Secretum secretorum - De Mirabilibus Mundi - Human condition - Mind
Background for Ars Magica sagas

Aristotelian Epistemology and Its Arabic Developments

Around the late-twelfth and early-thirteenth centuries, the works of Aristotle and the Arabs began to appear in the West in Latin translations. And with them came a whole new outlook. For the first time, the Latin West was exposed to a technical philosophy. (There were some beginnings of this sort of thing around the time of Abelard, independent of the new translations, but what we are talking about now was something of an altogether different order of magnitude.) For the first time, we get a serious theoretical challenge to what had become the standard Augustinian way of looking at things (tempered here and there with a dose of Pseudo-Dionysus). At the same time, the universities began to emerge from the old educational institutions. Henceforth in the Middle Ages, philosophy would be an increasingly academic affair, in a way it was not for Augustine or even for Anselm and Abelard.

It cannot be emphasized too much how great a shock the recovery of Aristotle was to the Middle Ages. The Augustinian tradition basically had a very low opinion of the powers of the unaided human intellect. It was incapable, by itself, of attaining any knowledge at all worthy of the name. It needed some assistance from outside - by illumination. This notion was common doctrine by the twelfth century. As seen in the theory of illumination of Augustine, it was hard in practice to explain just how illumination differed from revelation. This was seen as long ago as Justin Martyr, with his view that everything true in Plato was stolen from Moses. Put in not quite so crude a form, the standard view was that no knowledge worthy of the name could be had without faith. Even Anselm, who thought he could find necessary reasons for the truths of the faith, said "Unless I believe, I will not understand".

Into this context came Aristotle, a pagan, who did not have faith. He presented a doctrine in which the human mind was thought of as having much more power in its own right. He had a very high opinion of the unaided intellect. So here for the first time we have a theoretical challenge to the accepted view. And the details of that challenge had been fairly well worked out in Aristotle himself.

But more. Not only did Aristotle present a theory that challenged the accepted one, he also seemed himself to be living proof (well, actually he was dead, but you get the idea) of that theory. In other words, he seemed to have been able, without the aid of faith, and solely on the basis of his unaided intellect, to arrive at some pretty important truths well worthy of the name.

You don't get this problem with Plato in the Middle Ages. You might have thought that people would be worried about the fact that, while Plato's view is more congenial to them, nevertheless Plato thought it up without the aid of faith - he was a pagan too, after all - and how is that possible? The reason you don't get this problem is that the Middle Ages had almost nothing of Plato's own writings. Platonism was everywhere, as Gilson says, but Plato was not to be found (with the small exception of the first half or so of the Timaeus). The Platonism that was in circulation was already thoroughly mixed with the Church Fathers, with Augustine - in short, with Christian doctrine. It had, so to speak, been "baptized". There was nothing scandalous about it. With Aristotle, on the other hand, you get a whole new batch of texts from his own hand, as it were, and this puts the issue into much sharper focus.

Thus we have in the late-twelfth and early-thirteenth centuries a crisis of sorts in mediaeval thought. Here is this upstart Aristotle, whose doctrine calls into question the old and venerable views that were commonly held (and remember, there were good reasons for holding them - recall the problems the doctrine of illumination was designed to solve). Furthermore, he seemed to be able to support his doctrine, both with his own example and by rigorous arguments. What are you going to do about it?

This problem was especially aggravated, because some of Aristotle's positions were outright heresy. Among the most blatant were: (a) the eternity of the world; (b) the claim that the separated substances (which could only be interpreted as God and the angels - what else could they be?) have no concern for the world and in fact don't even know about it; (c) the dubious state of the soul in Aristotle (is it immortal or not?). Some people - for example, Bonaventure in the thirteenth century - said that all this just went to show that unaided reason wasn't enough to reach the truth. Look what happens!

Aristotle's Theory

It is this last point that I want to address, by looking at how the Aristotelian theory developed at the hands of Aristotle's successors in the late classical and in the Arab world, up to the time it reappeared in the Latin West along with the Arabic commentaries.

Let's go back and look at Aristotle himself on how the soul knows. The basic passages are from De anima, Books II and III, especially Book III, Chs. 4-5. An excellent and very clear account of the development of the tradition may be found in David Knowles, The Evolution of Mediaeval Thought, Ch. 17, part 1.

The basic theme of Aristotle's epistemology is this: Understanding is to be thought of after an analogy with sensation. Intellection is like sensation. This is crucial to understanding Aristotle on these matters.

