form.

But the same numerical form cannot belong to numerically different individuals, for numerically different individuals do not possess the same existence; and yet everything has existence by reason of its form. Accordingly the intellect whereby a man understands cannot be but one in all men.

What makes me me is mine; and what makes you you is yours. These are two separate, numerically distinct things. What makes me me is my form, and as shown above my form is my intellect. The same applies to you. Thus, my intellect and your intellect are distinct.

Perceiving the force of this difficulty, some endeavor to find a way of escaping it. They say that the possible intellect, of which there was question above, receives the intelligible species by which it is reduced to act. These intelligible species are, in some way, in the phantasms. Hence the possible intellect is continuous and is joined to us so far as the intelligible species is both in the possible intellect and in the phantasms that are in us. It is thus that we are able to understand through the agency of the possible intellect.

Now things get a little difficult. (Now? Now, he says?) We need to review some background.

Every man has Intellect and Sense. Sense is the faculty with which we sense the outside world through our sight, smell, taste, touch, and hearing; it’s also the faculty whereby we imagine things of this sort. When I see my son, there is an image in my Sense. When I picture the face of my son, I am using my imagination: I am bringing forth an image from my memory. Again, the image is in my Sense. This kind of image, however derived, and whichever senses are involved, is what Thomas means by a “phantasm”.

Now, the Sense belongs to our animal nature: every animal has it to a greater or lesser degree. It is, consequently, an aspect of our material bodies, and in particular of our brains.

Our Intellect, as we’ve said before, is immaterial: non-human animals have no intellect, and cannot be said to be rational.

Now, there is a link between the Sense and the Intellect. We see the world, resulting in phantasms in our Sense. Our Intellect apprehends the natures of these phantasms, resulting in intelligible species in our possible intellect.

At this point, you should probably go back and re-read the last quoted passage.

There are those who insist that Intellect is one, that all humans share one Intellect. But our Intellect is our form, that which gives us existence; we must each have our own. Those who insist that the intellect is one try to get around this by pointing out the link between the Intellect and the Sense. The intelligible species understood by the Intellect are somehow present in the phantasms perceived by the Sense. This roots the shared Intellect in the individual man’s Sense, and makes it appear individuated without its really being so.

So they say, but Thomas strongly disagrees:

Unfortunately for this solution, it is utterly valueless.

This is a remarkably strong statement for Thomas; he’s usually more understated.

In the first place, the intelligible species, as it exists in the phantasms, is a concept only in potency; and as it exists in the possible intellect, it is a concept in act. As existing in the possible intellect, it is not in the phantasms, but rather is abstracted from the phantasms. Hence no union of the possible intellect with us remains.

We understand intelligible species, or (as we would say today) concepts. The concepts are present in the phantasms in potency only, not in act; the Intellect brings them into act by abstracting them from the phantasms. If the Intellect is one and shared by all men, then “no union of the possible intellect with us remains.”

Secondly, even granting that there may be some sort of union, this would not suffice to enable us to understand. The presence of the species of some object in the intellect does not entail the consequence that the object understands itself, but only that it is understood; a stone does not understand, even though a species of it may be in the possible intellect. Hence, from the fact that species of phantasms present in us are in the possible intellect, it does not follow that we thereupon understand. It only follows that we ourselves, or rather the phantasms in us, are understood.

If I perceive a stone, a phantasm of that stone appears in my Sense. And if there is a sufficient union of my Sense with this “shared intellect”, as Thomas denies, that the concept Stone appears in the shared intellect, this means that the Stone is understood by the shared intellect; it does not mean that I, an individual, am the one who understands Stone.

This will appear more clearly if we examine the comparison proposed by Aristotle in Book III of De anima [7, 431 a 14], where he says that the intellect is to phantasm what sight is to color. Manifestly, the fact that the species of colors on a wall are in our vision does not cause the wall to see, but to be seen. Likewise, the fact that the species of the phantasms in us come to be in the intellect, does not cause us to understand, but to be understood.

If the intellect that understands my phantasms is not mine, then I am understood, but I cannot say that I understand.

Further, if we understand formally through the intellect, the intellectual action of the intellect must be the intellectual action of the man, just as the heating action of fire and of heat are the same. Therefore, if intellect is numerically the same in me and in you, it follows that, with respect to the same intelligible object, my action of understanding must be the same as yours, provided, of course, both of us understand the same thing at the same time. But this is impossible, for different agents cannot perform one and the same numerical operation. Therefore it is impossible for all men to have but a single intellect.

My understanding is my understanding, and your understanding is yours. We can both understand the same thing, but not by the same act.

Consequently, if the intellect is incorruptible, as has been demonstrated many intellects, corresponding to the number of men, will survive the destruction of their bodies.

Thus, every man must have his own Intellect. And since the Intellect is incorruptible, then when men die their Intellects remain.

I think I understood some of that, but certainly not all of it.

In the next part, we’ll look at Thomas’ answer to the objections listed in Part II.

CT 85: Unity of the Possible Intellect (Part II)

Wednesday, April 29th, 2009

Some, Thomas tells us, would conclude from the immaterial nature of the possible intellect that all men must share a single intellect, and hence a single soul. As he says,

An objector may say: the intellect is indeed incorruptible, but there is only one intellect in all men; and so what remains after the corruption of all men is but one. That there is only one intellect for all men, the objector may continue, can be established on many grounds.

So much we said yesterday.

First, on the part of the intelligible species. If I have one intellect and you have another, there will have to be one intelligible species in me and another in you, and consequently there will be one object that I understand and another that you understand. Hence the intelligible species will be multiplied according to the number of individuals, and so it will not be universal but individual. The conclusion would then seem to follow that it is understood not in act, but only in potency; for individual species are intelligible in potency, not in act.

When I apprehend an object, what I have in my possible intellect is its intelligible species. And indeed, this intelligible species will be multiplied by the number of individuals. So how can the intelligible species be a universal? (The answer, as we will see, is that it isn’t, and that’s OK.) The meaning of the italicized sentence eludes me tonight.

Moreover, since the intellect, as we have seen, is a substance subsisting in its own being, and since intellectual substances that are numerically many do not belong to one species, as we have also seen, it follows that if I have one intellect and you have another that is numerically different, the two must differ specifically. And so you and I would not belong to the same species.

I talked about this yesterday. To be numerically many, the object says, two beings must either be of different species, as angels are, or of the same species and distinguished by having different matter, as animals are. Thomas is going to choose a third option.

Furthermore, since all individuals share in one specific nature, there must be something besides specific nature whereby individuals may be distinguished from one another. Accordingly, if there is one specific intellect in all men, but many intellects that are numerically distinct, something must be found that will make one intellect differ numerically from another. This cannot be anything pertaining to the substance of the intellect, since the intellect is not composed of matter and form. Consequently any difference that might be admitted, on the part of the substance of the intellect, would be a formal difference that would cause diversity in the species. The only possibility left is that the intellect of one man cannot differ numerically from the intellect of another man except by reason of the diversity of their bodies. Therefore, when the various bodies corrupt, it seems that only one intellect, and not a plurality of intellects, would remain.

Something distinguishes one man from another, and it appears to be the possession of a body. For my intellect to be distinct from yours, while being immaterial, would seem to make us be of two different species, which is not the case. Thus, when I die and you die, there’s nothing to distinguish the intellect that remains. I take it that this is another way of saying the previous point.

The absurdity of this whole position is easily perceived….

But that’s another post.