The views of medieval philosophers on the nature of the intellect were framed around the interpretation of Book III of Aristotle’s De anima, especially Chapters 4 and 5, in which Aristotle investigates the nature of the power he calls nous – “mind” or “intellect.” Medieval philosophers were also influenced by Neoplatonic sources such as Plotinus, Proclus, and Porphyry, as well as by the late Greek commentators on Aristotle’s De anima, many of whom read Aristotle’s theories through a Neoplatonic lens.

Aristotle’s method for determining the nature of the intellect and other psychological faculties is to analyze the operations for which the faculty is responsible. Thus Aristotle begins his examination of the nature of intellect in De anima III.4 by noting that, like sense perception, the intellect’s proper operation of thinking is a kind of process that involves a change or alteration on the part of the knower. Aristotle argues that the intellect must therefore be divisible in some way into two parts or aspects – one that is passive and receptive of the change, and another that is active, inasmuch as it produces the change in the patient. Among medieval authors, the former intellect came to be known as the “potential,” “possible,” or “material” intellect, and the latter as the “agent” intellect. Further developing this account of intellection as a process, Aristotle argues that before actually thinking, the intellect is potentially like its object; in the act of thought it is altered in a non-physical way, so as to become actually identified with that object. Thought, then, involves the cognitive assimilation or identification of the knower with the object known – a characteristic that on Aristotle’s view thinking shares with sense perception.

The terms ‘intellectualism’ and ‘voluntarism’ classify theories of moral psychology and of ethics according to whether primary importance is placed on the intellect or the will in human agency. Though classical and early medieval moral theories have a notion of willing as an act of desire (whether rational or not), they lack a concept of the will as a power of the soul distinct from the intellect and from the sense appetite. Only in the later Middle Ages, when the will is thus conceived as a distinct power of the soul, do the classifications of intellectualism and voluntarism properly apply.

Although intellectualism and voluntarism are apt terms for describing the extreme viewpoints, not every writer fits neatly into one of the two main camps, since there are considerable differences among them when it comes to the details of their moral psychology and ethics. An author may, for instance, have both intellectualist and voluntarist tendencies in different respects, or may consider the activities of intellect and will as so intertwined that these classifications become useless.

Historically, this split originated from specific innovative questions which were made a litmus test for a successful defense of human freedom; the fundamental issue was not whether human beings are free, but whether intellect or will is ultimately responsible for their freedom. This chapter focuses on the period in which these discussions among Latin authors were most heated and philosophically most fruitful – namely, from the late 1260s until the early 1300s – a time when ecclesiastical interventions were exacerbating the division.

THE AUGUSTINIAN BACKGROUND

The problem of evil is raised by the combination of certain traditional theistic beliefs and the acknowledgment that there is evil in the world. If, as the major monotheisms claim, there is a perfectly good, omnipotent, omniscient God who creates and governs the world, how can the world such a God created and governs have evil in it? In medieval philosophy in the Latin-speaking West, philosophical discussion of evil is informed by Augustine’s thought. But even those medieval philosophers not in the Latin-speaking world and not schooled in the thought of Augustine in effect share many of his views. For these reasons, it is helpful to begin an overview of medieval responses to the problem of evil with a brief description of Augustine’s position.

Augustine struggled with the question of the metaphysical status of evil; his ultimate conclusion, that evil is a privation of being, was shared by most later medieval philosophers. But ‘privation’ here is a technical term of medieval logic and indicates one particular kind of opposition; its correlative is ‘possession.’ A privation is the absence of some characteristic in a thing that naturally possesses that characteristic. So, on Augustine’s view, evil is not nothing, as he is sometimes believed to have maintained. Rather, it is a lack or deficiency in being in something in which that being is natural. Nothing about this metaphysical position constitutes a solution to the problem of evil; nor did Augustine or any later medieval philosophers suppose it did.