Well, what then happens in sensation? Look at passage (1) in Text \s2. An external, physical individual acts on the sense organ, for instance, on the eye. The organ is an organ of a sense faculty or power of the soul. The object acts on the organ and leaves in the faculty (which uses the organ as a tool - 'organon' = `tool' in Greek) an impression.

The object acts on the organ, which is part of the body, and as a result leaves an impression on the sense faculty, which is part of the soul. This is already totally non-Augustinian. For Augustine, recall, bodies cannot act on the soul at all.

Aristotle explicitly uses the signet-ring analogy here. This is an analogy that gets used a lot to illustrate all kinds of doctrines.

Now what is this impression? In the Latin Middle Ages it was called a species, or a sensible species. This is not to be confused with `species' as opposed to genus. From the sense of the word `species' we are talking about now, we get the English word `specious', meaning "apparent", and referring to the appearance of the thing. (Actually, the word `species' as opposed to genus is also derived from this more basic sense. But don't let that confuse you.)

Basically, this species or impression on the sense faculty is everything involved in the individual - essentially or accidentally - except for the matter. The matter is "left behind". Consider the seal-ring analogy again. The ring implants an exact duplicate of the formal structure of itself on the wax, but it does not leave its matter there, the gold or the bronze, for example. If the ring is round, the impression is round. If the ring has serrated edges, the impression has serrated edges. But even though the ring is gold or bronze, the impression is still just wax.

The sensible species is just as individual as the original object was. Although matter - so called prime matter (that is, completely indeterminate stuff - it is a topic of some dispute whether Aristotle himself had anything like prime matter in his doctrine. In my own view, he certainly should have had it if he didn't, and in any event his doctrine was frequently interpreted in terms of prime matter, which is enough for us.) - is left behind, the image that remains, the sensible species or impression, keeps all the detail of the original. It is an exact duplicate of the individual object that caused it, and of no other.

(Technical note: There is a sense in which accidents individuate on this view. But this is not the same sense as in Boethius' strongly realist view, or in William of Champeaux's first view. In those theories there was no real role for matter - that is, real matter, not "matter" in the analogical sense of a "material essence".)

Abelard, said that the object of thought, whether individual or universal, had a different kind of existence than the real objects did. I said that later on that kind of existence or reality would come to be called esse intentionale as opposed to esse reale. Well, the same thing seems to be going on here, as early as Aristotle.

Every essential or accidental form that exists really in the object, exists mentally, intentionally, in the sensible species or impression in the sense faculty. Just as, in the real world, all these essential and accidental forms are grounded in, inhere in, prime matter, so too in the intentional world of sense impressions, they all inhere in the sense faculty, which therefore acts like prime matter. It is not prime matter, of course, but it plays a similar role. The sense faculty then is a kind of mental analogue of prime matter.

In this way, then, the sense faculty becomes formally its object. That is, it takes on the formal features of its object. Not just similar features, but identically the same features. What exists in the mental mode in the sense faculty is not just something more or less similar to the object that caused it. It is exactly that object, just as individual and detailed as the external object. If it were not, then it would not be a representation of that object, but of another one more or less similar to it.

This is not to say, of course, that when I look out and see a tree, there is a tree growing in my visual faculty. Of course not. The difference is one of the manner of being. In the external object, all these detailed formal features exist really in prime matter. In sensation, identically the same forms exist mentally or intentionally in the sense faculty.

This approach grounds the objectivity of sensation. This is not a "representational" theory in the sense that any inference is required to get you from your impression to the external object. The species in the sense faculty just is the external object - "formally" speaking, of course.

Augustine stated that, in the case of any real and certain knowledge, the object must be present in person and not by proxy. Aristotle is in effect saying the same thing here about sensation, although he confines it to the formal features of the object. You don't have to infer from the fact that your sense power is actualized in a certain way to the fact that some external object is acting on it.

This is just an application of the general Aristotelian claim that the cause's causing is identical with the effect's being caused. It is the same process. The fire's heating the water is the very same process as the water's being heated by the fire. So too, the sense power's being actualized by some external object is identically the same process as that external object's actualizing the sense power. No inference is involved, and therefore all the traditional "representational" problems of, say, Cartesianism, are neatly sidestepped.

Now let us extract some features from the theory as it has been developed so far.

(1) The sense faculty is totally passive to begin with. It is potentially its objects - always "formally speaking", of course.

(2) Then it takes on the sensible species, and is "reduced, as they say, from potentiality to act. Before, it was potentially the object; now it is actually so, just as the sealing-wax to begin with is potentially the fully formed seal, and when it takes on the impression it becomes actually so.

(3) Here is a general Aristotelian principle: Whenever you have something reduced from potentiality to actuality (that is, whenever you have some actualizing process going on), you need a cause. In the case of sensation, it is the external object that acts on the sense organ. That is the cause.

