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John Wyclif$

Stephen Edmund Lahey

Print publication date: 2009

Print ISBN-13: 9780195183313

Published to Oxford Scholarship Online: January 2009

DOI: 10.1093/acprof:oso/9780195183313.001.0001

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John Wyclif

Stephen E. Lahey (Contributor Webpage)

Oxford University Press

Abstract and Keywords

Wyclif’s philosophical thought followed a period of remarkable innovation in the history of medieval philosophy, when the Ockhamist movement challenged the Aristotelian synthesis of Thomist and Scotist theologians. From the 1320s, Oxford thinkers like Thomas Bradwardine and the Mertonian Calculators had developed a rigorous logical method of analysis for the exploration of semantics and Aristotelian physics. Their analytic approach, in part inspired by Ockham’s logic, characterized Oxford philosophy and theology well into the 1370s. This chapter explores the relation of Wyclif’s epistemology, with attention to his fondness for analogy to the science of optics, to his understanding of the nature of science in the context of his predecessors in Oxford’s “Golden Age of Theology.” Foremost among these predecessors are Adam Wodeham, William Crathorn, Robert Holcot, and Richard Fitzralph.

Keywords:   Mertonian Calculators, Ockham, epistemology, certainty, logic, optics, Wodeham, Holcot, Crathorn, Fitzralph

In late August 1909, Charles Doolittle Walcott was prospecting for fossils on the Burgess ridge in what is now Yoho National Park, in the Canadian Rockies of British Columbia. He found a section of rock embedded in the mountainside that contained the richest and strangest collection of fossils ever discovered, which today we call the Burgess shale. Walcott struggled to classify these tiny animals from the Middle Cambrian period, 530 million years ago, because they just didn’t fit the expectations of early twentieth-century paleontology. So he described them as he felt they should have been, interpreting the fossil evidence to fit into the accepted scientific expectations of what lived in the warm sea beds of the early Paleozoic era. In the 1970s, when paleontologists at Cambridge recognized Walcott’s error, they began to explore the fascinating possibilities of almost twenty unknown phyla. Today, there are some thirty-two distinct phyla in the animal kingdom; the Burgess shale shows us almost twenty directions that evolution could have taken, but didn’t, thus giving paleontologists and evolutionary biologists a tremendous opportunity to explore possibilities that would otherwise never have been imagined.

Our understanding of the period in which Wyclif developed as a theologian has changed in the same way that our understanding of the Burgess shale has changed. What looked like a degenerate, inbred version of high medieval theology to scholars as recently as the mid-twentieth century now (p.33) seems a century rich in innovation, particularly important for understanding the theological arguments that raged during the Reformation and the philosophical and scientific ideas of early modernity. This is thanks to scholars committed to state-of-the-art editions of texts, to historians of thought tracing the development of ideas, and to philosophers who have been influenced by the analytic approach of the twentieth century. What appeared to one editor at the Wyclif Society as philosophy of “a spuriously technical type . . . [lacking] the true philosophical spirit which, in spite of its over-refinement, impresses one with admiration in Duns Scotus” has since come to be recognized as evocative of the interests and methodology of philosophers today.1

To understand the positions that Wyclif adopted during his years at Oxford, from the early 1350s through the 1370s, a familiarity with the issues that were in the forefront of intellectual debate at the time is necessary. It was understandable for scholars a century ago to have seen Wyclif as a proto-Reformer emerging from the sterile debate of the schools, imbued with a vision of the needs the church would face in the coming centuries. Given the conviction that theologians spent their days parsing logical phrases and splitting ontological hairs, what else but a vision of the Reformation to come could explain the volumes demanding ecclesiastical reform, a rebirth of scriptural hermeneutics, criticism of the sacraments, and indictment of the friars that came from the evangelical doctor’s pen? But much of what Wyclif would later write had already been debated in the early decades of the fourteenth century, and in many instances, his seemingly forward-looking ideas had been in the works at the Oxford schools for years before he was born.

Theology in the thirteenth century was characterized by grand, all-encompassing systematizing, but in the fourteenth century, it evolved into a more epistemologically oriented project, preoccupied with questions as to the possibility of understanding theology to be a science. The most important figure in this evolution was William Ockham (1287–1347), whose logical and linguistic investigations catalyzed a new approach, both at Paris and Oxford.2 Indeed, the period beginning with Ockham’s presence at Oxford and extending to 1349, when the plague hit England, has been described as a golden age of theology for the university. Ockham was born in Surrey and was probably in London before 1300. He began formal theological training in 1310, and given the general requirement of seven years’ training in the trivium and quadrivium of the arts curriculum prior to the study of (p.34) theology, he was likely studying at Oxford by 1304. At that point, Henry Harclay, a secular trained in Paris, was chancellor of the university. Harclay and Richard Campsall, who was affiliated with Merton College, were Oxford’s most eminent figures at the time, and both were skeptical of the Scotist approach then dominant at Paris. Campsall in particular was interested in the use of terminist analysis, the increasingly influential logico-semantical approach, for ferreting out the metaphysical phantoms that clouded theological problems. During his period in Oxford, Ockham wrote the influential Summa Logicae, an exposition of the relation of things to words and concepts, which embodied his philosophical approach. He also wrote commentaries on Aristotle’s logic, works on physics, and a treatise on future contingents grounded in Aristotle’s On Interpretation. In addition, his quodlibetal disputations, Sentences commentaries, and treatises on the Eucharist also date from this period.

His innovations led to questions both within his provincial chapter of friars and at Avignon, and Ockham departed for the Franciscan convent at the papal see in 1324. There, he met Michael of Cesena and other influential continental Franciscans, and in the midst of increasingly hostile criticism of his thought, he fled to Munich with his like-minded fellows on 26 May 1328. His flight was not from cowardice, but from a conviction that the pope, John XXII, was incapable of objectivity. Ockham had identified himself with the Franciscans committed to St. Francis’s ideal of apostolic poverty, and John had famously condemned their theological arguments against the legitimacy of property ownership in 1323. This papal condemnation put a formal end to the “poverty controversy,” to be discussed in chapter 7. Ockham’s arguments for the “spiritual” Franciscans date from this period in Germany, and include detailed examination of lordship, the ownership and use of property, legal and natural rights, and the authority of the papacy both within the church and in the secular realm.

Ockham’s metaphysics and epistemology did not have a causal philosophical bearing on these latter works, but Ockham (or more likely, someone close to him) explains in Tractatus de Principiis Theologiae that his overall approach is based on two fundamental principles, namely, the principle of parsimony and the principle of absolute divine power. The former, known popularly as “Ockham’s razor” is usually formulated “plurality is never to be posited without necessity,” or “it is foolish to do with more what can be done with fewer,” an Aristotelian maxim well known throughout the medieval period. Ockham’s philosophical approach involved using the principle (p.35) to avoid positing metaphysical entities beyond what was absolutely necessary. The classic example of this is with the ten Aristotelian predicables. In Categories, Aristotle lists ten things that can be said of an object: substance, quality, quantity, relation, place, time, position, state, action, and passion. Ockham argued that philosophers were too quick to allow abstract reasoning about these categories to lead to supposing that there were such things as relations or points in time or space existing apart from related things. His position was to restrict the number of kinds of things to two: substances and qualities. Everything else, including relations, places, times, motions, instants, are not real beings, but the products of our thinking and speaking about the world. Why did Ockham allow qualities to remain? Most of his contemporaries believed that the doctrine of transubstantiation, the theological account of what takes place at Eucharist, lies at the heart of Ockham’s belief that qualities are real beings, as we will discuss in chapter 4 on Wyclif’s eucharistic theology.

The principle that “God can produce anything the production of which does not involve a contradiction” is a succinct statement of God’s absolute power. In discussing God’s omnipotence, theologians since Peter Damian (d. 1072) had found it useful to distinguish between what God in fact wills and does in creation, and what God could do, all things being equal. That is, God has ordained that creation proceed according to fundamental laws, and what God wills and does within creation is in accord with those laws. But God could have willed that different laws be in effect, or that fewer laws apply, or more, which would have made for a different structure to creation. In 1290, the conflict between the mendicant orders and papal authority involved Nicholas IV moving to rescind the privileges granted to the friars in Ad fructus uberes (1281) by his predecessor, Martin IV. Nicholas relied on Henry of Ghent, who saw potentia absoluta as involving change in the created structure laid out according to potentia ordinata, allowing mutability in divine law. Henry argued that popes could conceivably change rulings of their predecessors on the strength of papal power’s analogy to divine power, but was loath to admit that God would actually make such changes. By the end of the thirteenth century, the distinction had come to suggest the possibility of God altering the created order of things. Further complicating matters, Scotus continued to use it in the traditional manner, despite having acknowledged this mutation in the distinction’s applicability.3 This opened the door to his followers’ using the distinction to generate possible divine courses of action within creation outside the purview of potentia ordinata. (p.36) In 1315, regent masters of theology at Oxford condemned several theologians for making use of the distinction in generating counterfactuals. While not condemning use of the distinction, this effectively limited the scope of possible scenarios that theologians might generate.

The distinction figured again in 1324–1328, during the Avignon commission’s investigation and ultimate condemnation of Ockham. Included among the positions condemned were some that Ockham had adopted from Scotus on the possibility of God, through potentia absoluta, being able to accept someone lacking the created habit of grace among those predestined for salvation. Ockham’s argument in Quodlibet VI.1 was a response to those who conceived of the two kinds of divine power as license to speculate about God doing things in creation that might depart from the divinely ordained plan. The distinction should not be understood to mean “that God is able to do certain things ordinately and certain things absolutely and not ordinately, for God cannot do anything inordinately.”4 Here, Ockham argued that, by potentia absoluta, God could conceivably save an unbaptized person, but that he would not do it against his will. John XXII, Ockham’s papal nemesis, argued that the distinction was theologically useless, holding that since God’s eternal knowledge is immutable, and since all things can only happen as God knows them, then all things must happen of necessity. Since scriptures are unequivocal about baptism now being necessary for salvation, nobody can possibly argue that God would ever countenance the unbaptized being saved, through whatever kind of trumped-up distinction in the divine power one might cook up. Ockham angrily responded from Munich, in his Opus Nonaginta Dierum, that the pope completely missed the point of the distinction, denying all freedom, divine and human; this was the sort of nonsense one might expect from heretics, laymen, and old women.5 It would be easy to dismiss this as political bickering under the guise of theological controversy, but the argument set the stage for much that would comprise fourteenth-century Oxford’s debates, particularly about the relation of theology to the other sciences.

