'Averroism', 'radical Aristotelianism' and 'heterodox Aristotelianism' are nineteenth- and twentieth-century labels for a late thirteenth-century movement among Parisian philosophers whose views were not easily reconcilable with Christian doctrine. The three most important points of difference were the individual immortality of human intellectual souls, the attainability of happiness in this life and the eternity of the world. An 'Averroist' or 'Radical Aristotelian' would hold that philosophy leads to the conclusions that there is only one intellect shared by all humans, that happiness is attainable in earthly life and that the world has no temporal beginning or end. Averroists have generally been credited with a 'theory of double truth', according to which there is an irreconcilable clash between truths of faith and truths arrived at by means of reason. Averroism has often been assigned the role of a dangerous line of thought, against which Thomas Aquinas opposed his synthesis of faith and reason. The term 'Averroism' is also used more broadly to characterize Western thought from the thirteenth through sixteenth centuries which was influenced by Averroes, and/or some philosophers' self-proclaimed allegiance to Averroes.
Averroes, the twelfth-century Muslim commentator on Aristotle, exercised a strong influence on Latin scholastics from about 1230 onwards (see Ibn Rushd). Around 1270, the derogatory term Averroistae ([too ardent] followers of Averroes) began to be used, principally to characterize adherents of the view that there is only one shared human intellect. In 1277 the Bishop of Paris, Etienne Tempier, accused unnamed masters of arts of the University of Paris of paying more attention to heathen philosophers than to Christian revelation, and of behaving as if there were two truths, one of philosophy and another of faith. The theory of one shared intellect was among the 219 theses the bishop condemned. A generation later, Ramon Llull launched a series of attacks on university philosophers whom he saw as continuators of the lines of thought condemned in 1277, and used the term Averroistae to describe these philosophers.
Based on this medieval use of Averroistae, the term 'Averroism' was introduced in nineteenth-century historiography of philosophy. Averroism was conceived of as a movement of thirteenth-century thinkers faithful to Averroes, proclaiming that the same proposition could have different truth values in philosophy and theology, so that there was an unbridgeable inconsistency between philosophy and faith. Averroism was cast as a sinister force (a precursor of modern atheism), valiantly combatted by Albert the Great and Thomas Aquinas, notably in the latter's De unitate intellectus (On the Unicity of Intellect) and De aeternitate mundi (On the Eternity of the World). Twentieth-century historiography came to identify three main currents in late thirteenth century philosophy: first, Augustinianism, mainly represented by Franciscan thinkers, which combatted the growing influence of Aristotelian philosophy (see Augustinianism); second, Averroism, which took a radically Aristotelian approach to philosophical problems, even though this must lead to conflict with Christian faith; and third, the current led by Albert the Great and Aquinas, who produced a synthesis of Aristotle and Christian faith (see Aristotelianism, medieval).
Early in the twentieth century, it was commonly assumed by historians that almost all the 219 theses condemned in 1277 were of Averroist provenance, and since there is medieval evidence that the main targets of the condemnation were Boethius of Dacia and Siger of Brabant, they were thought to have embraced most of the 'heterodox' opinions. Siger, who is known to have engaged in university politics, began to be seen as the leader of an Averroist party at the University of Paris in the 1260s and 1270s.
Subsequent research has undermined the foundations for the historiographical scheme in which a thirteenth-century 'Averroism' belongs. First, the majority of the theses condemned in 1277 were not inspired by Averroes. Moreover, scholars often apply the label 'Averroist' also to later philosophers who were influenced by Averroes or continued the views of writers such as Siger of Brabant: examples include the Parisian masters Ferrandus Hispanus in the late thirteenth century and John of Jandun in the early fourteenth century, and to a long list of Italian writers from Gentile da Cingoli in the 1290s and Angelo d'Arrezzo in the early fourteenth century to Agustino Nifo in the early sixteenth century. Some of these writers did indeed defend Averroes' views whenever possible, but such loyalty towards Averroes had not been a characteristic of the men who were condemned in 1277.
When these facts became apparent to historians of philosophy, they began to replace 'Averroism' with 'radical Aristotelianism' or 'heterodox Aristotelianism' as the name of this supposed thirteenth-century school of thought. However, so many historical misunderstandings and ideologically motivated judgments cling to all these labels that they are, in the 1990s, being abandoned. Yet, there are some interesting problems that these labels were meant to help explain, and which still have an important place in medieval philosophy.
In the later half of the thirteenth century, there was a common conviction that some philosophical tenets were inconsistent with Christian doctrine as standardly understood. 'Philosophical' in this connection means Aristotelian on the then standard interpretation of Aristotle, which leaned heavily on Arabic works including the writings of Avicenna and Averroes, and the Liber de causis (see Aristotelianism, medieval; Liber de causis).
Three issues stood in the foreground in the conflict between reason and faith: first, whether all humans share a common intellect (monopsychism); second, whether happiness is attainable in this life; and third, whether the world had a temporal beginning.
Monopsychism: It was generally accepted that the intellect (that is, the intellective soul) has both an active component, 'the agent intellect', which forms universal concepts on the basis of particular pieces of information provided by the senses, and a passive component, usually called the 'possible intellect', which is the initially blank wax tablet on which the active component leaves its imprints in the form of concepts and knowledge acquired. The question was, are the agent and possible intellects genuinely different, and if not, does each human being have its own intellect, or is there only one for all to share?
