Averroes on Psychology and the Principles of Metaphysics

Richard C Taylor. Journal of the History of Philosophy. Volume 36, Issue 4. October 1998.

First translated from Arabic into Latin in the early thirteenth century, the philosophical works of Averroes were initially respected as valuable aids to understanding the true philosophy of Aristotle. William of Auvergne, Bishop of Paris and author of a philosophically astute theological synthesis of Greek and Arabic thought with Christian doctrine, openly expressed his appreciation with praise for Averroes. But by the mid-thirteenth century many of Averroes’ teachings were under attack with his conceptions of human nature and separate immaterial intellect the subject of sharply focussed and heated argumentative assaults by Aquinas, Albert and others. Their arguments were not primarily theological but rather philosophical criticisms which charged that Averroes, particularly in his Psychology, failed to understand Aristotle and misrepresented Aristotle’s thought in his confused exposition of Aristotle’s Psychology. This is so well-known to us in our own day that Averroes’ name has even made its way into Copi’s elementary logic text as part of an exercise using a quotation from Duns Scotus in which this Islamic philosopher is called “That accursed Averroes.” Scotus remarks that

… [A]ll philosophers commonly assign “rational” as the difference that properly defines man, meaning by “rational” that the intellective soul is an essential part of man. In fact, to put it briefly, no philosopher of any note can be found to deny this except that accursed Averroes (ille maledictus Averroes) in his commentary on De anima, Bk III, where his fantastic conception, intelligible neither to himself nor to others, assumes the intellective part of man to be a sort of separate substance united to man through the medium of sense images.

In a general way Averroes’ name has been associated with naturalistic thought labeled “Latin Averroism” which appeared to deny the personal immortality of the soul, to follow Aristotle regarding the eternity of the world, and to place the rational in priority to the religious. Not at all surprisingly, such an understanding of Averroes’ thought sees him as a personification not only of religious unorthodoxy well deserving of suppression and correction in the cultural contexts of Medieval Christianity and Islam, but also of philosophical foolishness and of heresy against the Aristotelian tradition.

Such a view of the work of Averroes, however, is in part a consequence of a failure to appreciate fully the depth of reflection which Averroes brought to Aristotelian texts and philosophical principles. His account of the relationship of philosophical Psychology and metaphysics and of how Psychology provides key principles both for the establishment of the science of Metaphysics and for the explanation of separate intellect. That account provides evidence of a sophisticated mind at work weaving from Aristotelian threads a coherent cloth of metaphysical teachings. And what provides the basis for this account is nothing other than his controversial and seldom understood doctrine of the separate Material Intellect which is one for all humankind. The present article concerns that teaching on separate intellect and aims to show how Averroes can assert in his Long Commentary on the De Anima and in his Long Commentary on the Metaphysics that principles for the science of Metaphysics are established in the science of Psychology, a science which is itself a branch of Natural Philosophy or Physics.


At the beginning of chapter 1 of book VI of his Metaphysics, Aristotle states that, “We are seeking the principles and the causes of the things that are, and obviously of things qua being.” Setting forth a division of the sciences into practical, productive and theoretical, he explains that while the theoretical science of mathematics deals with its objects as immovable and as separable from matter, “natural science deals with things which are inseparable from matter but are not immovable.” But “first science deals with things which are both separable and immovable.” He goes on to assert the existence of three theoretical sciences, namely mathematics, natural science and theology, and to assert the existence of a highest science dealing with the highest genus. This is First Philosophy, which is universal in scope. But this First Philosophy will be the theoretical science of theology only if its subject matter, separate substance, can be shown to exist. As Aristotle puts it there: “If there is no substance other than those which are formed by nature, natural science will be the first science; but if there is an immovable substance, the science of this must be prior and must be first philosophy, and universal in this way, because it is first. And it will belong to this to consider being qua being-both what it is and the attributes which belong to it qua being.”