Remember the guiding thread that I introduced above: Intellection is like sensation. Therefore, analogously, a similar thing must happen in intellectual cognition, in the formation of concepts.

Of course, intellection is not sensation; it is only like sensation. What is the difference? Here we get an important slogan that people threw around in the Middle Ages: Sensation is of particulars, but understanding of universals ("Sensus est particularium, intellectus autem universalium.") Commit that to memory. It will be very important.

Just as the sense faculty takes on the formal features of the external object - both the essential and the accidental ones - stripped of prime matter, so too the intellect takes on, receives, the universal form of the same object, and becomes formally identical with its object. Identical with its object, note, but not identical with all its object. It takes on the universal form, but not all the accidental forms that serve to distinguish this individual object from that one. I leave it as homework to the reader to figure out just what kind of identity relation this is. It is certainly not the kind of "identity" that is talked about in first-order logic nowadays. But it is not nonsense.

Just as this notion grounded the objectivity of sensation, so too it grounds the objectivity of intellection. There is no basis for skepticism here.

Just as the product of this taking on of forms was called, at the level of sensation, a sensible species, so too at the level of concept-formation it is called the intelligible species. How then does the intelligible species differ from the sensible species?

Just as the sensible species left behind prime matter, but not the peculiar and identifying accidents, here the intelligible species leaves behind the peculiar and identifying accidents and ends up with only the universal or essence.

Given this framework, there is an argument that comes in here for the separability of mind from body.

Consider sensation - for example, vision. As a faculty, it is supposed to be like prime matter, capable of taking on all (visible) forms. Like prime matter, therefore, it cannot then itself, by nature, have any of those (visible) forms. If it did, it would no longer be potential and indeterminate like prime matter, but rather determinate and already reduced to act - and so incapable of doing its job. Hence, the visual faculty does not by itself have any visible form. In short, it is invisible. And similarly for the other senses.

Now the intellect, likewise, is capable of knowing all physical objects, capable of taking on their forms. (For the purposes of this argument, it does not matter whether the intellect is also capable of knowing immaterial objects.) Thus it acts like prime matter in a way, just as the visual faculty did. And like prime matter, it cannot by nature have any of these forms that it is able to take on. Conclusion: The intellective faculty, or mind, does not by nature have any corporeal form. It simply doesn't need any, and in fact could not do its job if it had one. That is why Aristotle says it is not "mixed with the body".

What we have here is an argument for the separability of the intellective faculty. It doesn't need a physical body, which is where you find corporeal forms. And since it doesn't need a physical body, it can survive death - that is, the separation of the soul from the body.

There are three problems with this argument - at least problems of interpretation, if not outright problems with the doctrine itself:

(1) Does the argument contain a quantifier mistake? That is, does it argue like this: Since for all corporeal forms F, the intellective power can do without F, therefore, it can do without all corporeal forms whatever? (Similarly, I can do without any particular kind of food, since I can substitute another kind to get all my "essential nutrients". But it does not follow that I can do without all foods whatever.)

(2) Does it confuse the intentional with the real? To say that the intellective faculty does not need to be intentionally what any physical object is really is not automatically to say that the intellective faculty need not be really what some physical object is really - that is, that it need not really be a physical object. Or is it? In other words, if the mind were really a physical object, "mixed with the body", as Aristotle puts it, and so had a corporeal form of its own, would it follow that it also had that form in the intentional sense of "having a form"? Some such assumption seems to be required if Aristotle's argument is going to work.

(3) Would not exactly the same kind of argument show that prime matter likewise "is not mixed with the body", and that therefore prime matter too is separable from, could exist apart from, any physical object? But that of course would be definitely non-Aristotelian. If Aristotle held a theory of prime matter at all, he certainly did not think it could exist separately, on its own, apart from physical bodies. Prime matter is a distinct metaphysical ingredient, but it only exists in combination with a corporeal substantial form.

Let us just set these problems aside. Perhaps they are really more problems of interpretation than they are real sore points in the theory itself. (Perhaps they aren't.) Instead, I want to turn to two other questions that can be asked of this theory:

(1) If sensation is of particulars or individuals, but understanding is of universals, how is it possible to have any intellectual knowledge of singular things, of individuals? This is an important sticking-point for Aristotelian epistemology. In part it was difficulties over just this question that led to the abandonment of Aristotelian epistemology in the fourteenth century.

(2) How is the intellect reduced from potency to act? What causes the indeterminate matter-like intellect to become to some extent determinate, to take on a form? What is the agent cause here? (Remember from above, we always need an agent whenever we have something reduced from potentiality to actuality.)