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Aristotelian science conveys understanding by showing the necessary relationship between immediately evident first principles and conclusions about the natural world. To take a trivial example: induction from repeated experience teaches us that all broad-leaved plants are deciduous. We discover that grapevines have broad leaves. We infer that grapevines are deciduous, and thereby we also learn that they lose their leaves in winter because they are broad-leaved (see Aristotle, Post. An. II.16–17).

Aristotelian science explains a subject’s possession of an attribute (the explanandum) by identifying the possession of that attribute with membership in a species, and then citing as explanans the inclusion of that species within a prior genus. In the present example, the property is “losing its leaves in winter,” the species is “grapevines,” and the genus is “broad-leaved plants.” The explanation is then presented in the form of a syllogism. In the first premise an attribute (being deciduous) is predicated of a subject (broad-leaved plant). The second premise introduces a new subject that belongs to the class described by the subject of the first premise, allowing us to conclude that the second subject shares an attribute of the first.

Aristotle describes this demonstration as propter quid science because it explains why grape leaves fall. If the deduction were valid, but its premises were not explanatory, it would count as quia science: knowing a fact without understanding why it obtains (ibid., I.13, 78a22–b3) (see also Chapter 26).

That human beings sometimes act wrongly – be it through ignorance, weakness, or malice (deliberate wrongdoing) – is a commonplace of human experience; that divine grace can help them avoid such wrongdoing is a central feature of Christian doctrine, and thus accepted by all the Christian philosophers whose work is the principal focus of this chapter. These philosophers also accepted that the possibility of weakness – sometimes, but not always, characterized as weakness of will – results from a decisive sin of the first human beings. This “original sin” introduced the kind of disorder into human psychology that is, according to the medieval philosophers, the major component of moral weakness. Grace begins, among other things, the process of reordering this defective psychology. Two very disparate figures inform the presentation of these various issues in the high Middle Ages: Augustine and Aristotle. From Augustine, the medievals derived accounts of original sin, of grace, and – most importantly of all – the beginnings of a theory of consent somehow distinct from both reason and emotion; from Aristotle, they derived an account of moral weakness that they sometimes struggled to integrate with Augustinian teachings on the will, a view of the virtues that informed their account of grace, and a theory of motion that they used to talk about God’s activity in the soul.

WEAKNESS AND WILL

Technically, weakness of will (usually akrasia in Greek, the technical translation of which term in Latin is incontinentia) is exhibited in those cases of action in which an agent acts against what he or she believes to be good. The phenomenon presents a particular problem for those who believe that human action is in principle always rational – a belief that was commonplace in traditions deriving from Socrates, who held that all wrongdoing is explained by ignorance (see Aristotle, Nic. Ethics VII.2, 1145b27–31).

INTRODUCTION

A great many medieval thinkers were involved in the process of censure, either as defendants or as members of an inquiry commission. Often nothing came of the process beyond suspicions or denunciations; other times judicial procedures were initiated; sometimes these led to drastic disciplinary measures. It is very tempting to judge the Middle Ages in light of these practices of information control and to draw the conclusion that freedom of thought was systematically restricted. Another temptation – more subtle – is to reconstruct the history of ideas from these condemnations. Judicial procedures usually entailed a list being made of very short, allegedly erroneous propositions taken from the work of one or more authors: 13 condemned by the bishop of Paris in 1270, and 219 more in 1277; 22 against Peter of John Olivi in 1283; 51 against William of Ockham in 1326, to mention but a few. It is thus very appealing to any historian to cling to these collections of articles in order to reconstruct, by antithesis, an author’s thought, thereby dispensing with the detailed reading of an all too vast body of work. This is one of the reasons why contemporary historiography has focused on the phenomenon of medieval censorship, uncritically adopting the hermeneutical principle that has been widely accepted since Ernest Renan, according to whom “every condemnation in ecclesiastical history rests on a professed error.” Reality, however, is more complex.