In his comment on this in the Long Commentary on the Metaphysics, Averroes explains Aristotle’s reference to theology by noting that divine things are those in whose definition reference is made to God and that if there is a divine science, that science concerns what is in a separate nature. And he also goes on to endorse Aristotle’s view that “if there were no other substance than the sensible, there would be no science prior to Natural Science.” But “if there is some immobile substance, that substance is first and its science is a universal science and First Philosophy.” Hence, Averroes clearly holds to the necessity of establishing the existence of substance which is separate and not the subject of the science of Physics or Natural Philosophy if there is to be a third theoretical science, the science which he and the tradition knew as Metaphysics. If this cannot be accomplished, First Philosophy will turn out to be Physics or Natural Philosophy. Where is it established that there is such a nature? As is well-known, Averroes rejects the approach to Metaphysics of Avicenna who takes being as divided into the necessary and the possible as a starting point. Instead, for Averroes, as for his master, Aristotle, it must be the science of Physics or Natural Philosophy that provides the reason or basis for the science of Metaphysics.

The search for the establishment of the subject matter of Metaphysics, then, takes us to the Physics of Aristotle and Averroes’ exposition. Yet exactly how Aristotle’s arguments in books VII and VIII of his Physics are to be construed is a difficult matter. The arguments of the Physics can be read as leading directly to the famous account of the divine found in Metaphysics XII, that is, the account of the necessity of the existence of an unmoved mover who is separate in existence from the world, purely actual, ultimately responsible for the motions of the heavens by way of final causality, and there characterized as a substance essentially self-thinking thought in actuality.lt Yet such a reading of the Physics of Aristotle is far from easily established, for it is not unreasonable to hold that the God of the Physics is much different from the God of the Metaphysics. Aristotle’s arguments in his Physics seem to lead, not to a cause of motion which acts by way of final causality as in the Metaphysics, but rather to a first mover who is a mover by way of motion or efficient causality. Moreover, as Herbert Davidson and others have pointed out, insofar as Aristotle holds in the Physics that the eternal motion of the heavens requires infinite power and that infinite power cannot be held within a finite body, Aristotle does provide a proof for an “incorporeal first mover beyond the heavens.” Note, however, that Aristotle’s conclusion is minimalist in that he does not endeavor in the Physics to give a more detailed account of the essential nature of this “god” or first mover, since Physics deals with enmattered things and their consequent attributes. Does this account satisfy the requirements of Metaphysics VI 1 for the establishment of Metaphysics as First Philosophy? It would appear to do so, for the existence of an immovable substance is established even if it is only understood through its activity as a cause of infinite power bringing about the eternal circular motion of the heavens, while its own nature as an immaterial entity remains something not fathomed in Physics.

Averroes’ position on this is similar and involves the contention that the natures of the celestial bodies are altogether different from those of bodies of the sublunar realm. While sublunar bodies are subject to dissolution because they are composites of form and matter such that the matter or substratum exists in virtue of the actuality of its correlative form, the substratum of the spheres is not subject to dissolution but rather is existent in its own right without any destructive contrariety in it.ls In contrast to the matter of this sublunar world, as Davidson puts it, “The heavens must instead be construed as a body of a completely different type, consisting in the association of a simple matter-like substratum in motion, and an independently existing immaterial form moving the substratum. The matter-like substratum exists necessarily by virtue of itself, and the form is a source of infinite power whereby the substratum moves eternally.” On this account of the teaching of Averroes, then, the relationship of the substratum of the sphere and the incorporeal form moving it is one of an association like that of a soul with a body albeit with the important difference that this celestial soul is not in the celestial body as a sublunar soul is in a sublunar body. But just what is the nature of this association? How does this association cause the celestial body to move? And just what is the nature of this separate immaterial form? The science of the soul or Psychology, a branch of Physics, is where we must turn for answers to these questions.


In the opening lines of his de Anima, Aristotle makes the following statement:

Holding as we do that, while knowledge of any kind is a thing to be honoured and prized, one kind of it may, either by reason of its greater exactness or of a higher dignity and greater wonderfulness in its objects, be more honourable and precious than another, on both accounts we should naturally be led to place in the front rank the study of the soul. The knowledge of the soul admittedly contributes greatly to the advance of truth in general, and, above all, to our understanding of Nature, for the soul is in some sense the principle of animal life.