But before we survey Oxford’s theological golden age, it is important to bear in mind that the theological positions that evolved over the next three decades were not simply members of one camp championing their founder’s position against the paladins of another theologian’s school. It would be very convenient if the Dominicans were uniformly Thomists, the Franciscans were either Scotist or Ockhamist, the Augustinians disciples of Giles of Rome, and the seculars generally adherents of the approach of (p.37) Grosseteste. But this was not the case; among Ockham’s most active opponents at Oxford was Walter Chatton (d. 1343), a fellow Franciscan, while Henry Harclay, Oxford’s chancellor during the latter part of Ockham’s stay there, whose ontology was quite similar to Ockham’s, was a secular. Despite the great impact that Scotus had in Paris, Scotism at Oxford was a paltry thing, and Thomism was not the authoritative approach among Oxford Dominicans that it might have been. The emphasis on science and logic that characterized Oxford thought led away from broad, all-encompassing metaphysical approaches and tended to foster a more individualistic, analytic brand of theology than the phrase “school of thought” might allow.

Adam Wodeham (d. 1358), Ockham’s student and friend, attacked the arguments of his fellow Franciscan Walter Chatton with notable vigor. Chatton had argued, as Wyclif would, that a return to the safety of theological tradition and scriptural foundation would best serve the needs of the day.6 Wodeham argued against using natural reasoning to broaden our understanding of the divine, rejecting Chatton’s attempts at natural theology to emphasize this impossibility. While one scientific conclusion may seem applicable in another field, it would be foolhardy to assume that this holds across all science. We may presume that two diverse lines of argument lead to the same conclusion, as in the famous five ways that Aquinas uses to demonstrate God’s existence, but “diverse sciences do not prove formally the same conclusion through the same medium, unless by mendacity.”7 Scientific reasoning’s ability, for example, to construct arguments demonstrating the existence of an infinite being may entice one to suppose that it can demonstrate God’s existence, but the God it constructs is ultimately nothing in comparison to the God of theology. There is no possibility of reason establishing the falsity of the apparently valid syllogism “this thing is the Father; this same thing is the Son; therefore the Father is the same as the Son,” for by Aristotle’s rules, the conclusion follows neatly from the premises. “And thus unless through our faith it were known that one thing is three things, we would believe firmly the aforesaid sophism to have been well argued.”8

Bradwardine and the Calculators

Further emphasizing the problems that come with trying to fit these theologians into neatly defined groups is the thought of the calculators, a group of (p.38) secular scholars at Oxford’s Merton College. Like Ockham and his followers, the calculators were philosophers with a keen interest in logical disputation and the complexities of mathematics and theoretical physics to which they could lead. Being a calculator was certainly not the same as being an Ockhamist. One of the foremost calculators, Thomas Bradwardine, vigorously opposed Ockhamist theology. Disputations de sophismatibus were the standard genre of argument in which undergraduate students learned to engage one another in intellectual dispute in medieval universities. The students used ambiguously worded sentences like “Socrates twice sees every man besides Plato” to analyze how terms functioned within propositions. In most cases, the analysis focused on syncategorematic terms, which lack independent signification outside of their use in sentences. In the example, the term “besides” has an ambiguous reference, and resolving the ambiguity would involve addressing the larger question of how exceptive terms function in the distribution of meaning within a proposition. While, at first sight, sophismata may appear to be a recondite academic exercise, the purpose of the genre was to sensitize students to the relation of language use and reasoning by exploring the problems that come from assuming things about meaning that have not been established. As is the case now with courses in logic or programming, formulating texts whereby the rules for this level of analysis could be established was a very specialized affair, and the logicians at Merton College were tasked with this responsibility.

Merton College had been founded in 1264 and was reserved for those studying for higher degrees. Both Scotus and Ockham had studied there, and many of the foremost figures in fourteenth-century Oxford were associated with the college. Here, a movement arose among the logical theorists intent on regulating sophismata in which physics and theoretical mathematics began to figure importantly. Take a proposition like “Socrates is whiter than Plato begins to be white.” This sophisma, the first in Richard Kilvington’s collection from the 1320s, tests the extent to which we can understand a degree of a quality, whiteness, and its ratio to a lesser degree of whiteness.9 Kilvington’s sentences, with their problems involving degrees of quantity or quality, or traversing distances, find their resolution in logical analyses of the terms, but as the genre developed, mathematical and physical speculation became increasingly complex. Walter Burley, a Mertonian from 1305 to 1309, had investigated the physics of a substance beginning to be and ceasing nonexistence in his quodlibetal question De primo et ultimo instanti, and he introduced analyses of problems of natural philosophy into the (p.39) genre. Bradwardine’s interest was in the mathematics of ratios and how it applied to theoretical understanding of force, resistance, and velocity, and his De Proportionibus (1328) would revolutionize the physics of motion.

Thomas Bradwardine (c. 1300–1349) began his career as a theologian and natural philosopher at Merton College in the 1320s, and had entered the service of Edward III in 1339 as royal chaplain. In the king’s service, Bradwardine was witness to the battle of Crécy in 1346, served as a negotiator for peace with France, and delivered a famous sermon on the occasion of victory over the Scots at Neville’s Cross. He was elected archbishop of Canterbury in August 1348, but because the election had bypassed Edward’s permission, he had to stand aside and allow John Ufford to occupy the See at Canterbury. When Ufford died later that year, Bradwardine was elected again, and Edward appears to have allowed his chaplain to become archbishop in July 1349. The Black Death had been devastating English society for several months, and it claimed Bradwardine only thirty-eight days after his accession. Despite the fact that he likely had left Oxford toward the end of the 1330s, the effects of his presence were felt well into the 1360s and ’70s, when Wyclif was active. Not only had he been foremost among the calculators of Merton College, but he had formulated a theological response to Ockhamism during the 1340s that was influential into the sixteenth century. Historians of science remember him for advances in kinematics and mathematical theory, while students of the Reformation turn to his De Causa Dei contra Pelagium to understand the debates that raged in the universities when Luther and Melancthon studied. Each of these venues figure importantly in Wyclif’s writings, in which Bradwardine—alone among all the figures of Oxford’s golden age—is frequently mentioned with respect and reverence.

“Mathematics,” Bradwardine wrote, “is the revelatrix of truth, has brought to life every hidden secret, and carries the key to all subtle letters.” An example of Bradwardine’s mathematical thought can be found in his assessment of how to explain the relation of variation in the velocities of a moving thing to variation in the forces and resistances that affect velocity. The traditional understanding in Aristotelian physics relied on the axiom that motion occurs only when the motive force is greater than the resistance offered, so that velocity is explained as proportionate to the ratio of force to resistance. Bradwardine reasoned that, if we begin with a rate of motion in which the force is greater than the resistance, and if we continually double the rate of resistance while holding the rate of force constant, (p.40) at some point the rate of resistance will be greater than the rate of force. The problem lies in the axiom of velocity being proportionate to the ratio of force to resistance; as the rate of velocity decreases in proportion to the increase of resistance, there will still be a rate of velocity assignable at the point that resistance is greater than force. This would mean that there is a measurable, albeit tiny, rate of velocity assignable to a stationary object. Better, Bradwardine argued, to recognize that velocities vary arithmetically, while the ratios of force to resistance vary geometrically.10

In the two decades that followed, the calculator tradition at Oxford would flourish. Foremost among the calculators was William Heytesbury, who would become chancellor of the university in 1370. Heytesbury’s interest was in infinite divisibility and the nature of continua, and he was a pioneer in analyzing the logic of quantitative statements about heat and color. His Regulae Solvendi Sophismata, one of the textbooks for undergraduates that was the initial aim of the calculators, illustrates the reciprocity of logic and mathematical physics that characterized the movement. In it, problems of physics and mathematics are examined as logical constructs, with the application of physical and mathematical principles mixed into the semantical analysis. Another important figure, Richard Swineshead (pronounced Swinnis-et), elevated the abstraction in the mathematical analysis of physical propositions to new levels of intricacy. His Liber calculationum considers how to parse propositions concerning the measurement of the intensity or absence of qualities. Does one understand a quality’s intensity by proximity to the highest degree of a quality, or by distance from the absolute absence of the quality? Further, is it possible to analyze the distribution of intensities of a quality across a given substance? What of the intensity of light? And building on Bradwardine’s understanding of motion, if we consider an object falling through the center of the earth, does the part of the object that has already passed the center resist the descent of the parts that have yet to reach the center? The practical, physical applicability of these questions is beside the point. Swineshead, like all of the calculators, was more interested in the complexity of mathematical analysis that the logically formulable problems demand.11 Leibniz would later praise Swineshead as the individual who introduced mathematics into philosophy, and Robert Burton, author of the encyclopedic Anatomy of Melancholy, described him as exceeding the bounds of human genius, but later humanists would generally reject the calculator tradition as typifying the subtleties that had complicated scholasticism to the point of irrelevance. From the standpoint of (p.41) the history of science, the Oxford calculators introduced mathematics into speculations about problems in physics, illustrating the need for advanced mathematical operations, but their interest was primarily in using science as a heuristic device for logical analysis. For the purposes of our survey of fourteenth-century Oxford, though, this calculator tradition shows the level of the analytic nature of philosophical discourse in Wyclif’s day.