In sensation, the agent cause was the physical, external object, which acted on the senses. Recall the signet-ring metaphor again.

The point of the ring metaphor is that each impression leaves the same individualized form in different substrates. So we can't just say that it is the same physical object, which acts like the ring and leaves an impression on the sense faculty, that also acts like a ring and leaves an impression in the same way on the intellect. For then the intelligible species would be just as individualized as the sensible species, and there would be no distinction between sensation and intellection.

Hence we need a different agent cause in the case of intellection. Something has to be done to the object's individualized form - the accidents have to be stripped off - to make it ready to be impressed on the intellect.

Now it turns out the there are really two functions to the intellect. The intellect, or that function or part of the intellect, which is passive and receptive is called the "possible" intellect or "material" intellect by various later people. But the job of preparing the form to be imposed on this possible or material intellect is performed by something else, something called the "agent" intellect. And this is a new ingredient.

The idea is that individual forms, the things that get impressed on the sense faculty, are only potentially intelligible, just as colors are only potentially visible until light shines on them. The agent intellect then is the "Light of the Mind". This terminology goes back to Plato's Allegory of the Cave, and his metaphor of the sun, in the Republic, and it sounds a bit like Augustinian illumination. It is quite a different theory, of course, despite the terminological similarities. Nevertheless, keep an eye on these terminological resemblances.

On the other hand, material objects are actually sensible, and therefore there is no need for a separate agent sense to reduce the passive sense-faculty from potentiality to act. The object itself can do that. (The external object may be said to be only "potentially sensible" insofar as, for example, a visible object needs to have light cast on it before it can be actually seen. But the point still stands. We don't need to introduce a new side to the sense faculty itself, an agent sense. I should mention here that some later authors in the Middle Ages did in fact speculate about whether this was correct, about whether an agent sense was needed just as much as an agent intellect was.)

Later on in the same passage, Aristotle says that it is mind (nous) in this sense - that is, the agent intellect - that is separable and unmixed, and it alone. Passive mind, he says, is corruptible. It dies with the body.

But now we have a problem. What about the argument Aristotle just gave us in the previous chapter (De anima, III, 4, rather than III, 5), that mind, by which he there meant passive mind, was unmixed and separable?

On the basis of this apparent conflict in the Aristotelian texts, there were two problems inherited by his successors:

(1) Is only the agent intellect, or are both the agent and passive intellect, separable? This was the problem of immortality, or part of it. Just what is it that survives death?

(2) Is the agent intellect in the soul, even though it is separable? Or is it something outside the soul, and for that matter something one and the same for all people, just as (to use Aristotle's own metaphor) the light of the sun, which reduces potentially visible objects to actually visible ones, is the one and the same for everyone? (You begin to see at least one reason why some people might think that the cases of the agent intellect and an "agent sense" are not all that different.) This is the problem of personal immortality, or part of it. If the only part of my soul that is immortal is one and the same for everyone - or worse, if it was never really in my soul at all, but is rather some odd external thing - then I can hardly speak of my own personal immortality.

Precisely because Aristotle had so little to say in the end about all this, it became a focal point for a long and involved tradition of interpretation. Let's look at that tradition.

Let us look first at Themistius, an important fourth-century Greek commentator on Aristotle. Themistius has three kinds of intellects. Or more precisely, he has three terms for what are really two different kinds of things. Themistius distinguishes the active or agent intellect from the material or possible intellect. These correspond to Aristotle's active and passive.


Let us look first at Themistius, an important fourth-century Greek commentator on Aristotle. Themistius has three kinds of intellects. Or more precisely, he has three terms for what are really two different kinds of things.

Themistius distinguishes the active or agent intellect from the material or possible intellect. These correspond to Aristotle's active and passive intellects. He answered question (2) - just before the above table - by saying that both are in the soul, and that each person has one of each, his own one of each. That is, for Themistius, nous, the mind is a part of the soul. And furthermore, we each have our own mind. We don't share one. This holds for agent mind as well as for material or possible (Aristotle's passive) mind. Themistius also answered question (1) - just before the table - by saying that both are separable. This is going to be essentially Aquinas' position in the thirteenth century. Note that it violates Aristotle's explicit statement that passive mind is corruptible.

Themistius also talks about something called the "speculative" intellect. This is not a third entity. The "speculative" intellect is just what the possible intellect is called after it has been acted on by the active or agent intellect. It is what you end up with after the whole business is completed and we actually have a concept successfully formed and in our thought. (Similarly, for Augustine a "man" was not a different entity from a soul. Rather it is just that the soul is called a "man" when it satisfies certain conditions.)