For Averroes in his Long Commentary on the De Anima of Aristotle, due to the nobility of the subject and the demonstrative power of Psychology or the science of the soul, this science surpasses other sciences, except for divine science, and so we must hold that the science of the soul comes before the other sciences; and for this reason we placed it in a position of priority among all subjects of inquiry.” But there is much more to the value of Psychology for Averroes. You should be aware that the science of the soul is found to be helpful to the other sciences in three ways. First, inasmuch as it is part of that science, indeed the noblest of its parts-and this is the relationship it has to natural science. For living things are the noblest of generable and corruptible bodies, but the soul is nobler than all else in living things. Secondly, because it supplies more principles for more sciences, for example, for moral science-that is, [the science] of governing states-and for divine science. For from this science moral science gets the ultimate end of human beings considered as human beings and the knowledge of what their substance is. The metaphysician gets from it the substance of his subject. For here [in the science of the soul] it will be explained that the separate forms are intelligences, and also many other things concerning the knowledge of states consequent upon intelligence considered as intelligence and intellect. And thirdly, it is generally helpful and enables the acquisition of confirmation regarding first principles, since from [this science] we acquire knowledge of the first causes of propositions, and knowledge of anything through its cause is more certain than [knowledge] only of its own being.

Thus, Psychology helps us understand the power of soul in living things. It also supplies principles for several sciences, for moral science which is a branch of politics by making known human nature and its end, and also for Metaphysics for which it provides an understanding of the nature of intellect and separate intelligence. And, third, Psychology provides an understanding of human epistemological powers and functions.

For Averroes, it is Psychology which is responsible for supplying key principles for the establishment of the science of Metaphysics, by establishing in a way different from that of Physics that there exist separate forms and that these separately existing forms are intellectual in nature. It also is able to contribute to an understanding of the natures of the celestial bodies and their motions. What Averroes has in mind is the science of Psychology’s establishment of the existence of the Agent Intellect and of the existence of the Material Intellect as separately existing substances.

The Material Intellect is defined as that which is in potency all the intentions of universal material forms and is not any of the beings in act before it thinks [any of them]. Since that is the definition of the Material Intellect, it is evident that in its own case it differs from prime matter in this respect: it is in potency all the intentions of the universal material forms, while prime matter is in potency all those sensibles forms, not something which knows or discerns. And the reason why that nature is something which discerns and knows [distinguens et cognoscens] while prime matter neither thinks nor discerns, is because prime matter receives diverse forms, namely individual and particular forms, while this [nature] receives universal forms. From this it is apparent that that nature is not this, nor a body nor a power in a body. For, if this were so, then it would receive forms according to their diversity and particularity; and if this were so, then the forms existing in it would be intelligible in potency, and thus it would not discern the nature of the forms inasmuch as they are forms, as it is a disposition in relation to individual forms, be they spiritual or corporeal. For this reason, if that nature which is called the intellect receives forms, it must receive forms by another mode of reception than that by which those matters receive the forms whose determination by matter is the determination of prime matter in them. And for this reason it is not necessary that it be of the genus of those matters in which the form is enclosed, nor that it be prime matter itself. Since, if this were so, then the reception in these would be of the same genus; for the diversity of the received nature causes the diversity of the nature of the recipient. This, therefore, moves Aristotle to set forth this nature which is other than the nature of matter, other than the nature of form, and other than the nature of the composite.

The Material Intellect has a certain potency in it insofar as it is able to have in it the intelligible forms of material things of the world in an immaterial way such that what we call knowledge of the universal is present in the intellect. When a form is in act in a particular material thing in the physical world, it exists in a material way as a particular and as such it is intelligible only in potency. That is, for it to be intelligible in act, it needs an intellect to grasp it as intelligible, it has to come to exist in an intellect as intelligible in accord with the nature of that intellect. The need for an immaterial reception of universal forms in knowing requires that what receives them be a separate intellect and yet be something which is capable of reception, that is, have a potency for the reception of immaterial forms. These intelligibles in act in the separate Material Intellect are the referents for the notions expressed by us in universal propositions of science.