There was a tradition of considering only the agent intellect to be an extra-human separate substance, responsible for humans' shared conceptual apparatus; in this view, the individuality of each person's possible intellect explains why we do not share all our thoughts. One version of this view was held by Roger Bacon. By the 1260s, however, this radical separation of the agent and possible intellects had become rather old-fashioned. The main disputants of the time agreed that the two intellects are one substance, but they disagreed about whether that substance is extra-human. Averroes, as he was commonly understood after about 1250, taught that the intellect is a single impersonal substance with which individual souls enter into contact via their mental representations (phantasms) of extramental things; the intellect uses the phantasms as a basis for abstraction. Modern historiography has applied the term 'monopsychism' to this doctrine, which was attacked by Aquinas in his De unitate intellectus.
Monopsychism allows for the irrational part of a human soul to be destroyed on death without this affecting the intellect. Like the old assumption of a separate agent intellect, it also accounts for the ability of human beings to share knowledge; but it offers no convincing answer to the objection that if this is the case, then no thought belongs to one individual rather than another. During at least one phase of his career, Siger of Brabant accepted monopsychism, but believed that it was possible to save some private thought for the individual by making the operation of the intellect in a particular human depend on representations (intentiones imaginatae) with an origin in sensation unaided by intellect. In his somewhat obscure attempts to explain how the individual 'plugs into' (continuatur) the supra-individual intellect, Siger relied heavily on Averroes.
Contemporaries were alert to the Averroistic theory's inability to explain how all humans can share an intellect without sharing all thoughts. However, to medieval thinkers the gravest objection against monopsychism was that it left no individual rational soul to carry responsibility for a deceased person's acts. Nor was it easy to see how an immaterial intellect could fail to be eternal, which was contrary to Christian doctrine that God creates new souls every day and that they are in principle perishable (God could annihilate a soul if he wished). Nonetheless, for the next couple of centuries most philosophers seem to have held that monopsychism was one of the few rationally defensible views about the nature of the intellect, while standard Church doctrine continued to require the intellect to be both the form of the body and capable of separate, individual, existence. The issue was still very much alive in 1513 when the Fifth Lateran Council explicitly condemned the view that the intellective soul is either mortal or only one for all people, and explicitly asserted that it is the form of the human body, immortal, and as many in number as are the bodies into which it is infused.
Happiness in this life: Around 1260-70, masters from the Faculty of Arts at the University of Paris often expressed a great optimism about the attainability of happiness in this life. Their views strongly resemble those of ancient Neoplatonism, but the strongest impetus came from Arabic philosophy rather than directly from ancient sources (see Neoplatonism; Neoplatonism in Islamic philosophy). The way to happiness was thought to consist in an intellectual ascent to the contemplation of ever higher beings, culminating in contemplation of the First Cause and the (temporary) union of one's possible intellect with the source of intellectual understanding, the agent intellect; In this tradition, the agent intellect was thought to be a separate substance and not identical with God. Such a state of intellectual bliss was held to be the fullest actualization of a person qua human, that is, a rational being.
This line of thought would seem to permit the construction of a naturalistic ethics with no need for either divine revelation or an individual life after death in order that human beings may reach their ultimate goal and happiness. Boethius of Dacia did indeed hold that a natural philosopher must deny the resurrection of the dead, and this was to be a common view for a long time. However, there is little evidence that anyone really wanted to abolish the belief in a second life. The philosophers' point was simply that while it is known through revelation that supranaturally there will be such a life, a claim to that effect cannot be incorporated into a consistent theory of nature (see Natural philosophy, medieval).
Eternity of the world: Before the 1260s there had been some attempts to interpret Aristotle as if he accepted a temporal beginning of the world. Perhaps the first such attempt was made by William of Conches in the twelfth century. However, as Robert Grosseteste noted in the 1230s, such attempts had failed and the common assumption became that Aristotelian philosophy did in fact require the world to have existed for an unlimited time, partly because creation out of nothing could not be subsumed under any of the Aristotelian modes of change. Change implies the prior existence of something to be the subject of change, and so creation cannot be a species of change. By the 1270s, it was commonly recognized that the concept of creation out of nothing was consistent if not confused with change, but it also became a common conviction that this would wreak havoc on the natural sciences if incorporated among their concepts. The supposed Averroists were thought to have simply denied the temporal beginning of the world (see Eternity of the world, medieval views of).
Double truth: Averroists have been credited with a theory of double truth, occasioned by the fact that when medieval thinkers saw a conflict between philosophy (science) and the teaching of the church, they could not simply reject Church doctrine. Instead, they could hold that philosophers had misinterpreted some of the information obtained by natural means (as Aquinas held, for example), or they could hold that there was no way to detect any error in the derivation of the philosophical thesis, so that the only way out of the impasse consisted in rejecting the thesis on the authority of faith (as did Siger). Alternatively, they could try to explain how the assumption of a first cause makes it reasonable to expect that there are truths which no scientific theory can possibly account for; Boethius of Dacia, who distinguished the conditional truth of a scientific theorem from absolute truth, took that line. A fourth way, asserting that the same proposition can be absolutely true philosophically and also absolutely true theologically, had very few followers, if any at all, but has sometimes been imputed to the 'Averroists'.
To understand how this misconception should arise, one should remember that most philosophers of the thirteenth to sixteenth centuries were masters of arts; it was their job to teach a non-Christian (Aristotelian) philosophy in a Christian society, and so they were caught in the contradiction between reason and faith. Guidelines on how to deal with this dilemma were given in a decision by the Faculty of Arts at Paris in 1272: henceforward, any master dealing with a problem that touched both philosophy and faith was bound by oath to solve it a way that was not contrary to faith. The result was a widespread use of the technique of first providing a philosophical solution and then adding one 'according to the truth of faith'. For some twentieth-century scholars use of this technique has sufficed to stamp a philosopher as an adherent of a theory of double truth.
See also: Aristotelianism, medieval; Boethius of Dacia; Ibn Rushd; Islamic philosophy: transmission into Western Europe; Natural philosophy, medieval §9; Siger of BrabantSTEN EBBESEN