Averroës, the last of the great Islamic philosophers, lived roughly one hundred fifty years after Avicenna, his philosophic rival, and about three generations after al-Ghazzali, the greatest of Muslim theologians. In his controversy with these two men, he concerned himself primarily with the defense and purification of Aristotle, whom he followed as closely as he could. Because he, too, accepted such spurious works as Theologia Aristotelis (derived from Plotinus), his interpretation is still permeated by Neoplatonic elements, but to a lesser extent than that of Avicenna. The success of his endeavor is indicated by the fact that he was known to Scholastic writers as the Commentator and that no less a person than Saint Thomas Aquinas had him constantly at hand as he wrote his Summa contra gentiles (c. 1258-1260; English translation, 1923) and his various commentaries on Aristotle.

The Incoherence of the Incoherence was written in reply to mystic al-Ghazzali’s book, Tah-fut al-falsifa (1095; Incoherence of the Philosophers, 1958), in which al-Ghazzali attacked the philosophers, and in particular Avicenna, for advocating doctrines that were incompatible with their faith. As the title of his own book suggests, Averroës came to the defense of the philosophers. Adopting a position similar to that of the later medieval thinkers who distinguished between revealed and natural theology, Averroës scrupulously avoided denying any tenet of his faith; nevertheless, he sided firmly with the philosophers. His interpretations of religious doctrines were so far removed from those of the theologians that even though he was studied carefully by Hebrew and Christian philosophers, he was not recognized to any great extent by his Islamic contemporaries. Averroës’s book plays a very important role in the long controversy between the philosophers and the theologians because it is concerned chiefly with the nature and existence of God and with the relationship between God and the cosmos. Averroës does not spell out his position in detail, for he agrees on the whole with the earlier commentators on Aristotle and with the version of Aristotle he receives from them. In particular, he agrees largely with Avicenna, disagreeing on those points, and they are important points, where he thinks Avicenna departs from Aristotle.

A First Cause and Time

Averroës agrees with Aristotle that there is a First Cause, and he accepts a modified version of Avicenna’s proof from contingency. Objects whose existence is contingent rather than necessary must have a cause. If the cause is itself contingent, and if its cause is contingent, and so on, there would be an infinite regress and therefore no cause at all, a conclusion that, it can readily be seen, denies the assumption that contingent objects must have a cause. Hence, any series of contingent objects must be preceded in existence by a necessary cause that is either necessary through another or necessary without a cause—necessary in itself. However, if we have a series of causes each of which is necessary through another, once more we have an infinite regress and thus no cause. Hence, any series of causes necessary through another must depend on a cause necessary in itself—a First Cause.

The nature of this First Cause and of the way in which it causes is illuminated by Averroës’s discussion of creation. Averroës agrees with the philosophers against al-Ghazzali that the world was not created in time. The philosophers had argued that if the world was created in time, it was created directly or indirectly by God, because an infinite regress of causes is impossible. If God created it in time, then he acted at a time and therefore underwent a change in time; but unquestionably, this is an impossible state of affairs because God is perfect and changeless. To al-Ghazzali’s objection that God did not act in time but decreed from all eternity that the world should come into being at a certain time, Averroës replies that even if God had so willed from all eternity, he must also have acted at the time of creation in order to implement his decision, for every effect must have a contemporaneous cause. Consequently, the philosopher’s objection cannot be avoided. It can be shown similarly that the cosmos is incorruptible; that is, that there is no time at which it will come to an end, for this too would require a change in God. Change occurs only within the world and then only when one thing is changed into another. The world itself is eternal and everlasting.

Al-Ghazzali had already attacked Avicenna on this point, asserting that the followers of Aristotle now have a problem on their hands, for they must give some account of how an eternal First Cause produces things that have a beginning in time. The...

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Averroës then considers the question raised by al-Ghazzali as to how it is possible for the plurality in the world to arise from the Mover, who is simple. Avicenna had argued that only one thing can emanate from God, but that this thing, the First Intelligence, is able to generate more than one thing by contemplating both itself and the Mover. Averroës replies, first, that because thought and its object are identical, the Intelligence is really identical with its thought of God and with its thought of itself and, therefore, that these thoughts are identical with each other. Hence, there is no plurality of thought and no plurality of creation.