When James of Venice translated the Posterior Analytics from Greek into Latin, in the second quarter of the twelfth century, European philosophy got one of the great shocks of its long history. John of Salisbury famously remarked that “it has nearly as many obstacles as it has chapters, if indeed there are not more obstacles than chapters” (Metalogicon IV.6). Latin philosophers had taken themselves to have a grip on Aristotle’s logic, but what they were discovering in the twelfth century was that their grasp extended only to what would be called the Old Logic, the ars vetus, leaving untouched the New Logic of the Topics, the Sophistical Refutations and, most importantly, the Prior and Posterior Analytics.Moreover, as the Latin philosophical canon swelled in the later twelfth century to include not just the full Aristotelian corpus but also the riches of Arabic philosophy, European authors realized just what a central role the Posterior Analytics in particular played in all this work. Although we now tend to focus on the recovery of Aristotle’s natural philosophy, metaphysics, and ethics, it is arguably the Posterior Analytics – not the Ethics, the Metaphysics, the Physics, or the De anima – that had the most pervasive influence on scholastic thought. For it is here that Aristotle sets out the methodological principles that are to be followed in the pursuit of systematic, scientific knowledge: what the Latin tradition would call scientia.

Most medieval thinkers assume that the human soul has several faculties or powers: basic faculties such as digestion or growth, more elaborate faculties such as movement, vision, or imagination, and the characteristically human faculties of will and intellect. This was the mainstream position, but it was not left unquestioned in the later Middle Ages and in early modern philosophy. Several nominalists, for instance, argue that the powers of the soul are nothing but different names for the soul itself, as it is active in different ways. Later, in the seventeenth century, mechanistic philosophers such as René Descartes claim that there is no real distinction between power and act, nor between soul and powers. Descartes reserves the term ‘soul’ for the mind, and so reduces the number of powers drastically; he claims that all lower powers, such as sense perception or imagination, are equivalent either to the mind or certain powers of the body. Even Thomistic authors of the sixteenth and seventeenth centuries, who usually defend the theory of the faculties, at times question the traditional set of faculties and reduce their number. Francisco Suárez, for example, holds that common sense, imagination, estimation, and memory are in fact one power, because all these functions can be attributed to one faculty.

Nevertheless, in spite of the criticisms voiced by nominalist and early modern philosophers, medieval faculty psychology itself was well supported by arguments that have their origin in Greek philosophy. In the Republic, for example, Plato proposes a threefold division of the soul into reason, spirit, and desire. He bases this theory on the fact that there are conflicts in the soul: we may desire an object and at the same time reject it, as when we desire to drink something but reject it because we think it is bad for us.

The Middle Ages inherited from antiquity an approach to metaphysics which supposed both that, to provide an account of being, one provides a theory of categories, and that a division into substance and accident is fundamental to such an account. During the thousand years between Boethius and Descartes, this fundamental division was subjected to careful scrutiny and modified dramatically. Eventually even the term ‘accident’ was partially eclipsed by a competing term, ‘mode,’ which bespoke a competing metaphysical picture; by the mid-seventeenth century Descartes was able to contrast his ontology of substances and modes with an ontology of substances and “real” accidents.

The doctrine of real accidents that Descartes rejects has two medieval roots. One lies in the related theological mysteries of the Eucharist and the Incarnation, and the other lies in the perceived need for real accidents to account for at least some physical phenomena. This chapter explores how these roots formed and developed, how accidents came to be “real,” and how real accidents came to be perceived as a philosophical mistake.

THE CATEGORIES FRAMEWORK

In his Categories chapter 4, Aristotle lists ten heads under which nouns and adjectives fall: Substance, Quality, Quantity, Relative, Place, Time, Situation, Habit, Action and Passion. Although there is little reason to think Aristotle was wedded to this list, it had special salience in the early medieval period, both because the Categories was translated and commented on by Boethius and because the list was also found in “On the Ten Categories” (De decem categoriae), a work attributed to Augustine (but likely from a hand influenced by Themistius).