Alexander of Aphrodisias

Now let us look at Alexander of Aphrodisias, a major Greek commentator on Aristotle from around 200 A.D. He was earlier than Themistius, but I wanted to treat Themistius separately, since Alexander's doctrine begins the more influential tradition. His commentary on the De anima was strongly influenced by Platonic and neo-Platonic considerations, so that what you end up with is hardly pure Aristotle.

The main features of Alexander's position are these:

(1) The soul is the form of the body, and therefore is corruptible, like all forms of corporeal objects.

(2) There is a passive intellectual faculty in the soul, called the material intellect (this was also Themistius' term for it), and there is a distinct one of these for each person. This much is like Themistius. But, unlike Themistius' doctrine, Alexander's has it that the material intellect dies with the body, since it is part of the corruptible soul.

(3) There is also an agent intellect outside the soul, which activates the material intellect, reduces it from potentiality to act. It acts like the light of the sun. This is not at all like Themistius' version of the agent intellect, which was in the soul.

(4) The action of the agent intellect on the material intellect results in the "acquired intellect" (intellectus adeptus). This is the same notion as Themistius' speculative intellect; only the term is different. Is it immortal? Probably not.

(5) There is only one agent intellect. It services all people. Furthermore, and this is something new, theagent intellect is identical with God.

It is interesting to go back and compare this doctrine with the Aristotelian texts, to see how the theory fits them, and also to see what Alexander has to add to get a coherent picture.

This kind of theory prevailed in later Greek philosophical circles, and influenced Augustine. It was more or less "in the air" in intellectual circles in Augustine's day, even though he himself certainly never read any Alexander. (His Greek was terrible, as he himself admits.)

Notice some of the main features of this doctrine:

First, there is no personal immortality. There is nothing unique to a given individual human being that survives his death. Augustine of course won't be able to buy that.

But there is also the theme that the intellectual powers that belong to a person as his own are quite incapable of arriving at any knowledge by themselves. They need help from outside. The human mind needs to be illumined by the agent intellect, which is God. Recall Aristotle's own "light" metaphor. Alexander is here interpreting Aristotle's words in a way that sounds very Platonic. (Remember the allegory of the cave.)

This of course should sound suspiciously like the doctrine of illumination, found in Augustine. Let us pause to look at this a bit.

Recall one of the differences between Plato's theory of reminiscence and Augustine's theory of illumination. For Plato - or at least for a strong element in Platonism - human souls were lesser gods. And so when they came in contact with the Forms, which were eternal and immutable and so had the characteristics of divinity, they could under their own power acquire knowledge of those Forms by acquaintance. There was no unbridgeable difference of rank or station. In Augustine, however, there was a clear gap between creator and created mind. The latter could never under its own power acquire knowledge.

Alexander's position fits more closely with Augustine's than with Plato's on this point. There is an important difference between God and everything else. God is the agent intellect, and the only one there is. Every other intellect requires the action of the agent intellect in order to know. It cannot know under its own power. And that inability is not just a matter of degree, but a matter of kind. Augustine, of course, did not pick up the Aristotelian technicalities and terminology. But the basic idea remains. The unbridgeable gap between creator and created intellect on his view mirrors the unbridgeable gap between the agent and the material intellects for Alexander. The latter can never do the job of the former all by itself.

In this connection, it is curious that Aristotle, who on the whole has a very strong opinion of the unaided human intellect, should have been interpreted in a way that makes it impossible for the unaided intellect to have any knowledge at all.

Alexander's interpretation was not only indirectly influential on Augustine and his Latin successors. It was also influential on the Arabs. That is why you get something very like an Augustinian doctrine of illumination in Arabic philosophy; they had a common source. It is also why when, in the thirteenth century, the Arabs began to be widely read by the Latins, the Latin Augustinians could so readily absorb what they read. Gilson has coined the term "Avicennizing Augustinism" for this. But before we get to Avicenna, there is a preliminary episode in our story, namely, Alfarabi (870-950).


Alfarabi lived shortly after Eriugena. He enriches and embellishes Alexander's doctrine, but basically stays in the same line of interpretation. Whereas Themistius and Alexander had three intellects (or at least three terms - the third intellect is just the result of the interaction of the other two), Alfarabi has no fewer than four intellects. They are:

(a) The potential intellect. This is Alexander's "material" intellect, Themistius' "material" or "possible" intellect, and Aristotle's "passive" intellect. It is like matter. Alfarabi uses Aristotle's analogy of the wax (see Hyman and Walsh, p. 215). The potential intellect is in the soul, and there is a different one for each person.