Skepticism and Certitude

The meticulous logical analysis of propositions was not, despite appearances, an end in itself. The calculators were motivated by a strong desire to unravel theological problems that had long plagued Christian thinkers, a prime example of which was the problem of predestination and human freedom. Bradwardine’s De Causa Dei contra Pelagium is the most important fourteenth-century articulation of a traditional, Augustinian approach to this problem. Ockham had formulated a position that Bradwardine thought to be suspiciously evocative of Pelagianism. This position, first articulated by Pelagius in the fourth century, entails a radical voluntarism, in which God’s causal power has no purchase on human willing. In effect, Pelagius’s position allowed human beings to merit salvation through their own good works, without God’s cooperation through grace. We will discuss Bradwardine’s association with the circle of Bishop Richard de Bury of Durham in chapter 3; it was during these years that he composed De Causa Dei, a work that was to have a significant impact on Wyclif’s understanding of divine knowledge and of the nature of the church. Because tracing out Bradwardine’s argument would take us too far astray from the topic of theology and epistemology, we will save that for chapter 6, on Wyclif’s ecclesiology.

If the reaction to Ockham at Oxford had just been an old-fashioned Augustinian hostility toward Pelagianism, we could classify this as a largely in-house theological debate and move on. But there was more at stake than the right approach to the hoary problem of God’s foreknowledge and human freedom. The arguments consequent on Ockham’s approach suggested that theology might not fit the standard of scientific reasoning. Given the possibility of God causing our perception of nonexistent entities, it was even plausible that all human knowledge might be, at best, only probable. If it is possible that God can cause us to perceive things that are not present, (p.42) or to believe things to be true that are not true, then all that seems evident to human reason runs the risk of being dubitable. When discussing the history of skepticism in Western thought, the usual course is to proceed from the academics of ancient Greece and Rome to the use of systematic doubt as the basis for modern thought in Descartes’ Meditations, on the assumption that Christian dogmatism forbade its use in scholastic thought, or that Aristotelian thought provided sufficient material to stave off skeptical tendencies. The great figures in skepticism include Pyrrho, Carneades, and Sextus Empiricus in antiquity, and Descartes, Bayle, and Hume in early modernity. Augustine had rejected skepticism as a useful philosophical method in Contra Academicos (386 CE) and had argued in De Utiliate Credendi (392 CE) that, since few men were sufficiently wise as to understand the truth, it is better to believe and avoid sin than to doubt and risk damnation. And until the fourteenth century, skepticism had a bad reputation; to accuse one’s opponent of having a position that led to skepticism, as Scotus did to Henry of Ghent, was as good as rendering it untenable.12 Etienne Gilson set the terms for twentieth-century consideration of skepticism in scholastic thought by identifying it with Ockhamism, describing Ockham’s thought as an apprentice sorcerer unleashing forces that would overturn the classical scholasticism of the thirteenth century. Because Ockham was ontologically a “nominalist,” it became the norm to equate Ockham’s ontological approach with a skeptical distrust of natural theology and a correspondent fideism.13 But the reality of later medieval skepticism is much more complex. Not every fourteenth-century theologian with a healthy respect for the limits of human reasoning was a skeptic. Still, burgeoning interest in the absolute power of God and its relation to human knowledge, an important aspect of Ockham’s thought, led many to explore the philosophical uses of epistemic skepticism.

For centuries, scholastic thinkers had Aristotelian reasoning as their firm foundation, and by the end of the thirteenth century, theologians had used syllogistic reasoning to articulate ideas of great subtlety about the divine nature. In his Summa Logica III, 16, Ockham argued that great care should be taken with the terms in an expository syllogism, the building block of scholastic reasoning. It could not have as its subject a term that is ambiguous in number. For instance, “homo est Socrates, homo est Plato, ergo Socrates est Plato” may be true, and it may be false, depending on how the term “man” refers. If the term stands for a singular thing, a man, then the syllogism would prove that Socrates and Plato are two names for (p.43) the same person. This is either the truth, or it is not. If the term stands for a plural, then the conclusion would be impossible if Socrates and Plato are two different people. So the ambiguity of the term “man” means that the syllogism doesn’t really tell us anything. The subject of a syllogism must be either recognizably singular or recognizably plural to prevent the syllogism from being useless. The problem for theology arises in discussing God’s triune nature. “This essence is the Father, this essence is the Son, therefore the Son is the Father” is useless as an expository syllogism because of the ambiguity of the term “essence” when describing God. Does it refer to one thing or to more than one? If essence describes one thing, then the syllogism is saying something about the identity of the persons of the Son and the Father within the essence. If it describes several things, then its meaning is confusing: do the different persons themselves have essences? Or is the syllogism just falsely conceived, since the faith holds that there can only be one essence and several persons? The syllogism is not wrong in itself; in Quodlibet III, q.3, Ockham explains that if we could enjoy the vision that those in heaven have of God, the ambiguity of the term would vanish and the syllogism would clearly and unequivocally describe the reality we perceive. But the unbeliever, for whom the term “God” refers to a fictional entity, will not recognize the truth of any syllogism in which there is reasoning about the divine nature as something real. Ought we then to conclude that philosophy is of no help whatever to theology? In Quodlibet V, q.1, Ockham explains that delineating the way that terms in statements refer, whereby he has established that a theological truth cannot be proven scientifically, is itself a philosophical activity. Hence, philosophy is of tremendous utility for the theological project. The result of this general line of reasoning, though, is that theology is distinct from other sciences, and philosophy, theology’s erstwhile handmaiden, becomes the de facto queen of the sciences.

Peter Aureol (1280–1322), a contemporary of Ockham’s in Paris, had warned strenuously against assuming that “whatever appears, exists” in his analysis of human cognition, indicating that the appearances of things perceived serve as the basis for our knowledge of things in the world. In the next generation of Parisian theologians, Nicholas of Autrecourt (c. 1295–1369) stunned his colleagues by arguing that, aside from the certainties of faith, all that we have to rely on in our reasoning is the principle of noncontradiction. This means that basic principles of cause and effect, and metaphysical fundamentals like “accidents require substances for their existence” are ruled (p.44) out as the bases for knowledge, because doubting them does not entail a contradiction. While we may never have experienced an accident without a substance, or smoke without fire, it would not involve a contradiction of terms to imagine them, in the way that one imagines a square circle or a married bachelor. This seriously endangers the certainties of science, broadly understood to include all descriptions about the world around us. Nicholas was famously censured at Avignon in 1346. Although his skeptical tendencies do not amount to classical skepticism, they are indicative of a tendency toward skeptical reasoning in fourteenth-century theology that was quite active in Oxford.14

Some Oxford theologians were willing to question the tenets of causality to test the extent to which we are capable of certain empirical knowledge, even if only to sharpen their students’ wits. One, a Benedictine known only as Monachus Niger, or the Black Monk, who wrote between 1337 and 1341, suggested that we cannot know substances by natural knowledge:

[B]ecause then it could be known in the Sacrament of the Altar [i.e., the Eucharist] when it would be bread there, and when not. From this it follows that it is not pure philosophy to hold a substance to exist in the nature of things. I prove this because nothing holds naturally unless the knowing of it naturally comes, and the knowledge of substance cannot come naturally, as demonstrated with the Sacrament of the Altar . . . so there can be no experience had of a substance.

We seem to have knowledge of a substance underlying accidents, because something remains underneath even as the accidents change. Just because something seems to remain constant as a ball of wax melts from a solid lump to a liquid mass, it does not follow that there is something underneath.15

Richard Fitzralph was another prominent member of Richard de Bury’s Durham circle, and we will describe the relation of his thought to Wyclif’s in our discussion of dominium in chapter 7. Later in his career, he would become the archbishop of Armagh, earning the nickname “Armachanus,” and proved to be an influential figure at Avignon during negotiations with the Orthodox church in the late 1330s and early 1340s. His Summa de Quaestionibus Armenorum, a dialogue in nineteen books outlining papal primacy in the face of Greek and Armenian theological objections, is a storehouse of classical arguments for papal authority and was used extensively in Reformation and Counter-Reformation debates. Included in this work (p.45) is an autobiographical prayer, from which we can get a sense of his feelings about his time at Oxford:

Before, I supposed myself profound through Aristotelian dogmas and argumentation with men of limitless shallowness, when You touched me at my core with Your heavenly truth, dazzling me with Your scripture, scattering the clouds of my error, showing me how I was croaking with the frogs and toads in the swamps.16

One manuscript of Fitzralph’s Sentences commentary contains a question in which the author argues that one cannot know whether there is any material substance aside from oneself. The sensations experienced of one’s own body are not sufficient for knowing the body, though; we need some sort of dialectical argument to establish that we have a body, which would provide the certainty that we cannot attain with sense experience alone. Does this make him a skeptic? Fitzralph knew that Henry of Ghent had answered a similar question by advocating an epistemology reliant upon divine illumination, in keeping with traditional Augustinian thought. In his De Magistro, Augustine had argued that we attain understanding of any truth only through God’s illumination of our minds: “Regarding each of the things we understand, however, we don’t consult a speaker who makes sounds outside of us, but the Truth that presides within over the mind itself.”17 If God provides human understanding of truth, then this argument would only show that, without divine illumination, we are helpless. Aquinas, Scotus, and Ockham rejected illumination theory, but it was by no means lacking proponents in fourteenth-century Oxford; Wyclif would be an advocate. Fitzralph devotes considerable attention to epistemology in his Sentences commentary, distinguishing between what is present to our understanding as a result of perception and what the act of understanding what is present involves. Further, he continued throughout his academic career to revise his thoughts on the unity of the soul and on the issue of how correctly to delineate the process of understanding, complicating any attempt to categorize Fitzralph’s epistemic program. Gordon Leff argues that Fitzralph was a proponent of illumination theory, but more work needs to be done before we can understand the place of this question in his overall epistemology.18

A somewhat later figure, also suggesting the skeptical approach of Nicholas of Autrecourt, instead uses the uncertainty of human knowledge to underscore a determinism suggestive of Bradwardine. Nicholas Aston, (p.46) a post–Black Death theologian slightly older than Wyclif, was chancellor of Oxford from 1359 to 1361. He argued that only God is necessary; the past is contingent, as is the present, and God can make it to have been different, although he does not. Any truth we have about created being might easily dissolve into falsehood without our understanding the reason. This does not mean that the created order is so fluid as to bring about that change. God is necessarily perfect and is reliable as the necessary foundation for created order. The problem lies in our understanding, which is based in dubitable sense perception and is thus possibly illusory. Even something as apparently certain as “nothing can be in two places at the same time” is up for questioning: “God can make it that the same man would be in different places, [and] a man could meet himself and not know that it was him, and cut off his [own] head without knowing.”19 Causality is likewise open to doubt, because if some particular effect has to follow from some cause, as our thinking suggests, then God’s being would not be the only necessary thing in creation. Likewise, logical inference is jeopardized, because a given conclusion need not follow from premises that appear necessarily to lead to it.

