Burley, Walter

(b. England, ca. 1275; d. ca. 1345?)

logic, natural philosophy.

A colophon to the final version of Burley’s commentrary on the Logica vetus that is dated 1337 stipulates that the work was composed in its author’s sixty-second year, a factor which places Burley’s birth about 1275, possibly in one of the two towns named Burley in Yorkshire. Although almost nothing is known of his youth, it seems most reasonable to presume that Burley began his studies at Oxford sometime during the last decade of the thirteenth century, for two works dated 1301 and 1302 already designate him as a master in arts. He may have at this time also been a fellow of Merton College, although the first definite connection we have with Merton derives from the bursorial roll of 1305. It seems very probable that, during his regency in arts at Oxford, Burley composed his earliest versions (later to be revised and expanded) of expositions on almost all of Aristotle’s works in logic, natural philosophy, and moral philosophy.

In 1310 (at the latest) we find him in Paris, where he began his theological studies, a stage in his career first definitely documented by his citation as doctorsacre theologie in a colophon dated 1324. We lack further information concerning Burley’s work as a theologian and have thus far not been able to discover his Commentary on the Sentences, but his first treatise dealing with the intension and remission of forms (theso-called Tractatus primus written between 1320–1327) indicates that Thomas Wilton, also a former fellow of Merton College, was at some point his socius and master of theology in Paris.

Burley most likely remained in Paris until 28 February 1327, at which time he was appointed as an envoy of Edward III to the papal court. Indeed, the official connections Burley then began with English public figures seems to have continued, intermittently, for the remainder of his years. Yet this is not to say that this new phase to his career marked the end, or even a substantial lessening, of his academic pursuits. For, just as during his years in Paris, he continued to set down numerous logical and philosophical works.

In Bologna in 1341 for a disputation and again at Avignon in November 1343, our last document mentioning Burley is a register revealing his acquisition of a rectory in Kent on 19 June 1344. It seems unlikely that he lived much beyond that date.

In terms of the literary activity, Burley remained, throughout his career, fundamentally an arts graduate. For, if one sets aside his lost work on the Sentences, all but one or two items among the formidable mass of his writings deal with logic and philosophy. He was, to begin with, an Aristotelian commentator with a vengeance, composing two—sometimes three—different versions of a commentary on a single work.

Thus, he wrote commentaries on all of the Aristotelian logical books, including Porphyry’s Isagoge and the Liber de sex principiis ascribed to Gilbert de la Porrée, apparently formulating an initial version of his comments during his earlier Oxford period. Many of the commentaries were late revised, the final version of his complete Expositio super artem veterem being written only in 1337. To this already very substantial body of logical literature one must add Burley’s numerous opuscula and treatises on the so-called parva logicalia (which constituted, in large part, medieval additions to the logic of Aristotle) and, in particular, the two redactions of his magnum opus in logic, the De puritate artis logicae. The earlier, shorter version of this work appears to have been composed (in incomplete form) before the appearance (ca.1324) of the Summa logicae of William of Ockham. Indeed, the second version (1325–1328) of Burley’s treatise can in many respects be viewed as a reply to some of Ockham’s contentions. Yet it is not merely as an anti-Ockhamist tract that Burley’s revised De puritate artis logicae is of importance; for, at least in the view of its modern editor, Philotheus Boehner, its implicit subsumption of syllogistic under the more general theory of consequences involving unanalyzed propositions strongly suggests Burley to have been a logician of appreciable competence.

As concerns natural philosophy once again one must begin by noting the extensive roster of Burley’s Aristotelian commentaries: Expositiones or Questiones (and again often in multiple versions) on the Physica, De caelo, De generatione et corruptione, Meteorologicda, De anima, Problemata, Parva naturalia, De motu De anima, orbis. Of these commentaries, those on the Physics are undoubtedly the most important. The earliest version appears to have been written at some point before 1316. Apparently also of an early date are the separate Questiones on the Physics, extant in a single (incomplete) manuscript (MS Basel, Universitätsbibliothek F.V.12). We are more fully informed, however, concerning Burley’s definitive version of his comments on the Physics: Book I was finished in Paris in 1324, Books II-VI, again in Paris, by 1327, while the final redaction of Books VII-VIII was written between 1334–1337. Although this last effort which Burley devoted to the exposition and analysis of Aristotle’s Physics contains, it appears, the most significant of his contributions to natural philosophy, at least some of what he has to offer here also appears, in more elaborate form, within various independent treatises and opuscula, most notably the Tracdtus de formis (which contains his criticisms of Ockham’s identification of substance and quantity), the quodlibetal question De primo et ultimo instanti, and his two treatises on the intension and remission of forms (resp. the Tractatus primus and Tracttus secundus).