In discussing the potential intellect, Alfarabi seems to introduce a distinction we haven't seen yet. There are two senses in which the potential intellect for Alfarabi can be said to be potential: (i) in an absolute sense - that is, when it has no forms impressed on it yet at all; (ii) in a relative sense - after it has a form impressed on it, it still remains potential with respect to other forms. This does not by itself entail, but it nevertheless suggests something I think Alfarabi in any case accepts, namely that the potential intellect can take on several forms simultaneously. He talks about this kind of thing when he is working up to the third kind of intellect, which I'll discuss in a moment. See Hyman and Walsh, p. 216. (It does not entail this, any more than the fact that a lump of clay that in fact has a certain shape is nevertheless still potential with respect to other shapes entails that the lump of clay can have two shapes at once. It is potential with respect to those other shapes in the sense that it can take them on, but only by losing the shape it now has.)

Notice, incidentally, how the doctrine that the potential intellect, which is like prime matter, can take on a plurality of forms at once, is just the epistemological correlative to the metaphysical doctrine of the plurality of forms. That metaphysical account was a characteristically Platonic/neo-Platonic one.

Notice also that if the potential intellect can take on several forms simultaneously, then the argument for the separability of that intellect, why it cannot be "mixed with the body", loses much of its efficacy. We shall see below what Alfarabi has to say about immortality.

(b) When the potential intellect takes on a form (or several forms), it becomes the actual intellect. This is Alexander's "acquired" intellect, or Themistius' "speculative" intellect. It is not the agent intellect.

(c) Alexander also has something he calls the "acquired" intellect (Hyman and Walsh, pp. 216-217). Although we have seen this term in Alexander, Alfarabi's notion is one we haven't seen yet. It's pretty strange, so hang on. Let's start by considering the kinds of things that actually exist in the world.

(i) There are, first of all, material objects. They can be understood insofar as they have in them individual forms, which, until they are made intelligible by abstraction (the agent intellect), are only potentially intelligible.

(ii) So we understand material objects by abstracting their forms. Such a form then becomes an intelligible, not just in potency, but in act - that is, it becomes actually intelligible. Hence it is now one of the "actually" existing things of the world, and so I can understand it too by a kind of reflex act.

In short, first I understand the form insofar as it comes from matter. Then, I understand it insofar as it is intelligible in act.

Now the intelligible form in act, that is, as actually understood, is formally identical with the intellect itself - the actual intellect, in Alfarabi's sense of the term. (This is just good old Aristotelianism. The knower is the known.) Thus when the intellect understands the forms in the second of the two ways just distinguished, it in fact understands itself. See Hyman and Walsh, p. 216.

When it does this, it becomes what Alfarabi calls the "acquired intellect". But this is not the "acquired intellect" in Alexander's sense of the term. Alfarabi seems to say that this comes about only after the intellect gets all the forms in actuality. That is, the acquired intellect for Alfarabi is the intellect that has reached a complete and thorough understanding of the material world.

All of this sounds pretty strange, to be sure. Nevertheless, you may be surprised to learn, it does have an authentically Aristotelian text to back it up. Whatever that text meant to Aristotle, this is what happened to it at Alfarabi's hands. Alfarabi wasn't just making it up out of whole cloth.

It is the acquired intellect, in this sense, that for Alfarabi is immortal. With the acquired intellect, we begin to understand things insofar as they are separated from matter. This is the lowest degree of such understanding of immaterial things. As we shall see, there is a kind of neo-Platonic hierarchy here.

(d) Finally, there is the agent intellect. This is separated from matter, as it is for Alexander. And, again in agreement with Alexander, it is one and the same for all people. But, in contrast with Alexander's doctrine, for Alfarabi the agent intellect is not God.

Here is where the neo-Platonism that gets mixed up into later Aristotelianism becomes quite plain. The neo-Platonic One is identified with Allah or God. It contemplates itself and produces an intellect, which is the first emanation. This intellect is the First Intelligence, which acts as a final cause of the motion of the outermost, all-encompassing celestial sphere.

This First Intelligence in turn produces a Second Intelligence, which moves (as final cause) the sphere of the fixed stars. And so on. Just exactly how many stages there are in this process is an astronomical question, but here is the basic idea. The First Intelligence is the final cause of the motion of the outermost sphere. The Second Intelligence is the final cause of the motion of the sphere of the fixed stars. In the same way, we have a Third Intelligence going with the sphere of Saturn, a Fourth with the sphere of Jupiter, a Fifth with the sphere of Mars, a Sixth with the sphere of the Sun, a Seventh with Venus, an Eighth with Mercury, a Ninth with the moon, and the Tenth and last Intelligence, which is the final cause of motion down here in the so called sublunary world.