Interestingly, Aston’s extreme position is more in keeping with Bradwardine than with Ockham or others. First, Aston believes that only God’s being is necessary and that propositionally structured truth exists independently of the sentences we construct. While our understanding of causality, and hence of the causal order, is so imperfect as to be incapable of demonstrating God’s existence in the way that Aquinas or Scotus suggested, it is still possible to use logic to show the necessity of God’s being. Aston notes that his opponents, the moderni, hold that the statement “God does not exist” is not formally contradictory, despite the fact that all created being is contingent on God’s existence. Consider a proposition and the state of affairs it describes. If the state of affairs changes, so does the truth value of the proposition. But if the proposition contains a contradiction, it is always false, even if the proposition also accurately describes the state of affairs. If God exists, then a proposition p asserting that God does not exist would contain a contradiction, namely, that a necessary being does not exist. It’s being made false by God’s existence would not be the cause of its inherent falsity; that it contains a contradiction is the cause of its inherent falsity. Now, Aston continues, if God’s existence were contingent, like the moderns say it is, then it could begin to be and cease to be. The proposition would still contain a contradiction, though, so it cannot be that a necessary (p.47) being does not exist. This is what Aston calls his “Achilles argument,” and it is obviously based on an assumed real relation holding between true statements and things. A skeptic holding that true statements only accidentally reflect reality would never agree to this variation on Anselm’s famous argument from Proslogion 2–4, and a follower of Ockham, for whom the reference of terms within propositions is dependent upon the concepts we derive from what we perceive, would reject Aston’s semantic realism. Further, since God is the only necessary being, any true answer to the question “why is this the way things are?” must find its basis in God’s being. This includes every case of human willing, whether good or evil, although Aston shies away from what he sees as an excessive determinism in Bradwardine. Because his approach is semantically oriented, grounded in a propositional realism in which true statements are made true by their correspondence to a propositionally structured truth in God’s being, it would be a mistake to call Aston a skeptic. It is difficult to avoid the powerful skeptical overtones in his description of the contingency of human understanding, though.

The case is similar for Robert Holcot (d. 1349), whose arguments are easily interpreted as skeptical but are better understood in their theological context. Holcot was a Dominican known both for his incisive logical mind and his remarkable gifts as a preacher. He was active at Oxford from 1330, but by 1337 may have left to join Richard de Bury in Durham, where we will see him in our discussion of the de Bury circle in chapter 3, on Wyclif’s realism. By 1342, he was active as a pastor in Salisbury, and later in Northampton, where he died of plague. He was best known during the centuries after his death for his remarkable Commentary on Wisdom, an encyclopedic scripture commentary on the apocryphal Book of Wisdom, which contains pastoral advice about the path of one’s life, just political rule, married life, and many social issues. At present, this fascinating work is all but forgotten; those few familiar with his thought today recognize him as an important, original response to Ockham. In his Sentences commentary, Holcot addressed the incompatibility of Aristotelian logic and the nature of the Trinity typified by this syllogism: “the divine essence is the Father, the divine essence is the Son, therefore the Father is the Son,” the premises of which are true, which lead to a valid but false conclusion. While earlier theologians had addressed this by qualifying how the divine essence “is” the person, Holcot denied the validity of using a distinction to avoid the doctrinally problematic conclusion. This led him to decide that the demands of the faith so contrasted with the rules of logic that there must be two systems (p.48) of logic: the Aristotelian one, applicable to the natural order of creation, and a higher logic in which supernatural truths are comprehensible.

It is likely that Wyclif formulated his own position on the relation of faith to reasoning in response to Holcot, who held that what is evident as scientific knowledge is born from demonstrative arguments; no faith is involved in the process. Theology could only be considered a science if it conformed to one of the three senses in which the term scientia is understood. In the broadest sense, it is firm adherence to the truth, and in this sense theology is a science. But what is the basis for this adherence? If the assent is based in evident knowledge of empirical data, or in necessary first principles, then one cannot include theology among the sciences, for no viator can claim either empirical knowledge or intuitive comprehension of supernatural truths as necessary first principles.20 Holcot would change his position somewhat in his Quodlibeta, where he agrees with Ockham about the ambiguity in the reference of terms about God impeding syllogistic function. One simply cannot form syllogisms about God that suggest that we are reasoning about him. This allows Aristotelian logic to remain universal, because its principles do not include reasoning about such a being as God. Thus, truths of faith, which are essential for salvation, must be held on the doctrinal authority of the church. Attempting to demonstrate such truths by using reason is a waste of time, for the light of reason simply cannot shine brightly enough and needs the help of Catholic teachings. Logic does have an important role to play for theology, however; one can—and in some cases must—use it to investigate theological statements and arguments. With heretics, it is best to stick to analyses of the forms of the arguments they use and to leave the divergence in content to ecclesiastic authority. Theologians must be well versed in logic, since sophistic arguments frequently arise that require careful parsing.21 Later, in his Wisdom commentary, he explains that true seekers can count on God to reveal himself, despite the limits of reason:

It has not been proven by any reason up to now that God exists, or that God is the creator of the world, but to all who bear themselves innocently in God’s sight and use their natural reason to enquire, putting no obstacle in the way of divine grace, God will communicate sufficient knowledge of himself in such a way as to suffice for their salvation. . . . the man who uses his natural reason blamelessly will never lack real knowledge of God.22

(p.49) This is not fideism, for Holcot does not evoke an individual faith, but the security and stability of ecclesiastical authority. Those entrusted with this authority must hold more truths of the faith through belief than those without it, because their duty is to understand and teach the faith. This does not mean that a separate faith exists for the clergy—every statement held true by scripture or the church must be conceded by every Catholic—but that some of the relations of the truths of the faith are the concern of the magisterium alone.

We are left, then, with a sampling of theologians who were writing when the cohesive theological systematizing of figures like Thomas Aquinas and Scotus was no longer an option. While theological problems like the determinism–human freedom issue commanded great interest, the shift of attention from primarily ontological issues to problems involving language and logic made epistemology the field in which theological innovation was necessary. Bradwardine’s De Causa Dei contains little that addresses the difficult questions of how we gain understanding and how we use it as a basis for theological certainty. Those thinkers who do face down this problem are haunted by the specter of skepticism, and, for Wyclif, their results seemed inadequate to address theology’s needs. So his approach was to engage in questions like “what is knowing?” “what is mind?” and “what is the basis for theological science?” to shore up Bradwardine’s approach with reliable, philosophical underpinnings.

Wyclif’s Epistemology: The Mind and the Eye

At this point, it would be very helpful for us to turn to Wyclif’s Sentences commentary, as we can do with figures like Wodeham, Holcot, and Crathorn, to find his developed positions on the questions that defined fourteenth-century Oxford epistemology. While he certainly would have had to construct a Sentences commentary during his theological studies, we have no record of it. The only evidence we have for one are the treatises De Composicione Hominis, De Trinitate, and De Incarnacione, which clearly address questions connected to the commentary tradition.23 The first third of De Trinitate addresses whether theology is a science, but its argument is comprehensible only with familiarity with the fundamental (p.50) questions then current, about knowledge, certainty, and what is involved in understanding.

A glance at a catalog of his Latin works suggests that he had little interest in the problems. The titles of his treatises preceding the Summa de Ente appear to focus on logic, with only the brief De Actibus Anime addressing the problem at hand. And De Actibus Anime, it turns out, does little more than argue that mental acts are indeed properties of the mind and not entities distinct from it. The key lies in seeing through the deceptive title of the collection of treatises known as Tractatus de Logica. Scholars of medieval logic have noted that Wyclif does relatively little formal logic in these early works. While the first treatise, entitled De Logica, is a primer-level introduction to Aristotelian logic, it is not comparable to Paul of Venice’s somewhat later Logica Parva in scope or depth. The remaining treatises, entitled Logice continuacio and Tractatus Tercius, are filled with chapters that begin with formal logical issues, but quickly seem to bog down in frustratingly detailed semantic minutiae. Logice continuacio appears to be two treatises, the first dealing with simple, categorical propositions, while the second deals with propositions involving exceptive terms like “but” or “except.” Tractatus Tercius, by far the most extensive, is devoted to hypothetical propositions. The chapter containing Wyclif’s account of how our vision functions and how it serves as a heuristic device by which to explain our understanding begins with the formidable question of how kinds of terms function within comparative hypothetical sentences. This approach is confusing and obscure for readers used to the more clearly defined structure of a standard Sentences commentary, but patience yields evidence that Wyclif was engaged in the ongoing epistemological dialogue that characterized much of fourteenth-century Oxford thought.

Vision and understanding, which are frequently connected in epistemological theories, had an important relationship for thirteenth- and fourteenth-century philosophers. Roger Bacon had advocated an understanding of the sciences of optics, psychology, epistemology, and logic under the uniting idea that objects generate iterative similitudes, or “species” of themselves into the media that contain them. Just as light moves through the air, from the sun to our eyes, so too does every appearance perceptible move through every medium and into our perception and understanding. This seems both bizarre and not very explicative. How can an individual object emit iterative similitudes of itself, which fly about in the air until they are caught in the organ of sense perception? And how does positing perceptible (p.51) similitudes emitted by objects explain anything about the accuracy of what we perceive? Is this the same as saying that digestion occurs through the stomach secreting a digestive enzyme onto a digestible characteristic in the thing eaten? While a considerable number of thinkers accepted the existence of species to explain perception, Ockham would have none of it. For him, the act of intuitive cognition in which the perceiving mind apprehends an object of perception involved no phantom intermediaries. When I see a tree, I do not see the species of the tree that the tree emits into the atmosphere; I directly see the tree in all its glory. Twenty-first-century epistemologists look wistfully at Ockham’s approach, called “direct perception,” as touchingly naive in its simplicity. Most of his contemporaries regarded it as shortsighted, not least because it did not accurately take into account the optical phenomena of lenses, which anyone could see was the basis for the functioning of the eye.