Burley turned to moral philosophy and varia rather late in his life, completing his exposition of Aristotle’s Ethics in 1333–1334 and of the Politics in 1340–1343. His immensely popular history of philosophers, the De vita et moribus philosophorum, also appears to derive from the early 1340’s.

If one excludes Burley’s importance within the history of formal logic, it is clear that the very small segment of his voluminous work within natural philosophy which has hitherto received careful study makes any estimate of his significance for the history of later medieval science radically incomplete and tentative. Yet in spite of this, there are two of Burley’s contentions which, to judge merely from the attention they received within the works of other medieval natural philosophers, are surely to prove of more than ephemeral importance: his view of the proper limits to be assigned temporal processes through the ascription of first or last instants, and his view of the nature of motion.

De primo et ultimo instanti. This brief treatise was a quodlibetal question disputed by Burley at Toulouse sometime before 1327. Its subject derived directly from Aristotle’s discussion in the Physics (Book VI, ch. 5, and Book VIII, ch. 8) of the problem of first and last moments within a given change which occurred over a given time interval. Without unraveling Aristotle’s treatment and proposed resolution of the puzzle, suffice it to say that Burley (and a multitude of other Scholastics as well) correctly focused upon the relevant variables within the problem as stated by Aristotle when they formulated what was to become a standard distinction concerning the first and last instants of a given temporal process or change. Briefly, the change may be limited intrinsically at both ends (incipit et desinit) by an instant which belongs to the temporal interval covering the change in question (primum vel ultimum instans esse), or limited extrinsically by a first or last instant which does not belong to the appropriate interval (primum vel ultimum instans non esse), in which case, of course, an ultimum instans non esse, immediately precedes the time denominated by the change, while a primuminstans non esse immediately follows it. Given this, in four regulae Burley explicitly stipulates the mutual exclusiveness of intrinsic and extrinsic instants as limits for both the beginning and the completion of a given change. The problem is then, however, to decide just which kinds of things can be said to begin or end by possessing just which kind(intrinsic or extrinsic) of limit. Although the many cases that Burley considers in making this decision involve complexities that cannot be expounded here, some notion of his procedure should be indicated. Thus, a res successiva, a given temporal motion or change or a time interval itself, can, following Aristotle, only have extrinsic limits at both ends. The same is true of a res permanens which depends in its being on a res successiva (the truth of the proposition “Socrates is running” is Burley’s example of such a res permanens, since it depends on the existence of a given run of Socrates, which is a res successiva). On the other hand, intrinsic limits are naturally appropriate when a given permanent thing itself has only instantaneous existence. And Burley goes on to ascribe what he feels to be proper limits to other cases of res permanentes undergoing change, specifically to changes explicable in terms of the intension and remission of forms as viewed under his own special theory concerning the nature of such intension and remission.

On the Nature of Motion. Indeed, to state Burley’s view with respect to this much discussed problem of motion is, in effect, to set forth the basis of his theory of intension and remission of forms, a theory most elaborately developed and expressed in his Tractatus primus. Some theorists, of whom Ockham is a prominent but not the earliest example, had argued that motion consists of nothing else besides the mobile and the place, quality, or quantity that it successively acquires. The form successively acquired was called (1) the forma fluens. Burley admitted that it could also be considered as (2) a flux (fluxus formae), or (3) a successive quantity. As a flux, motion was the acquisition of the terminus of motion or the transmutation by means of which the terminus was acquired. As a successive quantity, motion was the measure of the motion taken in the second (fluxus) sense. Motion as a forma fluens belonged to the same category as its terminus (place, quality, or quantity); as a fluxus formae it either belonged to or constituted the whole of the Aristotelian category of passions or affectations; as a successive quantity, it belonged to the category of quantity.

Why was it necessary, according to Burley, that motion be not only a forma fluens but also a flux? For Burley, places, qualities, and quantities were individual and simple. A body at a given time had only one place, one quality of a given type, and one quantity of a given type. In the case of quality, for example, the not uncommon assumption that a compound simultaneously contained both hot and cold combining to produce a single sensible result was to Burley not only false, it was self-contradictory. Qualities like hot and cold were for him sensible by definition. They were not hypothetical underlying realities without separate effect. It followed further, on this view, that one quality could not be part of another. Similar conclusions could be applied to place and quantity.