St. Augustine, bishop of Hippo, was both a theologian of great influence and a philosopher of remarkable originality. He helped shape Christian orthodoxy by identifying the Christian heresies of Pelagianism, Manicheanism, and Donatism, the first two of which have special philosophical interest. Pelagianism, as captured by the maxim philosophers associate with Kant, ‘Ought implies can,’ stakes out a plausible limit on moral responsibility. Augustine’s idea that human beings are obligated to obey the moral law despite the fact that, after the fall of Adam, they have been in a state of depravity in which they can do no good apart from the grace of God, poses a direct challenge to this plausible limit on moral responsibility (see Chapter 29). Augustine also sought to refute Manicheanism, according to which there is a cosmic principle of evil and darkness coeval with the principle of goodness and light. In responding to this attractive way of thinking about the origin of evil in the world, Augustine came up with several responses to the problem of evil, responses that directly influenced medieval discussions of the topic.

In writing no fewer than five detailed commentaries on the creation story in the biblical book of Genesis, Augustine did perhaps as much as any philosopher has done to try to make sense of the idea that God created the world out of nothing. Indeed, in the thirteenth-century debate on whether the world is eternal Augustine’s view of ex nihilo creation became the antipode to the Aristotelian view that the world had no beginning (see Chapter 17).

The psychological ruminations of Plato and Aristotle gave rise to two interpretative streams that together shaped the course of later medieval theories of perception. The most important of these was the Arabic tradition, which profoundly influenced scholastic thought. Less significant, but still influential, were early Latin accounts of perception. Out of this legacy, scholastic Latin authors developed rich and varied accounts of the physiological and psychological mechanisms of perception.

THE GRECO-LATIN INTERPRETIVE STREAM

Early Latin accounts of classical Greek theories of perception were channeled through such encyclopedic thinkers as Pliny, Macrobius, and Martianus Capella, as well as Augustine and Boethius. Perhaps the most important among these channeling agents was Calcidius, whose fourth-century Latin translation of the first half of Plato’s Timaeus – complete with commentary – proved enormously influential on the study of natural philosophy from the late Carolingian period to at least the mid-twelfth century.

Hugh of St. Victor’s Didascalicon offers a good example of how this interpretive stream had developed by the early twelfth century to combine elements from Plato’s account of perception with second-hand knowledge of Aristotle’s theory. Hugh follows Aristotle’s threefold division of the soul according to its fundamental capacities, beginning with nutrition, passing through sensation, and culminating with reason in humankind (I.3). The link between sense and reason, Hugh explains, is the imagination, which “is sensuous memory made up of the traces of corporeal objects inhering in the mind” (II.5, tr. Taylor, p. 66).

Ancient philosophers had a well-equipped repertory of descriptions for human activity, but it was only after Augustine that thinkers, especially in the Latin West, adopted an explicit concept of the will. This allowed them, for better or for worse, to set out a good portion of their philosophical psychology in terms of the interaction of intellect and will (see Chapter 30). Toward the end of the eleventh century, Anselm proposed a distinction within the will between an “inclination for justice” and an “inclination for benefit.” An agent’s “every merit, whether good or evil,” he says, derives from one of these two basic inclinations (De concordia III.12). Two centuries later, citing Anselm, John Duns Scotus adopts the labels but, as we shall see, develops a significantly distinctive account. Pairings of this general sort can be found in ancient philosophy (and will be discussed briefly below), but the developed idea of dual basic inclinations of the will is probably unique to Anselm and Scotus. But while explicit appeal to inclinations of the will is thus rare, the issues raised here by Anselm and Scotus are central even nowadays in the analysis of moral psychology (as in debates about the nature of the moral object or the status of free will) as well as in moral theology (on sin and grace).

ANSELM

Justice is a central concept in Anselm’s moral theory, and it appears in all his writings. In several works – De casu diaboli (The Fall of the Devil) and De concordia – he considers justice in the context of the two basic inclinations of the will. In an earlier dialogue, De veritate, he takes up directly the more fundamental question with which we should begin, the question of what justice is.