Vision, Wyclif explains, is the most subtle of our senses, capable of perceiving the greatest diversity, and since it is closest in complexity to the way our understanding works, it is the ideal means of explaining intellection.24 So the best way to explain our understanding is to explain the mechanics of vision. In both sensitive and intellective vision, the vision might be distinct or confused. In both, there are three kinds: direct, when seeing the object directly; refractive, or seeing through a medium; and reflexive vision, as in seeing through a mirror. Our eyes cannot see the finite points of which a thing is made, no matter how distinct the visual act, but our intellective powers are capable of isolating these points, as we will see in Wyclif’s assessment of the Eucharist. Aside from the reference to atomism, Wyclif is not saying anything revolutionary here, although he is simplifying matters considerably. Peter Aureol had taken Scotus’s distinction between intuitive and abstractive cognition and converted it into one between ocular and imaginary cognition, between exterior and interior acts of perception. The latter is not the vision of the understanding that Wyclif describes, but only the imaginative faculty, whereby we call to mind things not immediately evident to the external senses. Wyclif’s predecessors, from Ockham and Scotus onward, intended the distinction between intuitive and abstractive cognition to explain acts of perception, but they allowed the distinction to play at the level of the intellect as well. Indeed, philosophers devoted great care to explicating the relation of interior to exterior acts of perception, and to the analogy of perception and its objects to the understanding and its conceptual objects. In asserting that both species of vision involve degrees of clarity (p.52) and are divisible into direct, reflective, and refractive subspecies, Wyclif is deliberately papering over some very complex issues.25

In his discussion of how human intellectual faculties are deducible from analyses of intuitive and abstractive cognition, John Rodington, O.F.M. (d. 1348) had expressed an interest in the functioning of the eye, especially in whether the visual power is located on the eye’s surface, as Bacon had suggested, or inside the eye, in the optic nerve, as Scotus had thought. Rodington pursued the matter carefully, comprehensively analyzing the theories of vision available to fourteenth-century science. Wyclif’s brief account of the anatomy of the eye, describing the aqueous and vitreous humors, the path of the optic nerves, the dura and pia mater protecting the brain, and the connective web of veins and arteries that “bear life and spirit from the heart, and nutrition from the liver” suggests familiarity with Rodington’s interest in the connection of anatomy and perception. Medieval scientists were not certain that the eye actively sends out rays of perception (as Aristotle had suggested) that meet up with the species being emitted by perceptible objects. Rodington struggled with this question. Alhazen (Ibn al-Haitham c. 965–1039), the Persian scientist whose Kitâb al-Manâzir, known to medievals as De Aspectibus or Perspectiva, was the primary source for optics, thought that “extramission” was nonsense, as would the influential thirteenth-century Polish scientist Witelo, whose Liber Perspectivae would be an important text for fourteenth-century Mertonians. Bacon and Pecham advocated a combination of extramission and intromission, as did Rodington. Wyclif, too, suggests that vision involves both the eye sending something out to contact the object perceived and the eye’s reception of species emitted by the perceived object.26

In Wyclif’s Trialogus, a later work written for the instruction of the educated laity, he argues that an understanding of brain anatomy reveals the different areas in which sense perception is interpreted into thought. In the first ventricle, at the front of the brain, the sensus communis flourishes, where sense data from all of the sense organs are sorted and interpreted into a common sensory language that is interpreted by the higher powers. Here also is where imagination is based, where we construct the illusory stuff of dreams. The estimative and fantastic powers occupy the middle ventricle, where we make judgments about the physical world and, like other animals, “syllogize about particulars,” as when a fox stalks its prey. In the rear ventricle, memory and locomotive power are located, “through nerves in junctures in the back of the spine it is diverted to the other parts (p.53) of the body.”27 Defects in the eye, such as cataracts or trauma to the eye or optic nerve, cause distortion in the objects as they are perceived. Changes in the media through which perception occurs bring about changes in perception itself, as when a torch, when waved in a rapid circular motion at night, appears to be a ring of fire. Wyclif’s gross anatomy of the brain is in keeping with the understanding of his contemporaries; William Crathorn, whose unique epistemology particularly incensed Wyclif, gives a similar account in his Sentences commentary I, q.2, conclusion 4, although he uses cellula where Wyclif uses ventricula.

Why does Wyclif wander into an anatomical explanation of the eye in explaining knowledge? Wyclif’s approach is to follow the lead of a Polish theologian and scientist, Erazmo Witelo (c. 1230–c. 1300), whose thought provides a ready source of heuristic devices throughout Wyclif’s Latin works. Witelo’s Perspectivae is a ten-volume analysis of the science of optics as applied mathematics, and its impact on Western scientific thought was remarkable. For centuries, scientific theorists would make considerable use of Witelo’s approach in their own attempts to mathematize the understanding of physical phenomena. Wyclif’s Parisian contemporary Nicole Oresme (1323–1382) made considerable use of it in his own scientific thought, as did later theorists from Regiomontanus and da Vinci, Galileo and Tycho Brahe, to Descartes. Kepler’s work Ad Vitellionem paralipomena (1604) marks the end of Witelo’s tenure as a scientific authority. More recently, Witelo has been interpreted as being an advocate of the theological light metaphysics best articulated by Grosseteste in De Luce, but this is an overstatement; his interest was in systematizing Alhazen, the great Persian optic theorist, along the lines of Euclidean demonstration.28 Witelo was not a great mathematician, although he was the first to introduce ideas of Eutochius and Apollonius of Pergia into European thought, thanks to the translating work of his contemporary William of Moerbeke. His importance rests in his systematic presentation and application of theory to applied mathematics; Perspectivae appears to have been a particularly important text for Mertonian instruction. Wyclif’s description of the eye in Logica Continuacio is a precis of Witelo’s Perspectivae, book 3. His account of how the species follows a perpendicular line from the object to a point in the core of the eye is that of Witelo, who describes very carefully the function of the aqueous and vitreous humors in the act of perception. Hence, for Wyclif as for other Oxford theorists, optics provided a useful means of modeling and analyzing our understanding of ideas. But what is involved in knowing ideas?

(p.54) Using Logic to Resolve Confusion I: Mental Acts as Qualities of the Mind

Early in his career, Wyclif addressed the nature of the mental act of knowing in De Actibus Anime. He devotes a large portion of the treatise to refuting the position of an unnamed predecessor who believed that mental acts are absolute things capable of per se existence, the way bodies are. Instead, Wyclif argues that the acts of the mind are accidents of the genus action, and not beings distinct from the mind that forms them. The usual assumption that Wyclif is addressing Ockham or his followers is groundless, because neither Ockham nor most of the philosophers who wrote in response to him thought of mental acts as really different from the mind.

Ockham’s innovation was to dismiss the need for species in the act of understanding. Earlier epistemic models, like that of Aquinas, held that we arrive at judgments about extramental objects through an involved process. First, our senses take in the perceptible appearance of some object that is transmitted from the object through the air and received in the senses as “sensible species.” Next, another part of the cognitive apparatus takes these raw sensible species and turns them into mentally encoded “phantasms,” which become the mental image of the object perceived when cognized by the mind. The mind does not yet recognize the object of which it has a mental image, though; the understanding is simultaneously abstracting from the raw sensible species a higher, more comprehensive form of the object perceived by the senses, which Aquinas calls the “intelligible species.” This intelligible species is what Aquinas believes to be the universal, which is converted into a concept, and it is this concept that is used to interpret the mental image. None of these beings by which we comprehend extramental objects, these species or phantasms, can exist on their own; each is an act of the mind the purpose of which is to facilitate understanding. Ockham rejected the existence of species in our act of understanding something extramental, in part because of doubts he had about the reliability of the species’ representation of their object. Instead, we directly perceive the object through “intuitive cognition,” from which the understanding abstracts in a distinct action called “abstractive cognition.”

At an early point in his career, Ockham was willing to concede that the product of abstractive cognition, namely, a concept, might have a kind of being of its own. This being, which he called “objective being” and which today’s philosophers might call “intentional being,” is but a ghost (p.55) in comparison to the being that substances and accidents have. Ultimately, he rejected this objective reality as superfluous, having been convinced by Walter Chatton’s arguments that concepts are merely acts of the mind, with no more being of their own than any other action.29 Very simply, when one runs, there are not two things, the runner and the running, but only one, the runner. When one thinks, there are not two things, the thinker and the thinking, but only one, the thinker.

Ockham’s trimmed-down epistemology was not terribly popular at Oxford. Chatton argued that, in eliminating species, Ockham had destroyed the means by which we distinguish between the acts of the senses and the qualitative contents of those acts. During the 1320s and ’30s, most agreed with Chatton, endorsing the importance of species in the mind’s cognitive processes and differing only in the species’ relation to the mind’s acts of sensing and judgment. The important thinkers, particularly John Rodington, Richard Fitzralph, Adam Wodeham, and Robert Holcot, each argued against Ockham’s reduction of our epistemic machinery. Only William Crathorn, whose epistemology had prompted Holcot to comment that one should only read Crathorn’s Sentences Commentary for laughs, seems a likely candidate for Wyclif’s opponent. While Crathorn, like the others, agreed that species should not be eliminated from the process, he advocated the elimination of mental acts. This leaves only the mind and species, which amounts to a unique epistemology. The mind receives the species, which are reflective of the qualities of the object to which they are connected, and so in cognizing the object, the mind takes on the qualities of the species. “When something is such accidentally, through another, then that other is essentially and through itself.”30 If the species is that through which the mind knows its object, then the species must exist per se. So, when I recognize a white cat before me, the species that contains the qualities of feline-ness, white, furry, quadrupedal, and so forth, is a real being distinct from my mind, but in my mind, meaning that my idea of the white cat is, in fact, white, furry, quadrupedal, and feline.31

Wyclif describes a mental act as likely to be one of three things: it is either nothing but the mind itself, or it is a quality of the mind, accidental and reliant upon it, or it is a thing separate from the mind. He devotes the first half of De Actibus Anime to constructing six arguments against the third possibility, and turns to a discussion of the nature of our ideas about the past in the treatise’s second half. He never addresses arguments against the first possibility, namely, that a mental act is nothing but the mind itself, a position (p.56) which could be a reference to Ockham’s argument that concepts are merely acts of the mind, with no more being of their own than any other action. That Wyclif declines to pursue this suggests that his efforts are indirectly aimed at Crathorn. Crathorn argued that there are no mental acts, only the mind and species, and Wyclif is arguing vigorously for mental acts as qualities of the mind by rejecting the possibility that our ideas are distinct from our minds. If we assume that Wyclif recognizes that there are species distinct from our mental acts, then arguing against the third possibility is sufficient for dismissing the first as well.