Averroes’ assertion of the necessity of the existence of this separate Material Intellect is a position he came to late in life after long years of struggle over the issue of the intellect. His mature account follows in part from two central philosophical propositions resulting from his study of the tradition. First, as we have seen above, if the reception of an intelligible in act were to come about as a reception into this or particular individual, what is received would be something else, that is, something which is not an intelligible in act but rather an intelligible in potency. But in order to understand, that is, to have the intelligible in act in it, the Material Intellect cannot be a body or a power in a body since that would make it this. Secondly, if the intelligible in act were in many intellects, the intelligible in act would be many intelligibles in act, not one; but the intelligible in act must be one so that there is a single intelligible which is common referent for individuals forming propositions of science, so that science is possible. A plurality of material intellects, then, is impossible. The material intellect has to exist as a single, separate immaterial being of an intellectual sort, not as some particular material individual. This single material intellect is shared by all human beings and is that in virtue of which they are called rational.

In his comment to text 5 in Book III of the De Anima, Averroes remarks that the investigation into the nature of intellect yields an understanding of the material intellect as intellect and yet as having a receptive potency within it. Explaining his doctrine by analogy, he states that just

as sensible being is divided into form and matter, intelligible being must be divided into things similar to these two, namely into something similar to form and into something similar to matter. This is [something] necessarily present in every separate intelligence which thinks something else. And if not, then there would be no multiplicity in separate forms. And it was already explained in first philosophy that there is no form absolutely free of potency except the First Form which understands nothing outside Itself. Its essence is its quiddity (essentia eius est quiditas eius). Other forms, however, are in some way different in quiddity and essence. If it were not for this genus of beings which we have come to know in the science of the soul, we could not understand multiplicity in separate things, to the extent that, unless we know here the nature of the intellect, we cannot know that the separate moving powers ought to be intellects.

That is, this division in intellectual entities of what is analogous to form and of what is analogous to matter, or of act and potency, is discovered in Psychology. It is then used as a principle in understanding the natures of all the immaterial intelligences. Potency must be present in any separate intelligence which is capable of knowing anything outside itself. For insofar as it is an intelligence with itself as its object, it need have no potency. But insofar as it is in potency for knowing something other than its own essence or nature, namely the First Cause which is the final cause of all, it must have a certain “materiality” or potency for receiving a form other than its own from outside itself as it strives to understand the First Cause. While essentially active without potentiality for any change within them, the immaterial intelligences must nevertheless be in a relation of knowing vis a vis the First Cause. As such, for them there is less than complete and perfect unity of essence and quiddity.


The establishment of separate entity in Natural Philosophy or Physics allowed for the certification of the science of Metaphysics. Now the determination of the existence of separate intellect in Psychology allows for the conclusion that separate intellect is immaterial actuality and separate from the body in existence. It further allows for the understanding of how potency can be present in an immaterial intellect. But does it also allow us to conclude that “the separate moving powers” from the Physics “ought to be intellects,” as Averroes remarks in the passage from De Anima III Averroes certainly seems to think so.

This was unknown to many modern thinkers to the extent that they denied what Aristotle says in the eleventh book of the First Philosophy, that the separate forms moving the bodies must be in accord with the number of celestial bodies. To this extent knowledge of the soul is necessary for knowledge of First Philosophy. And that receptive intellect must think the intellect which is in act. For, while it thinks material forms, it is more befitting that it think immaterial forms. And what it thinks among separate forms, for example, the Agent Intellect, does not impede it from thinking material forms.

What Psychology does by means of the discovery of the separate agent and material intellects is to supply Metaphysics with important principles for the understanding of the conclusions of Natural Philosophy. Now the movers of the heavens, the separate intellectual souls or intellects, can be understood as different in essence from one another in virtue of differences in their levels of actuality and potency, something reflected in the different movements they cause in the heavens. Only the “First Form” or God is to be understood as pure intellectual actuality completely free of potency.