The sublunary world is the world below the moon in the astronomy of the time. In other words, it is our world, down here on earth. It is the world of generation and corruption. The celestial spheres are subject to local motion, but not to generation or corruption. The Tenth Intelligence is the final cause of the generation and corruption in this sublunary realm. It is the cause of the succession of forms that come and go here. Hence, Avicenna later on would call it the "Dator Formarum" - the "Giver of Forms". (Actually, he called it something in Arabic, which was then translated as "Dator Formarum".)

Now why do we need all these stages? Well, there is of course a general neo-Platonic difficulty with seeing how to get plurality out of unity. Lots of people felt that there was something conceptually wrong with doing this in one step. You cannot do it directly. Plurality has to be far removed from the direct activity of the One. Of course, Judaeo-Christian doctrine will have none of this. God acts directly on his creation. There is no need for these intermediary intelligences - at least not for this kind of job.

The details of all this are obscure, and need not detain us. But there is one other very important point to notice. This Tenth Intelligence, which Avicenna will later on call the "Dator Formarum", is also the agent intellect for Alfarabi. In short, the Tenth Intelligence not only puts forms into matter, it also puts them into minds, into potential intellects. What it does on the physical level with generation and corruption it does also on the epistemological level too.

Here are two things to notice about Alfarabi's theory:

(1) There is one agent intellect for all people. It is the Dator Formarum or the Tenth Intelligence. It is not God.

(2) Alfarabi's view allows personal immortality in a rather unusual form, via the acquired intellect. But notice that the theory does not guarantee personal immortality. If you don't spend your life getting all those forms into your intellect, you won't make it.


After Alfarabi we come to Avicenna (980-1037).

Avicenna was arguably the greatest of all the Arab philosophers, and for that matter one of the greatest philosophers of all time. In his interpretation of Aristotelian psychology, however, he depended almost entirely on Alfarabi. Basically, his schema is the same as Alfarabi's, with the following changes:

(1) Alfarabi's potential intellect is called the "material" intellect, following the earlier terminology of Alexander and Themistius.

(2) Alfarabi's actual intellect is called the intellect in effectu. I'm not sure whether this is really a difference or not - even a terminological one, since I've not yet seen the Latin text of Alfarabi on this point. This peculiar use of the phrase 'in effectu' to mean "actual" or "in act", as opposed to "in potency", is a characteristic Arabism. When you see it in Latin texts, you know that some Arabic influence is operating behind the scenes.

(3) Avicenna has nothing like Alfarabi's acquired intellect.

(4) He does, however, have an intellect in habitu. That is to account for "habitual knowledge", knowledge in the sense in which I can be said to know Latin even when I am asleep and not actually exercising that knowledge. Alfarabi has nothing like this. Aristotle of course has the notion of habitual knowledge, but he doesn't reserve a special kind of intellect for it. I am not sure how Avicenna relates this intellect to the others.

(5) Avicenna also has something called the "given" intellect (intellectus accommodatus), which is the material intellect as receiving the form. Again, I am not clear how this differs from the intellect in effectu except perhaps insofar as a process differs from its result.

Let us now look at some problems with this "Alfarabic-Avicennian" theory:

(a) On this view, how is it that we have to work to acquire knowledge? Why not just sit back and wait on the agent intellect to do its job? Recall that we had exactly the same problem with Augustinian illumination.

Alfarabi tries to answer this (Hyman and Walsh, p. 220). He says that the matter (that is, the potential intellect) must be "prepared" and "impediments" must be removed. He's right, of course. We do have to work hard to prepare our minds to know. But this is not much of an explanation of that need. Avicenna also talks like this.

(b) The agent intellect does not act on impressed forms received from external physical objects in sensation (the sensible species). It does not do something to them (to wit, make them abstract and universal) and then impress the result on the potential intellect. In other words, the form the agent intellect impresses on the potential intellect is not one it originally got (before "doing something" to it) from the activity of the external, physical object. Rather, it takes it from its own store. That is why is a "Dator Formarum".

In short, the whole tone of this view has changed. We started off with Aristotle, for whom all our knowledge comes ultimately from the senses, and for whom the agent intellect operates on the sensible species acquired from external objects, makes them abstract and then impresses them on the passive intellect. Now the whole thing is turned around. No intellectual knowledge comes from the senses. It is all implanted by the agent intellect, which got it from its own store of forms. The agent intellect did not have its own store of forms for Aristotle. It was not a warehouse but a processing plant. The whole job of the agent intellect has been radically altered.