Wyclif begins De Actibus Anime by explaining that all of the soul’s actions, its powers, intentions, and habits, are best approached through understanding its acts, which are best known and the ideal medium through which to know the others:

Few or none would disagree that there are acts of the soul. Nobody doubts that at some time [the soul] can sense, understand, wish or eschew, and other particular acts. And it is impossible thus to have one’s self, unless there were a being indicating itself to be in this way; therefore such a being is recognized as such.32

After a little unpacking of the language, the sense of the last sentence should be familiar. Even if one doubts that there are acts of the soul, one cannot doubt that there is something there doing the doubting. This truth, generally connected with the Meditations of Descartes, was well known by the scholastics and had been mentioned by Augustine in De Civitate Dei 11.26 and De Trinitate XI. Scotus and Henry of Ghent made reference to it in arguing against skepticism, while Nicholas of Autrecourt argued that it did not provide sufficient epistemic certainty. In the 1330s, Fitzralph referred to it as reliable evidence that some things can be known with certainty, and Crathorn did as well: “If someone doubts a proposition like this one, ‘I exist,’ it follows that he exists, because this follows: ‘I doubt that I exist; therefore, I exist.’ For anyone who does not exist does not doubt. Therefore no one can doubt this proposition: ‘I exist.’”33

Wyclif includes another approach among his arguments for mental acts as qualities. Acts of the mind, he begins, have attributes that no thing existing on its own could have, which means that they would have to be accidents, beings reliant on the existence of another. Imagine assuming that the statement “every man understands himself to be a non-understanding being” is true. Call the statement A. It is possible to imagine assuming this, (p.57) because we immediately recognize that it is impossible that A is true. “And it is clear that A, when it is understood, does not name its subject [i.e., a member of the set ‘every man’] to be not-understanding, but to be understanding.” If A did designate a man to be not-understanding, it would designate every man to be not-understanding and would be contradicted by the fact that there is somebody who is understanding A. Now, if ideas are things distinct from the mind and per se substantial beings, then some would exist as true and some as false. It would be impossible for one to exist where both its affirmation and its denial leads to a contradiction. But A, if true, would be contradictory, because it would require an understanding man to recognize its truth. If A is false, then there would be some man who does not understand himself to be a non-understanding being. Then that man would be able truly to say “I am not understanding.” But if he were truly saying this, he must have some understanding, at least of what is involved in understanding something, which would be a contradiction. Hence, Wyclif argues that he can imagine a statement the truth and the falsity of which lead to a contradiction, and since no per se substantial being can do this, then this kind of idea, at least, must be reliant on the existence of the mind that comprehends it.

The argument rests on the ontological status of a class of statements that fascinated medieval thinkers, insolubilia, which they used to probe the relations among spoken, written, and mental language. These statements can be understood as a class by thinking of the famous liar paradox, in which the speaker says, “I am lying.” Is the statement true or false? If true, then it is false, and if false, then it is true. Thomas Bradwardine suggested that such sentences signify that they are at once true and false, and Burley responded that all sentences imply that they are the truth. Following Burley’s reasoning, such insoluble sentences are true only if they are both true and false at the same time. Since this is impossible, then all insoluble sentences are simply false. Richard Swineshead had suggested that such sentences are useful in helping us to distinguish between a sentence’s truth and its correspondence to reality. Consider the pair of sentences “this sentence is false” and its contradiction, “this sentence is not false.” The first is itself false, because what it is asserting is the truth. But it does correspond to reality. But the second sentence, its contradiction, does not correspond to reality, so it really is a false sentence, which also makes the contradiction false. Wyclif’s interest in these sentences was so great that he wrote an entire treatise on them, apparently during the same time that he wrote De Actibus Anime.34

(p.58) Using Logic to Resolve Confusion II: Knowing and Belief

In the questions of what knowledge involves, and what the act of knowing is, Wyclif’s approach is to turn to logic to clear up problems that threaten to swamp the project of theology. Wyclif’s conception of what knowledge involves will influence his argument that theology, which involves faith, counts as a science. His discussion in Logice Continuacio is part of a larger analysis of the kinds of terms that need special treatment when parsing the meaning of propositions. The assertion of knowing, or of doubt, within a proposition points to the nature of knowledge itself. If we have knowledge, we have something present to us the certainty of which can be measured. If what we know is certain because anytime we test it, it turns out to be the truth, we have knowledge of a universally holding statement. Knowing that “every fire is hot” is an example of this kind of knowing. Knowing a first principle is even more certain. Once every part of such a statement is understood, the truth of the statement is given. Knowing that “nothing at once is and is not” is like this, since its truth is evident from the very nature of the terms. Finally, knowing a deductively clear truth is the best sort of knowing, Wyclif argues, because such a truth tells us more about the world than the first two. Such a truth, which arises from the conjoining of two simpler statements in syllogistic reasoning, is the basis for deductive science. Here, Wyclif has deductive systems like Euclidean geometry in mind.

But there are more kinds of knowledge than these. Acts of knowing either proceed from these habitually present things known, or they proceed from what is evident to the senses, or from evidence of what could be perceived, if the knower were locally or temporally situated. That is, I might recognize a triangle that I happen upon in architecture or in a painting as being a right triangle, and so know both from what is evident to my senses and from what I have in my head about right triangles. Or I might know that Paris is a beautiful city, even though I’ve never been there. Actual knowing, Wyclif explains, is ultimately belief in the truth of something, without fear of the contrary being true. My actual knowing might be either of a universal, as in knowing what “humanity” is, or it might be of a particular person. Knowing the universal allows me to recognize the particular. Knowing that this recognition is a dependable result, in that I will usually recognize people to be human beings, given my knowledge of humanity, allows me to know with a general certainty that when I meet the (p.59) next person, I’ll recognize her as being a person. But an element of doubt has crept in. There is always the possibility that I might not recognize the next person I meet as a human being, so I can’t say with certainty that I know that I will recognize her.

Actual knowing, which always includes belief, functions on a par with habitual knowing, the term Wyclif uses for the first kind of more certain knowing. If yesterday I saw the pope standing before me, I knew him to be alive at that time, but because I do not now see him, my knowledge of him being alive involves belief that nothing has since happened to him. Strictly speaking, my knowledge about him now is not really knowing: it is believing that counts as knowing. Now, when I saw him standing before me yesterday, there was certainly a degree of belief involved. I believed my senses, and I believed that the man before me was indeed the person he presented himself as being. But now, belief is more of an issue, because while certainty that the pope still lives is high, it is not absolute.

Ordinarily, people don’t make this kind of distinction. We don’t usually measure what we know based on the percentage of slippage caused by the possibility of doubt: “So the laity, who do not doubt or argue about the media that verify the thing believed, frequently know, while the literate, and especially the philosophers, are ignorant.”35 Philosophers can easily let this need for belief lead to problems with skepticism. The right approach to measuring knowing, Wyclif argues, is not to wander in skeptical speculation, but to focus attention on how the language we use about knowing shows what is present to our minds. At a very basic level, a proposition Fx either signifies (a) that you know that there is a given proposition, Fx, or (b) that you know that the proposition Fx signifies a state of affairs about x and F, or (c) that the proposed state of affairs Fx is the truth. Without specifying which way of signifying we have in mind, Fx is something that can be both known and not known at the same time. We can know Fx in the first and the second senses, without knowing whether Fx is really true, in the third sense.

Imagine that you are told that you know a sentence A. Sentence A could be one of two sentences: “God exists” or “a man is an ass.” Now we know at the outset that the first is necessarily true, while the second is impossible. Still, you must admit to the truth of knowing the sentence A, with A’s content being indeterminate. If by indeterminate, we mean “either of the two” (altera istorum), all is well. Even if A most likely stands for the impossible proposition, there is always the chance, since “either of the two” admits (p.60) of both, that the other, necessary sentence is what A stands for. But if by indeterminate, we mean “only one of the two” (alterum istorum), then of course there will be a problem, because the leeway that “either of the two” provides is gone. You commit yourself to either knowing that something is necessarily true, or knowing something that you cannot know. “Either of the two” provides a middle ground, while “only one of the two” does not. The point of this example is to show that how we conceive of the names of the things that are given in a proposition that we claim to know has everything to do with whether we really know what we think we know.

Wyclif’s Arguments for Theology as Science in De Trinitate

By now, the grounds for Wyclif’s argument that theology should indeed be counted among the sciences are clear. He has argued that all knowledge outside of the limited sphere of habitual knowledge of indubitable truths, first principles, and deductively certain conclusions involves an element of belief. Given that belief is the foundation for theological reasoning as well, it follows that theology is a science like any other. Wyclif makes the case for this in De Trinitate, a treatise included in the Summa de Ente, which he appears to have written around 1370. Despite its title, which suggests Augustine’s magisterial work on the Trinity, De Trinitate focuses on several particular problems that had become set pieces for theologians in the mid-fourteenth century. The complexity of the reasoning that had evolved from theologians’ commentaries on book I of Peter Lombard’s Sentences had become breathtaking.

If God the Father (G[f]) generates God the Son (G[s]), meaning that God generates God, God would have to be distinct from God insofar as the Son and the Father differ. Otherwise, insofar as G(f) is not the same as G(s), then God is not God. One way of interpreting this would be to say that “God is different from God.” This could mean that God is not the same as G(f), G(s), and G(hg), which would mean that the Trinity is other than God. Or if G(f) is not the same as G(s), then God the Trinity differs from G(insert a person here). If God is not the same as God, then the difference either lies in number within God, or somehow outside of God, with a distinct God. The former, that there is a difference in number within God, (p.61) cannot be held by reason of the indiscernibility of identicals. But the latter leads to a difference between God as God and God (a person).