Since this was Burley’s view of the forms to be acquired, his conception of the forma fluens theory could not be the same as Ockham’s. Ockham spoke of the form acquired or the terminus of motion, and assumed that this final form somehow contained the forms acquired along the way. A single form was acquired part by part, and this was the forma fluens. For Burley, every instant of motion corresponded to a different from, and these forms were neither part of, nor contained in, the terminus of motion. The forma fluens was any one of these instantaneous forms, but no one of these forms could represent the whole motion since the terminus (with successive acquisition assumed) represented the whole motion for Ockham. To represent more than an instant within a motion, Burley needed another existential referent. He might have chosen the entire collection of instantaneous formae fluentes. Durand of St. Pourcain did just this, saying that the continuity of these forms unified them (cf. Maier, Studien, II, 70–73). For Burley, the forms, analogous to points, could not be continuous, and hence could not be treated as a unity. As a unified referent he chose instead the means by wahich the forms were acquired, i.e., the transmutation or flux. The forma fluens conception, he admitted, was truer to the physical reality of motion (entitas rei), but the fluxus formae conception was truer to the significance of the term “motion”(Physics, BK.III, Text 4).

If Burley’s views of motion are typical of other parts of his physics as yet less well-known, the motivation for his conclusions was not simply a willingness to multiply entities beyond necessity, necessity, but also his view of forms as empirical, simple, and separate, and his refusal to assume hypothetical connections between them.

BIBLIOGRAPHY

1. Life and Writings. The three fundamental articles are A.B. Emden, Biographical Register of the University of Oxford to A.D. 1500 (Oxford, 1957–1957), I, 312–314; Conor Martin, “Walter Burley,” in Oxford Studies Presented to Daniel Callus (Oxford, 1964), pp. 194–230; J.A. Weisheipl, “Ockham and Some Mertonians,” in Mediaeval Studies, 30 (1968) (174–188. Father Weisheipl will also shortly publish his “Repertorium Mertoniense” in a future vollume of Mediaeval Studies, which will include a complete list, together with editions and extant manuscripts, of Burley’s works. Cf. Zofia Wlodek, “Les traités de Walter Burleigh dans les manuscrits des bibliotheques en Pologne,” in Mediaevalia philosophica polonorum, 11 (1963), 152–156.

II. Texts of Burley’s Works.Early printed Editions and Manuscripts. (Note: Only selected early editions and a few MSS of works important within the history of science are listed; see Weisheipl’s forthcoming “Repertorium Mertoniense” for a complete listing.) Expositio super artem veterem (final version completed 1337; Venice eds., 1481, 1497, 1519). Exkpositio super libros duos posteriourm analyticorum (Venice, 1497). De sophismatibus, in St. Bonaventure, Opera omnia (Bassani, 1767), cols.467ff. Tractatus de universalibus realibus (Venice, 1492–1493). Exysicorum librorum physicorum, the defintive version(Venice, 1482, 1491, 1501; Bologna, 1589. Expositio librorumphysicorum (early, pre-1316version), MS Cambridge, Gonville & Caius 448/409, pp172–543. Questiones super libros physicorum (also early; incomplete, Books 1-IV only), MS Basel, Universitatbibliothek, F.V.12, ff.108r-171v. Expositiones super libros: (1) De anima; (2)Parva naturalis; (3)De generatione et corruptione; (4) De caelo; (5) De substantia orbis; (6) De motu animalium, Ms Vat. lat. 2151, lr-108v, 149r-256r. Tractatus de formis, MSS Vat. lat. 2151, ff. 131r-148r; Vat. lat. 2146.2146, ff. 252v-256v. Tractatus primus (sive Tractatus de activitate, unitate et augmento formarum activarum habentium contraria suscipientium magis et minus), Ms Vat. lat. 817, ff. 203r-223r. Tractatus secundus (sive Tractatus de intensione et remissione formarum) (Venice, 1496). Opuscula varia, MSS Vat. lat. 2146, ff. 235r-256v; Lambeth Palace 70, ff. 8r-306r. Expositio librorum ethicorum (Venice, 1481, 1500).

