Archive for July, 2009

Infinity vs. Infinity

Monday, July 13th, 2009

In Chapter 2 of Book I of the Physics, Aristotle says that if being is One in the sense of being only substance, then it can’t be infinite, for to be infinite is in the category of quantity, and quantity is an accident that subsists in a substance.

This leads me to a couple of questions.

First, I understand that accidents subsist in a substance.  Now, suppose you’ve got a thing whose nature it is to be infinite.  It’s part of the thing’s essence, its species.  Is this infinity still an accident?

Second, God is One, and perfectly simple; if I understand it correctly, God has no accidents.  Yet God is said to be infinite.  I would gather, then, that this is an analogical use of the word "infinite".  The infinite of quantity and the infinite of God are distinct, but related analogically.  Not so?

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.

The Principles Giveth and the Principles Taketh Away

Sunday, July 12th, 2009

In Chapter 1 of Book I of the Physics, Aristotle touches on the nature of a science, by which he means a body of knowledge.  A science is anything about which you can have certain knowledge as opposed to mere opinion.  Both philosophy and geometry are sciences in Aristotle’s sense.

But the point he makes, or rather makes use of, is this.  Every science has certain principles on which it is founded.  By its nature it takes these principles as given.  For example, geometry assumes certain definitions and axioms; physics presumes multiple beings in motion.

A science is responsible only for those conclusions that can be drawn from its principles.  Indeed, it is only competent to judge propositions that purport to be drawn from its principles.  Other propositions are outside of its field of view, and it cannot address them.

Among these propositions is the one that says, "This principle, upon which you base your science, is wrong."  No science is competent to pass judgment on the principles upon which it is based.  This is not to say that this is a question of no importance to the practitioners of the science in question; clearly, it’s crucial.  But it cannot be addressed in terms of the science itself.  It must be addressed on some higher, prior basis.

And this is why, of course, that experimental science as it is practiced today is not competent to address questions such as the existence of God, or the nature of human consciousness, neither of which are explainable in terms of controlled experiments involving the movement of atoms. 

As a blog post I read recently pointed out, modern experimental psychology and neuro-biology takes great pains to eliminate the effects of rational human choice from its experiments.  Such experiments are testing Man not as Rational, but as Animal, and naturally they miss the mark here too.

Physics, or Natural Blogging

Sunday, July 12th, 2009

You can’t study Aquinas for long without realizing the need to come to grips with Aristotle.  James Chastek over at Just Thomism recommends starting with Aristotle’s Physics; and more particularly with Glen Coughlin’s translation, Physics, or Natural Hearing.  The introduction to Prof. Coughlin’s translation has this to say:

…it is not reasonable to begin one’s study with commentaries; we should first read the text and then turn to the commentators when our own powers of comprehension fail.  This will not take long.

Nor did it.  I’ve been wrestling with Prof. Coughlin’s translation on and off for some months, and gotten some notions, but I’ve not gotten far.  Prof. Coughlin goes on to say that the best commentary on the Physics is that of St. Thomas Aquinas, and particularly recommends this edition, published by Dumb Ox Books.  I’ve since received this, and I’m liking it a lot.

The book includes the complete text of the Physics, in comfortably sized sections interleaved with Thomas’ commentary.  Thomas doesn’t settle for merely explicating the text; he puts the passage in context, and also gives considerable background that Aristotle assumes.  And since Aristotle’s own words are separate, it’s possible to give them a good study before moving on to what Thomas has to say about them.  Good stuff.

I don’t intend to blog my way through Aristotle the way I’m doing through the Compendium Theologiae, though I’ll undoubtedly have a few reflections to make as I go along.

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.