Wyclif’s approach to resolving puzzles like this should not be a surprise at this point. Paying attention to how language is used in reasoning about the Trinity, and how that language use pinpoints our ontological commitments, is the key to finding a way out of problems like this one. He had laid the groundwork for his approach to understanding the relation of the persons in the Trinity earlier, between 1366 and 1368, in Purgans Errores circa Universalia in Communi:

In predication according to essence the singular and its universal are distinct, since the singular is one, as the universal another individual. It does not follow, “these are distinct things, so to these we assign number” because through most general and most singular demonstrating of its supposit, any things distinct are these, yet they are not held numerable, since one of them remains. Thus they are distinct formally, but not formally distinct things. Nor are they formally “these two” [indicating this universal and this singular] but they are this, and so the differences are to this sense, that these differ, but not through numerical difference; because only by difference formally or according to reason are they “these.”36

The details of Wyclif’s use of Scotus’s formal distinction in his own approach to resolving issues like this are manifold, incorporating ontological questions of how God might function as a universal of which the divine persons are particulars, as well as semantic problems as deeply rooted as how to use analogy in talking about God. While these details illustrate Wyclif’s conviction that his metaphysical realism is the ideal approach to the complex questions that had developed in the previous decades, our interest here lies in his more general arguments for recognizing theology as foremost among the sciences. Augustine had famously argued that we can come to appreciate the triune nature of God by using our reason to recognize the trinities in nature, most particularly the threefold nature of the human mind: reason, memory, and willing. This use of human reason to reach truth about divinity was among the many called into question by fourteenth-century theologians. Wyclif was not the first to argue that Augustine’s approach was valid; Richard Fitzralph argued that the human mind is an imperfect image of the Trinity in his Sentences Commentary.37 Before addressing this issue, the more general question of whether, given (p.62) the skeptical tendencies that affected fourteenth-century philosophy, we can even use our reason for such a problem needs to be answered.

Wyclif was not the first to raise the banner for theology as a science in response to the moderni. We have seen that Bradwardine’s thought in De Causa Dei presupposes some kind of connection, although he did not articulate it. Further, Aston had shown that we can use logic to demonstrate the necessity of God’s being, even if we cannot actually argue from created being to the divine as Aquinas and Scotus had thought. Finally, Richard Brinkley, O.F.M. (f1. 1355–1375) appears to have blazed the path for Wyclif in arguing that man can, by evident reason, infer that human life is itself ordered to another life than the present. Sadly, we do not have Brinkley’s Sentences commentary, and all that remains appears to be an abbrevatio prepared by Etienne Gaudet, a Parisian scholar in the 1360s.38 Further work on Brinkley will likely yield evidence of his influence on Wyclif.

Wyclif believed that when human reason establishes God’s existence, it also establishes the triune nature of the divine essence, even if the demonstrator is unaware of this feat. His interest in relating our rational recognition of God’s existence is limited. Elsewhere, he asserts that it is part of our fallen nature that we do not know created beings as they are in their universals, but come to knowledge of universals from their particulars. That is, we come to know the universal X by knowing individual x’s. Yet within us, he argues, is the possibility of knowing divine things: “Any such created nature has an innate concrete knowledge by which it knows things as they are in their natural order, and thus the soul has innate comprehensions which it does not receive from the things of sense.”39 Apparently, then, we know innately of God’s existence and have no need of a demonstrative proof. In Trialogus, Wyclif’s character Phronesis, the wise theologian, says, “God’s existence is the first thing following from any truth, such that a formal contradiction would arise when holding something to be, or something to be in some way, without first recognizing God to exist.”40 In our discussion of the first treatises of Summa de Ente in the next chapter, it will turn out that anyone with a clear understanding of being will recognize that God’s existence is necessary for the being of, and our knowing of, anything in creation.

Authorities like Anselm, Augustine, the Victorines, and Grosseteste all argue that the Trinity is evident through recognition of trinities in creatures, natural signs by which we can deduce syllogistically the divine Trinity. Augustine’s arguments show that reason allows us to recognize the (p.63) divine truths woven into creation, but in each case the faith must serve as foundation. “This is generally said,” Wyclif continues, “that no one can assent to this deduction [of the threefold divine nature from perceived created trinities] without faith, and so it is not merely natural, and is not demonstrated in the natural light.”41 But if faith is the foundation, is demonstration through natural reasoning impossible? All reasoning demands some sort of nonrational assent, Wyclif argues, either before or outside of the reasoning process, to conditions that serve as evidence for the reasoning to take place. Learning to read or to speak requires a degree of faith in the teacher. The absence of the light of faith infused in the mind allows one to give assent to many ideas, but in each case, the mind craves evidence of some kind. The testimony of authority counts as such even in matters otherwise neutral, so assent can be given in these matters from the authority of scripture or teaching that will be, in light of divine reality, rationally clear to all.

Later in his life, Wyclif made a similar argument in Trialogus, where his foil, Pseustis, argues a simplified version of the Ockhamist position. His champion, Phronesis, responds:

It is impossible for the faithful or the heretic to know something, unless they know it fundamentally through faith; because just as nobody knows letters—that one is A, the next B, and so of other—unless they believe, so nobody by their senses know[s] anything sensible, unless first truth speaks and teaches that, that a thing is sensible in one way or in another.42

Faith is not judged to be better relative to the wealth of evidence available; the faith of a rich man with a Bible is not superior to that of a poor man without one. Not all acts of faith result in immediate understanding. Sometimes, we believe something, yet never understand it, while at other times, we come to an understanding immediately on giving assent to it, and at still others, what is believed is only understood after thought. This shows that not all faiths are of a kind.

But are they always present in any act of knowledge? And if so, and if faith is a virtuous qualitative habitus, which all theologians recognize to be a theological virtue, can we know anything without the assistance of grace, which is necessary for any theological virtue? Wyclif is not clear on the place of illumination in knowledge in De Trinitate, although he does argue that grace is necessary for any virtuous act in De Dominio Divino III. We must deduce his allegiance to Augustine, Grosseteste, and Bonaventure. (p.64) Their position was that every act of understanding entails the divine illumination of the mind, a participation in the light of Truth every time we apprehend the truth. Aquinas and Scotus limited the need for this illumination to the sphere of revelation, arguing that the unassisted human reason is capable of accurately perceiving the truth about things in this world without the need of divine assistance. Faith factors into this question when truths understood by pagans such as Aristotle must be explained; Aristotle lacked the Christian faith, yet reasoned out the truth of things in the world. This led Aquinas to conclude that one could not have faith and knowledge about the same thing. Faith requires assent without evidence, while knowledge entails having that evidence. Henry of Ghent (d. 1293) is the last widely studied philosopher to have argued the need for divine illumination before Nicholas of Cusa in the fifteenth century. By the shape of Wyclif’s arguments here, it is difficult to avoid concluding that he followed Henry, Bonaventure, and Grosseteste in arguing the need for divine illumination. “For it is impossible for a creature to know anything unless it knows it through grounding from the authority of God teaching and moving to assent.”43

All that we understand, then, requires some faithful assent of the human mind, some acquiescence to evidence that might be doubted. In the case of understanding objects we perceive, our intuition of sense data entails faith, which kindles the growth of knowledge as our experiences increase and leads to acts of judgment about the world. Faith has a natural place in all of our acts of understanding, great and small, and if we can claim to have an accurate explanation for even the least act of understanding the simplest thing, we should also admit to the possibility that great truths of faith, like the Trinity, may be explored and understood by human reason. If the articles of faith were demonstrable scientifically, philosophers would already have done so, without the need for revelation. But the articles of faith are subtle, hidden from natural light. The merit that comes from faith consists in voluntarily and humbly submitting the sensibility to the authority of the Catholic church and the articles of faith, against which rebellion is a sin. So to view faith and reason as incompatible is premature. Faith is at once an act of believing, a habit, an assent to a truth; since what is known is believed as well, faith and knowing are not really incompatible.


(1.) See R. L. Poole’s introduction to DD, xxi. The groundbreaking survey of the philosophy and theology of the period remains The Cambridge History of Later Medieval Philosophy, ed. Norman Kretzman, Anthony Kenny, and Jan Pinborg (Cambridge, 1982). Accompanying this is The Cambridge Translations of Medieval Philosophical Texts, a set of anthologies exemplifying (p.250) the development and breadth of later medieval thought. See volume 1, Logic and the Philosophy of Language, ed. Norman Kretzman and Eleonore Stump (1988); volume 2, Ethics and Politics, ed. A. S. McGrade, John Kilcullen, and Matthew Kempshall (2001); volume 3, Mind and Knowledge, ed. Robert Pasnau (2002). Volume 2 contains Kilcullen’s translation of the first ten chapters of Wyclif’s DCD I.

(2.) See Marilyn McCord Adams, William Ockham (Notre Dame, Ind., 1988), 2 vols.; Paul Vincent Spade, A Cambridge Companion to Ockham (Cambridge, 1999). For an overview of Oxford’s “golden age,” see William Courtenay, Schools and Scholars in Fourteenth Century England (Princeton, N.J., 1987).

(3.) Hester Gelber, It Could Have Been Otherwise: Contingency and Necessity in Dominican Theology at Oxford 1300–1350 (Leiden, 2004), 313n9; reference is to Scotus’s Ordinatio I, d.44, in Opera Omnia, ed. Charles Balic (Vatican City, 1963), 6, 363.17–364.10.

(4.) William Ockham, Quodlibetal Questions, trans. Alfred Freddosso (New Haven, Conn., 1991), vol. 2, 491.

(5.) See William Courtenay, Capacity and Volition (Bergamo, Italy, 1990).

(6.) See ibid., 265–266; also Gracia 674–675. The influence of Chatton on Wyclif deserves much fuller consideration than is possible here, where Wyclif’s more immediate opponents are of interest. See Girard Etzkorn and Joseph Wey, eds., Reportatio in I Sent. Dist. 1–9 and Dist. 10–48 (Toronto, 2002), 2 vols.