Modern Editions. See De puriate artis logicae, Tractatus longior, With a Revised Edition of the Tractatus Brevior, Philotheus Boehner, ed. (New York, 1955). Part 1 of Tractatus II of the Tractatus longior was republished, together with a brief introduction and an English transiation, by Ivan Boh, “Burleigh; On Conditional Hypothetical Propositions,” in Franciscan Studies, 23 (1963), 4–67. “De primo et ultimo instanti,” Herman and Charlotte Shapiro, eds., in Archiv für Gechichte der Philosophie, 47 (1965)157–173, Shapiro has also published—sometimes with the assistance of others—editions of the following brief opuscula of Burley; “De relativis,” in Franciscan Studies, 22 (1962), 155–171; “De qualitatibus,” in Franziskanische Studien, 45 (1963), 256–260; “De deo, natura et arte,” in Medievalia et humanistica, 15 (1963), 86–90; “De diffinitione,” in Mediaeval Studies, 27 (1965), 337–340; “De potentia activa et passiva,” in Archives d’histoire doctrinale et littéraire du moyen age, 24 (1966), 299–303; and “De sensibus,” in Mitteilungen des Grabmann-Institutes der Universitāt München, Heft 13 (Munich, 1966). De vita et moribus philosophorum has been edited, together with an old Spanish translation, by H. Knüst (Tübingen, 1886); cf. J. O. Stigall, “The Manuscript Tradition of the De vita et moribus philosophorum of Walter Burley,” in Medievalia et humanistica, 11 (1957), 44–57, and J. N. Hough, “Platus, Student of Cicero, and Walter Burley,” ibid., pp. 58–68.

III. Secondary Literature. A. Logic. Philotheus Boehner’s high opinion of Burley as a logician is succinctly stated in his Medieval Logic. An Outline of Its Development from 1250 to c. 1400 (Chicago, 1952), pp. 44–51, 84–89. This opinion, seemingly shared by Boh (vide supra et infra), has been criticized by L. Minio-Palluello in Oxford Magazine, 71 (1953), 200–201. A. N. Prior, “On Some Conse-quentiae in Walter Burleigh,” in New Scholasticism, 27 (1953), 433–446. Ivan Boh, “A Study in Burleigh: Tractatus de regulis generalibus con sequentiarum,” in Notre Dame Journal of Formal Logic, 3 (1962), 83–101; “Walter Burleigh’s Hypothetical Syllogistic,” ibid., 4 (1963), 241–269; “An Examination of Some Proofs in Burleigh’s Propositional Logic,” in New Scholasticism, 38 (1964), 44–60. Ernest A. Moody, Truth and Consequence in Mediaeval Logic (Amsterdam, 1953) passim.

B. Natural Philosophy and General. Absolutely fundamental are the five volumes of Anneliese Maier’s Studien zur Naturphilosophie der Spätscholastik, which contain numerable expositions and analyses of aspects of Burley’s work within the context of similar material as treated by other late medieval Scholastics: I. Die Vorläufer Galileis im 14. Jahrhundert, 2nd ed. (Rome, 1966); II. Zwei Grund-probleme der scholastischen Naturphilosophie, 3rd ed. (Rome, 1968); III. An der Grenze von Scholastik and Natur-wissenschaft, 2nd ed. (Rome, 1952); IV. Metaphvsische Hintergru tide der spätscholastischen Naturphilosophie (Rome, 1955); V, Zwischen Philosphie and Mechanik (Rome, 1958).

Other articles by Maier also directly concerned with Burley are “Zu Walter Burleys Politik-Kommentar,” in Recherches de théologie ancienne et médiévale, 14 (1947), 332–336: “Zu einigen Problemen der Ockhamforschung,” in Archivum Franciscanum historicum, 46 (1953), 181–194; “Handschriftliches zu Wilhelm Ockham und Walter Burley,” ibid., 48 (1955), 234–251; “Ein unbeachteter ’Averroist’ des XIV Jahrhunderts: Walter Burley,” in Medioevo e rinascimento: Studi in onore di Bruno Nardi (Florence, 1955), 477–499; “Zu Walter Burleys Traktat De intensione et remissione formarum,” in Franciscan Studies, 25 (1965), 293–321. Maier has included these articles (save the last), together with addenda, in her Ausgehendes Mittelalter: Gesammelte Aufsätze zur Geistesgeschichte des 14. Jahrhunderts, 2 vols. (Rome, 1964–1967).