Such is the position of Averroes in his Long Commentary on the Metaphysics of Aristotle as well. There he remarks: From this it is fully clear that these celestial bodies are alive and that among the powers of soul they have only intellect and the power of desire, i.e. [intellect] which causes motion in place. This is perhaps evident from what I say, for it has been explained in the eighth book of the Physics that what causes motion belonging to the celestial bodies is not in matter and is a separate form. And it was explained in the De Anima that the separate forms are intellect. So, consequently, this mover is an intellect and is a mover insofar as it is an agent of motion and insofar as it is the end of motion.

Now we need to note that this conclusion does not strictly follow from what has been set forth here. As Charles Genequand points out in the introduction to his translation of Averroes’ commentary on Aristotle’s Book Lambda of the Metaphysics, “Combining indications drawn from the eighth book of the Physics and the third of the de Anima, Ibn Rushd tries to prove that the first mover is itself an intellect. The argument,” continues Genequand, “is not quite convincing because what the de Anima shows is that the intellect is a separate form, not that any separate form is an intellect as Ibn Rushd says (1593,14-1594,3).” That is to say, the syllogism is not complete according to Genequand who believes the argument fails. That the mover is a separately existing immaterial actuality does not mean without further explanation that it must be an intellect, as happens in the argument of the De Anima where instead the argument moves from intellectual operations to the necessity of intellect being separate. This conclusion, however, can be drawn on the basis of an additional premise or assumption. Where are we to find the needed principle?

The reduction of ota to form and actuality in Metaphysics Zeta and Eta makes it clear that being is the actuality of form and intelligibility for Aristotle and for Averroes. Consequently, the argument of the Physics to a separate associated mover as an immaterial actuality is an argument to a being whose nature is form. As such, this immaterial actuality is a being and an intelligible object or form. Now, in the case of immaterial intelligible objects, the De Anima has shown for Averroes that a separate intelligible object, insofar as it is actually intelligible, must exist in an intellect. Hence, it is not enough to conclude that there exists a separate intelligible object; rather, it must be concluded that an intelligible form existing as a separate actuality must in its very nature be existent in an intellect. This understanding is confirmed in the commentary on book Lambda of the Metaphysics where Averroes remarks:

Since conceptualization by intellect, which is an activity of intellect, is the intellect itself and the intellect is the intelligible itself according to what has been explained in the De Anima, he said “The intellect is from the intelligible,” meaning that the intellect in its essence and substance is only from the intelligible. Later Averroes explains that there are two sorts of intelligibles, the intelligibles of matter which are intelligible in relation to something else (namely, a knower in virtue of which these potential intelligibles become actually intelligible) and the intelligibles of the forms which are understood in their own right. These forms which are intelligible in themselves are substantial and are simple. And by simple here is meant that the form is free of matter and is not a composite. Hence, an existing separate form as intelligible is an intelligible in act not dependent in its intelligibility upon a relation to something else. As such it is then an intelligible for itself and so it is also intelligent or an intellect in its own nature. Hence, contrary to the belief of Genequand, Averroes’ argument is complete. Any actually existing separate form must be an intellect.

What about the celestial bodies and their relationship to their associated intellects? As Averroes understands Aristotle, the celestial bodies can only equivocally be said to have matter and soul because our use of those notions is based upon our experience in the sublunar realm where soul gives actuality to matter and the two principles make up one entity. Analogies based on what is learned from the science of Psychology have only limited value. In the case of celestial bodies, the body is not properly speaking matter actualized, that is, animated by separate principle, soul. Rather, the celestial bodies which we perceive in the heavens are immediately substantially existent per se and eternal since they have matters which do not have potency for substantial change. Celestial bodies move eternally and so have desire, but they do not have sense perception and do not have imagination and the cogitative power as do sublunar rational animals, that is, as do human beings. As Gerhard Endress puts it, for Averroes “the senses and the organs of sense-perception exist only in mortal animals, ‘for the sake of preservation.’ But the relation of the heavens to their principles of existence and movement is different from the relation between bodies and souls in the sublunary world, making it possible to forego the intermediary of imagination postulated by Avicenna.” Thus, each of the eternally moving celestial bodies has associated with it a separate intellectual soul which is fully immaterial. By means of its association, the celestial body moves out of desire which is intellectual in nature, that is, by contemplative desire aroused by conceptualization by intellect (tasawwur bi-l-`aql) of intelligibles. And, as we have seen, since the motion of the celestial body is eternal and necessary, according to Aristotle and Averroes, that which makes the motion to occur, separate intellect, must also exist eternally and must have an immaterial and imperishable nature as the form of the celestial body. This sort of exposition draws upon the science of soul or Psychology, insofar as it uses philosophical Psychology’s understanding of desire, of conceptualization by intellect, and of corporeal human beings’ linkage to separate intellect in conceptualization by intellect in order to understand the association of separate intellects with eternally moving celestial bodies.