(7.) Adam de Wodeham, Lectura Secunda in Librum Primum Sentatiarum, ed. Rega Wood and Gedeon Gàl (St. Bonaventure, N.Y., 1990). “Et ideo ad variationem mediorum secundum speciem variatur actus sciendi secundum speciem, et diversae scientiae non probant formaliter eandem conclusionem per idem medium, nisi mendicando” (d.1, q.3.12, 247).

(8.) Ibid., vol. 2, “Et ideo nisi per fidem nobis innotuisset quod una res est tres res, credidissemus firmiter sophismata praedicta bona fuissa argumenta” (d.2, q.1.13, 25).

(9.) See Norman Kretzman and Barbara Ensign Kretzman, The Sophismata of Richard Kilvington (Cambridge, 1990); Edith Dudley Sylla, “The Oxford Calculators,” in Kretzman, Kenny, and Pinborg 1982, 540–563.

(10.) John E. Murdoch, “Mathesis in Philosophiam Scholasticam Introducta: The Rise and Development of the Application of Mathematics in Fourteenth Century Philosophy and Theology,” in Arts Libéraux et Philosophie au Moyen Age (Montreal and Paris, 1969), 215–254.

(11.) Curtis Wilson, William Heytesbury: Medieval Logic and the Rise of Mathematical Physics (Madison, Wisc., 1956); Marshall Clagett, The Science of Mechanics in the Middle Ages (Madison, Wisc., 1959).

(12.) See Opus oxoniense I, d.III, q.4, in Philosophical Writings, trans. Allan Wolter (Hackett, 1987), 97–132, esp. 106–115.

(13.) Philosophically, the term “nominalist” today suggests an ontology generally more sparse than the Aristotelian categories to which Ockham was committed. While Ockham believed that universals have no reality beyond the concepts we use to describe things, he also believed that there are spatiotemporal objects that exist independently of our perceptions, with properties and relations independent of our concepts. The philosophical antirealism that can be associated with contemporary nominalism is foreign to the “nominalism” of the medieval thinkers. For an overview, see D. M. Armstrong, Universals and Scientific Realism (Cambridge, 1978), or his Universals: An Opinionated Introduction (Boulder, Colo., 1989).

(14.) See Nicholas of Autrecourt, The Universal Treatise, trans. Leonard Kennedy, Richard Arnold, and Arthur Millward (Milwaukee, Wisc., 1971).

(15.) Leonard Kennedy, “Philosophical Scepticism in England in the Mid-Fourteenth Century,” Vivarium 21.1 (1983): 43–44. Kennedy’s survey of fourteenth-century skeptical tendencies here and in his “Late-Fourteenth-Century Philosophical Scepticism at Oxford,” Vivarium 23.2 (1985): 124–151, are useful resources, although his The Philosophy of Robert Holcot: A Fourteenth Century Skeptic (Lewiston, Maine, 1993) overemphasizes the place that skepticism had in Holcot’s thought. See also Paul A. Streveler, “Gregory of Rimini and the Black Monk on Sense and Reference,” Vivarium 18.1 (1980).

(16.) L. L. Hammerich, The Beginning of the Strife between Richard Fitzralph and the Mendicants (Copenhagen, 1938), 20.74–80. See also Katherine Walsh, A Fourteenth-Century Scholar and Primate: Richard Fitzralph of Oxford, Avignon, and Armagh (Oxford, 1981).

(17.) Augustine, On the Teacher, II.38, trans. Peter King (Hackett, 1995), 139. See Gareth Matthews, “Knowledge and Illumination,” in The Cambridge Companion to Augustine, ed. Eleonore Stump and Norman Kretzman (Cambridge, 2001), 171–185.

(18.) Gordon Leff, Richard Fitzralph: Commentator on the Sentences (Manchester, 1963); see also Katherine Tachau, Vision and Certitude in the Age of Ockham (Leiden, 1988), 236–242. I am grateful to Dr. Michael Dunne for his advice about the likelihood of Fitzralph’s authoring the question discussed.

(19.) Kennedy 53. See Joel L. Bender’s “Nicholas Aston: A Study in Oxford Thought after the Black Death,” Ph.D. diss., University of Wisconsin, 1979, for a well-rounded study of this overlooked figure.

(20.) See Holcot’s denial of the possibility of establishing God’s existence through unaided reason, “non habemus ab aliquo philosopho demonstrative probatum quod aliquis angelus est, neque de deo, neque de aliquo incorporeo,” 144, in J. T. Muckle, C.S.B., “Utrum Theologia Sit Scientia: A Quodlibetal Question of Robert Holcot, O.P.,” Mediaeval Studies 20 (1958): 127–153.

(21.) Quodlibet 87, Utrum haec est concedenda: Deus est Pater et Filius et Spiritus Sanctus, in Hester Gelber, Exploring the Boundaries of Reason: Three Questions on the Nature of God by Robert Holcot, OP (Toronto, 1983), 34–36.

(22.) Robert Holcot, Super Libros Sapientiae (Hagenau, 1494; rpt., Frankfurt, 1974), lect. 155, translated by Beryl Smalley in English Friars and Antiquity in the Early Fourteenth Century (Oxford, 1960), 185.

(23.) It is still too soon to declare certain treatises to have been included in Wyclif’s Sentences commentary. This line of reasoning was introduced by J. A. Robson in Wyclif and the Oxford Schools (Cambridge, 1961); I explore it more in “Wyclif’s Trinitarian and Christological Theology,” in A Companion to John Wyclif, ed. Ian Levy (Leiden, 2006), 127–198, but further documentary research is needed.

(24.) See also De Trinitate, chap. 10, 110.

(25.) See Katherine Tachau, Vision and Certitude in the Age of Ockham: Optics, Epistemology and the Foundations of Semantics 1250–1345 (Leiden, 1988), for a definitive history of the complexities of early fourteenth-century epistemology. For Peter Aureol, see Scriptum proem I, 204–205 (Aureol’s Sentences Commentary in its second version), in E. Buytaert, ed., Petri Aureoli Scriptum super primum Sententiarum, prooemium-dist. 8, 2 vols. (St. Bonaventure, N.Y., 1953–1956); Tachau 85–112. For Scotus on intuitive cognition, see Sebastian Day, Intuitive Cognition: A Key to the Significance of the Later Scholastics (St. Bonaventure, N.Y., 1947); Allan Wolter, “Duns Scotus on Intuition, Memory, and Our Knowledge of Individuals,” in The Philosophical Theology of John Duns Scotus, ed. Marilyn McCord Adams (Ithaca, N.Y., 1990).

(26.) For Rodington, see Tachau 216–236; for Bacon, Pecham, and Witelo on optics, see David C. Linberg, “Lines of Influence in Thirteenth-Century Optics: Bacon, Witelo, and Pecham,” Speculum 46: 66–83; for Witelo, see Sabetai Unguru, “Witelonis Perspectivae Liber Primus,” Studia Copernicana 15 (1977).

(27.) Trialogus II.6.

(28.) See Unguru 12–40.

(29.) See Eleonore Stump, “The Mechanisms of Cognition: Ockham on Mediating Species,” in Spade 1999, 168–203.

(30.) Translated by Robert Pasnau, in The Cambridge Translations of Medieval Philosophical Texts: vol. 3, Mind and Knowledge (Cambridge, 2003), 255.

(31.) For Crathorn, see Quaestiones super librum sententiarum, in Questionen Zum ersten Sentenzenbuch, ed. F. Hoffmann (Münster, 1988); also Sent. I, q.1, trans. Pasnau; Tachau 255–274; Robert Aurélien, “William Crathorn,” in Stanford Encyclopedia of Philosophy, available at http://plato.stanford.edu/entries/crathorn/#8b.

(32.) De Actibus Anime I, 1.1–10.

(33.) Pasnau 298–299. See also Adams, William Ockham, vol. 1, 552–571, for Henry of Ghent’s position, and William Frank and Allan Wolter, Duns Scotus, (p.253) Metaphysician, 125, 167. See Julius Weinberg, Nicholas of Autrecourt (Princeton, N.J., 1948), and Constantin Michalski, Le Criticisme et le Scepticisme dans la Philosophie du XIVe Siècle (Cracow, 1926), reprinted in La Philosophie au XIVe Siècle: Six Etudes (Frankfurt, 1969), 100. On the differences between Descartes’ use of this argument and Augustine’s, see Gareth Matthews, “Si fallor, sum,” in Augustine: A Collection of Critical Essays, ed. R. A. Markus (New York, 1972), 151–167.

(34.) Insolubilia literature is extensive in medieval logic. See Paul V. Spade, “Insolubilia,” in CHLMP 246–253, and also online at The Stanford Encyclopedia of Philosophy. See Johannis Wyclif: Summa Insolubilium, ed. Paul V. Spade and Gordon Wilson (Binghamton, N.Y., 1986).

(35.) De Logica, vol. 1, 181.

(36.) Purgans Errores circa Universalia in Communi, De Ente I, Tractatus IV, chap. 5, in Johannis Wyclif De Ente Librorum Duorum (WS 1909), 47.7–22.

(37.) See Gordon Leff, Richard Fitzralph: Commentator on the Sentences (Manchester, 1963), 52–55. My thanks are due to Michael Dunne, who kindly provided me with a draft of his edition of Fitzralph’s discussion in I, q.5, a.6.

(38.) Zénon Kaluza, “L’ouevre théologique de Richard Brinkley, OFM,” Archives d’Histoire Doctrinale et Littéraire du Moyen Age 56: 169–273.

(39.) Summa de Ente, Libri Primi: Tractatus primus et secundus, ed. S. Harrison Thomson (Oxford, 1930), xxv (translation by Thomson).

(40.) Trialogus I, i.

(41.) DT, chap. 1, 3: “Hic dicitur communiter, quod nemo potest sine fide prima assentire isti deduccioni, et ideo non est mere naturalis, et sic non demonstratur in lumine naturali.”

(42.) Trialogus I.6, 55.

(43.) DT, chap. 2, 19.