See also L. Baudry, “Les rapports des Guillaume d’Occam et de Walter Burleigh,” in Archives d’histoire doctrinale et litteraire du moyen age, 9 (1934), 155–173: A. Koyré, “Le vide et 1’espace infini au XIV^e siecle,” ibid., 17 (1949), 75–80; three articles of S. H. Thomson, “Walter Burley’s Commentary on the Politics of Aristotle,” in Melanges Auguste Pelzer (Louvain, 1947), pp. 557–579; “An Unnoticed Questio theologica of Walter Burley,” in Medievalia et humanistica, 6 (1950), 84–88: “Unnoticed questiones of Walter Burley on the Physics, “in Mitteilungen des Instituts für österreichische Geschichtsforschung, 62 (1954), 390–405: four articles by H. Shapiro, “Walter Burley and Text F 1,” (i.e., of Book IV of the Physics), in Traditio, 16 (1960), 395–404; “Walter Burley and the Intension and Remission of Forms,” in Speculum, 34 (1959), 413–427 in conjunction with Anneliese Maier on the same topic); “A Note on Walter Burley’s Exaggerated Realism.” in Franciscan Studies, 20 (1960), 205–214; “More on the ‘Exaggeration’ of Burley’s Realism,” in Manuscripta, 6 (1962), 94–98.

A brief treatment of Burley’s view on first and last instants, together with other late Scholastic discussion of the same problem, may be found in Curtis Wilson, William Hevtesburv: Medieval Logic and the Rise of Mathematical: Physics (Madison, Wis., 1956), pp. 29–56.

John Murdoch

Edith Sylla

BURLEY, WALTER

b. England, c. 1275; d. c. 1345),

logic, natural philosophy. For the original article on Burley see DSB, vol. 2.

Although Burley obtained his doctorate in theology from the University of Paris in the mid-1320s, and although he held numerous church livings, as well as serving both the English king and Richard de Bury, Bishop of Durham, he is unusual, among fourteenth-century

scholars, for having continued to be active in natural philosophy and logic until his death, some time after 1344. Since he also began producing works on the subjects of the Faculty of Arts at Oxford as early as 1300, this means he had a career in philosophy of more than forty years.

Commentaries on Aristotle. Burley’s commentaries on Aristotle’s Physics may be taken as representative. His first commentary on the Physics, in the form of expositions of the text alternating with relatively long questions, is extant in MS Cambridge, Gonville and Caius 448/409. It most likely resulted from his teaching at Oxford before leaving for Paris to study theology, some time before 1310 and possibly as early as 1307. Besides this earliest work, which may be referred to as his Expositio cum quaestionibus on the Physics, there are several manuscripts that contain only Quaestiones on the Physics by Burley (and these only for certain books), without accompanying expositions. Although scholars have considered this a second work by Burley on the Physics, it is probably more accurate to understand it consisting of selected questions from the Expositio cum quaestionibus apart from the related expositions. And, finally, there is Burley’s Expositio in libros octo de phisico auditu, compiled when he was in Paris and even later in the employ of Richard de Bury back in England, which was printed eleven times between 1476 and 1609. Book IV of this version, which includes revised versions of significant sections of Burley’s Oxford Expositio cum quaestionibus, was finished at Paris in 1326. Books VII and VIII were revised ten years later, between 1334 and 1337, at the suggestion of Richard de Bury. In this final Expositio Burley on numerous occasions defends his views against the novel theories of William of Ockham. So, for instance, in response to Ockham, Burley inserted a long defense of the existence of indivisibles such as instants of time or geometric points into Book I of the final Expositio, something he had not thought it necessary to do in earlier versions, before Ockham and other ontological minimalists denied their reality.

Although much work has been done on Walter Burley since the original DSB article, he was so prolific, and his ideas may have developed from one period of his life to the next to such an extent, that it is still difficult to see his contribution as a whole and to place it within its fourteenth-century context, either at Oxford or on the Continent, where he is known to have lectured or disputed not only at Paris, but also at Toulouse and Bologna. In 1978 Agustin Uña Juarez published a large book devoted to Burley (see bibliography below). Uña Juarez discusses, for instance, Burley’s relationships to Averroës, on the one hand, and to Ockham, on the other—both issues that scholars have continued to take up.