What has happened is that Aristotelian texts and Aristotelian terminology have been used to come up with a doctrine that is a virtual duplicate, in more technical terminology, of Augustinian illumination. The only thing that's been added is the hierarchy of intermediary emanations.


Finally, let us look at Averroes (1126-1198). Averroes (pronounced Uh-VAIR-oh-ease) lived in Moorish - that is, Islamic - Spain, at least for part of his life, whereas Avicenna and the others lived in the Eastern part of Islam.

Averroes was the last of the great Islamic philosophers in the Middle Ages. And, unlike his predecessors, he was a strict Aristotelian, or at least he wanted to be. He wanted to purify Aristotle from the Platonic and neo-Platonic elements that had come to be associated with it.

Averroes wrote a number of commentaries on Aristotle. These commentaries became so well known in the Latin West that Averroes was referred to simply as "the Commentator".

Averroes thought things had got out of hand. Aristotle's psychology had got just totally turned around by Avicenna and his predecessors.

Averroes argues that, since Aristotle in some places says that the passive intellect is separable from the body and capable of surviving death, and in other passages seems to deny this, obviously he must have had distinct things in mind!

For Averroes, there is indeed an agent intellect and a passive intellect, which he calls the material or possible intellect (using Themistius' terms). They are distinct from one another, as Aristotle had argued. But neither of them is in the soul as one of its faculties. The soul is the form of the body, and like all bodily forms, is destroyed when the body of which it is the form is destroyed. Thus, the soul is not immortal - as a whole, or in any part. The agent and material or possible intellects, therefore, since they survive the death of the body, were never forms of the body or parts of that form. They are separated all along.

Furthermore, Averroes thinks that the agent intellect and the material or possible intellect are both one for all men. It is not that I have my own separated agent and material intellects, and you have yours. We have both have the same agent intellect, and we both have the same material or possible intellect, which is distinct from the agent intellect. I do not know his argument for this.

Furthermore, when Aristotle talks about a passive intellect that is part of the soul and corruptible with the body, he is not talking about the agent or material (possible) intellect. Instead, he is talking about the imagination, the faculty of storing up and presenting sensible species or phantasms. (Imagination here is not just the fancy - it is a combination of that and sensory memory.) This faculty is intimately tied up with sensation. I can imagine in the visual mode - that is, I can picture to myself things I have seen or things I have made up. Similarly, I can imagine aurally, run through a tune in my head. And, since it is so intimately tied up with sensation, and so with the physical organs of sensation, the faculty of imagination dies or is destroyed when those organs die.

Hence, we have a new intellect with Averroes. He calls it the "passive intellect". It is identical with imagination. It is the only thing in the entire psychological apparatus that is personal and private. I have my imagination or passive intellect and you have yours - they are distinct. Just as our bodies are distinct, so too our passive intellects. But the passive intellect is also corruptible. Therefore, there is no personal immortality for Averroes. The only thing personal here is not immortal.

What is the connection between the separated agent and material intellects and the individual knower? Aristotle had held that human knowledge always requires the presence of a sense image, a phantasm or sensible species. (See De anima III, 7, 431a14-17.) For Aristotle, knowledge is derived from these sensible species.

This is so not only for our originally acquiring a concept, but also whenever we use a concept already acquired. There is always some sense image or other that accompanies our thoughts, and from which we read off the abstract concept. Just as geometers use figures, so too here. This is so even when we are dealing with things of which no sensible representation will be adequate or accurate - for instance, the separated substances or geometrically perfect circles.

Now Averroes thinks that the agent and material intellects, which are separated, come into contact with the soul only through the phantasms (images). He realizes the radically non-Aristotelian element in Avicenna's claim that the agent intellect has its own store of concepts. He rejects that view entirely.

For Averroes, the agent intellect has no forms of its own. It takes as its materials, not any forms from its own store, but the phantasms. It acts on them, abstracting the universal concept and implanting it in the separated possible intellect.

The materials worked on here are private and personal. They are my own personal sense images (sensible species). The processing plant, however, and the material intellect, where the results are ultimately sent, are common and public, and separated from me. The only connection with me is this very tenuous one: they are my sense images that are being worked on.

The weak spot in this theory is of course the exact nature of the connection between the separated intellects and the imagination. Averroes never works this out very well, and some Latin authors, especially Aquinas, will hit him hard on this very point.

Secretum secretorum index - De Mirabilibus Mundi index

Atlas Games - publishers of Ars Magica          Redcap - Ars Magica portal

Last modified: Sun Dec 27, 1998 / Jeremiah Genest