The purpose of this article has been to explain how it is that Averroes can assert in his Long Commentary on the De Anima and in his Long Commentary on the Metaphysics that principles of the science of Metaphysics are established in the science of Psychology, a science which is itself a branch of Natural Philosophy or Physics. We began with a consideration of the requirements for the assertion of the existence of a science of First Philosophy as Metaphysics in Book VI chapter 1 of Aristotle’s Metaphysics. There it was held that Natural Philosophy would be First Philosophy if it could not be established that there exists separate or immaterial being. Next we understood Averroes to have proved the existence of an immaterial separate form as cause of the motion of the celestial substratum. This was sufficient to satisfy the needs expressed by Metaphysics VI 1 for the existence of an immaterial entity, and allowed that there is a universal science of being qua being which deals with things beyond those of Physics, namely the science of Metaphysics. Yet the nature of this immaterial form was not clear from the argument of the Physics. It was here that Averroes understands the science of Psychology to make an important contribution to the principles of Metaphysics. It is in Psychology that human intellectual understanding is studied and found to require the existence of the separate Agent Intellect for the account of the coming to be of knowledge as that knowledge manifests itself in human beings. In this, then, intellect and separate being are established as one, that is, it is shown on the basis of the analysis of human Psychology that intellect must exist and that this intellect must be separate from the human being in existence. Moreover, it is also established on the basis of the analysis of human knowing that there exists potency in those things called intellect, thanks to the argument for the existence of the Material Intellect. These key contributions from Psychology to the principles of the science of Metaphysics were explicitly recognized by Averroes in book Lam of his Commentary on the Metaphysics of Aristotle.

Perhaps the greatest value of this undertaking, however, is to clarify in some small way the understanding of Averroes concerning the interrelationship of the sciences of Physics, Metaphysics and Psychology. In light of the role played by Psychology in establishing principles for Metaphysics, a number of otherwise seemingly non-Aristotelian doctrines can now be seen in an Aristotelian context. One such doctrine is the plurality and hierarchy of separate intelligences or intellects discussed in Aristotle and Averroes. Aristotle never provided a sufficient account regarding the natures of the plurality of separate intellects or forms in Metaphysics XII. Certainly in the context of Aristotle’s thought there, it is impossible to conceive of these pure forms and pure actualities as having any potency at all. Rather, each was a self-contained monad and only by reference to the motion it caused and by an argument from analogy could Aristotle put one of these intellects first as the highest god.

For Averroes, however, the intellects are ranked by differences in their potentiality, not potentiality in being, but potentiality in knowing. That such potentiality existed in some way in separate intellects Averroes might have taken as a given principle or assumption if he were more a follower of the Neoplatonic tradition. In that tradition as reflected in the Arabic materials derived from texts of Plotinus and Proclus, lower intellects are illuminated by higher intellects in a species of participation. The very possibility of being receptive to illumination indicates some sort of potentiality. But for Averroes the assumption of philosophical doxa or tradition does not constitute philosophical proof. Rather, he argued for his similar position on the basis of understandings of intellect demonstrated in Aristotelian Physics, Psychology and Metaphysics. That is to say, his account of the natures and hierarchy of separate intellects is not Neoplatonic but Aristotelian. And in the course of constructing his argument he insisted on the importance of the role of human rationality and the investigation of it in the establishment of principles of the science of Metaphysics. These principles are established in his exposition of his controversial and difficult doctrine of the separate Material Intellect, a doctrine philosophically argued by him using Aristotelian philosophical principles.