Second, he says that when Avicenna insists that only one thing can come from God, he is thinking of the Supreme Intellect as if it were a finite empirical one, but this concept is a mistake. Because our intellect is limited by matter, any particular mental act can have only one object, but because God is not so limited he can think all things even though his simplicity and changelessness preclude a plurality of acts. If it is argued that to think of all things is to have many thoughts and that because thinker and thought are identical, God must be plural, Averroës replies that when God thinks all things, he does not think them discursively as people do. People either entertain images, a process that unquestionably involves spatial apprehension and thus spatial plurality, or they understand concepts by genus and species, a process that again introduces plurality. In either case, because people apprehend the object of thought by abstracting it from its material context, they apprehend it imperfectly. God, who is perfect, does not apprehend the nature of things in these ways and therefore does not apprehend them as either individual or universal. In some manner that people do not understand, he comprehends that which is plural to people but does not comprehend it as numerically plural. (This is a particular application of the general principle that any property or capacity attributed to God must be attributed only by analogy.) God, then, is the source of all plurality even though he is simple and changeless.

The Avicennian Cosmology

Averroës accepts the Avicennian cosmology in its general outlines. The First Mover produces a number of pure intelligences that may produce others and that cause the motions of their respective spheres or, in the case of the Agent Intellect, preside over generation and corruption in the sublunar world. The Mover is the efficient cause of these intelligences, producing them by means of a power that it emanates, and the final and formal cause insofar as it is the thing they seek to emulate. They in turn are the efficient, final, and formal causes of the motion of the spheres. Averroës agrees with Avicenna that though prime matter is not created, the existence of material things depends upon the Mover who is the source of the forms and also the agent, final, and formal cause of the manifestation of any form in matter.

However, despite this agreement Averroës disagrees with Avicenna on a number of points. Some, such as the number of intelligences (more than forty), and the nonlinear order of the intelligences (the Mover may have produced all of the intelligences of the principle spheres directly) are unimportant, but others are crucial. Averroës insists that the intelligences really are simple in that they do not contemplate themselves in several essentially different ways. The spheres are not composites of soul and body even though they are animate, and God is the source of plurality. Consequently, God does not function as Avicenna says he does. Whether...

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Existence and Essence

Another historically important feature of Averroës’s philosophy is his rejection of Avicenna’s sharp distinction between essence and existence. Avicenna had insisted that except in the case of God, existence is an accident that happens to an essence. For Avicenna, existence is a condition that must be satisfied by an essence before it can occur outside a mind, a property that must be added to it. Therefore, the existence of a material object does not stem from its essence, but from what happened to its essence. However, Averroës insists that the very being of an existent thing is its essence, that its being depends upon the essence and not upon what happens to the essence. For him, the terms “being” and “existence” are not verb terms, but substantives applied primarily to the object itself and secondarily to the essence that makes it the sort of thing it is. Because the object is a being or existent in virtue of its essence, it is impossible to separate essence and existence save in thought. The essence itself may be regarded as an existent in a secondary sense of that term, but in this case it is impossible to separate essence and existence even in thought.

This difference between the two men is reflected in their views, inasmuch as Avicenna is very much concerned with how things come into existence and Averroës shows himself to be more concerned with the manner in which things change. Thus, in their proofs of the existence of God,...

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(Student Guide to World Philosophy)

Additional Reading

Copleston, Frederick. A History of Philosophy: Medieval Philosophy. Garden City, N.Y.: Doubleday, 1962. Provides a good overview of medieval Islamic philosophy, and the contributions made by Averroës in particular.

Davidson, Herbert A. Alfarabi, Avicenna, and Averroes on Intellect: Their Cosmologies, Theories of Active Intellect, and Theories of Human Intellect. New York: Oxford University Press, 1992. A significant study of the most important Arabic philosophers from the medieval period.

Hitti, Philip K. Makers of Arab History. New York: St. Martin’s...

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