Relationship to Wylton. An issue yet to be resolved is Burley’s relationship to Thomas Wylton. From remarks in Burley’s Tractatus Primus, which derives from the principia or initial lectures on Peter Lombard’s Sentences that Burley gave as a bachelor of the Sentences at Paris, it is probably safely concluded that it was Thomas Wylton who oversaw Burley’s work in theology at Paris. But Wylton and Burley were also near contemporaries at Merton College in Oxford, and there are many passages in their works, such as their questions on Aristotle’s Physics, that are so close as to be almost identical. Although this has been noticed, the explanation is unclear. Might Burley have first heard Wylton lecture on the Physics and then made use of Wylton’s lectures when he came to teach the Physics himself? Would the source of the similarities have come from the men hearing each other lecture and dispute, or might one have had the manuscript of the other on hand while writing his own? At Burley’s principium on Book IV of the Sentences at Paris, Wylton was very clearly in the room, raising objections orally. Was there also a live connection at Oxford? So far this remains an open question.

Relationship to Ockham. In the case of individuals from earlier times, such as Averroës, Thomas Aquinas, and Robert Grosseteste, Burley very clearly had manuscripts of each man’s work in front of him as he wrote his own commentaries. He copied their opinions so exactly that his commentaries have been used in establishing editions of the others’ works. The communication between Burley and Ockham is unclear, particularly if Ockham is supposed to have been living in the Franciscan house of studies in London for some time, where Burley, as a secular, would presumably not have been present. It has already been noted above that Burley reacted to Ockham’s ontological parsimony in composing his final Expositio on the Physics. Did Burley become familiar with Ockham’s views through Ockham’s logical and natural philosophical works, or was he reacting to things that Ockham propounded in his commentary on the Sentences? In editing Ockham’s Quaestiones on the Physics, Stephen Brown noted that several of Ockham’s questions make wholesale use of Burley’s Tractatus Primus(related to Burley’s commentary on the Sentences) both in formulating questions and in proposing responses. Ockham comes sometimes to the same conclusion as Burley and sometimes to the opposing solution. There is little doubt in this case that Ockham was working from a manuscript of Burley’s Tractatus Primus, so it is not necessary to conclude that Burley was involved in person in this transfer of ideas.

Ideas about Qualities. In his De causis mirabilium, Nicole d’Oresme cited Burley’s opinion that contraries like hot and cold, white and black, and so forth belong to the same species—an opinion that Burley had argued for in his Tractatus Primus— no doubt distantly related at least to the qualities in the Eucharist, since the Tractatus Primus derived from Burley’s principium on Book IV of Peter Lombard’s Sentences. Oresme connected Burley’s views on hot and cold and other qualities to the subjectivity of sensation—that what seems hot to one person may feel cold to another. Burley’s influence on later authors seems to have derived primarily from the clarity and thoroughness of his writing, both in logic and in natural philosophy. His positions were established before William of Ockham electrified his contemporaries with his so-called nominalism or ontological minimalism. Although Burley is often characterized as Ockham’s realist opponent, there are many similarities between the physical views of Burley and Ockham, particularly to the extent that both Burley and Ockham were influenced by the ideas of John Duns Scotus. The originality of the theory of beginning and ceasing expounded in Burley’s De primo et ultimo instanti is becoming clearer to historians as it is realized that, unlike Burley, Peter of Spain in his earlier theory held that there is a last instant of permanent beings (this had been obscured because a fifteenth-century revision of Peter of Spain’s Tractatus syncategorematum revised it along the lines of Burley’s theory).

Burley’s Logic. A great deal of the scholarship concerning Burley’s work that has been done in recent decades concerns his logic, rather than his natural philosophy. Thus scholars have been interested in Burley’s formulation of the logical exercise called “obligations,” participation in which was required of late medieval university students. Although logic may normally be considered to fall outside the realm of “science,” it would be a mistake to exclude contributions to logic from the history of medieval science, given that logic was as much the instrument of late medieval science as mathematics was to become the instrument of science par excellence in later periods. In the supplementary bibliography that follows are included a sample of recent articles on Burley’s logical work. In his commentary on Aristotle’s Posterior Analytics, and on Book I of the Physics, Burley argues that natural knowledge first derives from experience, following the pattern made famous by Robert Grosseteste of distinguishing knowledge of facts (quia) from knowledge of their causes (propter quid).

Institutional Context. As far as the institutional context of Walter Burley’s work is concerned, his work first in the faculty of arts at Oxford and then in the faculty of theology at Paris falls into expected patterns. More intriguing is his continued participation, orally and in writing, in philosophical concerns after leaving the University of Paris about 1327. In part, Burley’s continued scholarly activity may be ascribed to his having been a member of the group of clerks with whom Richard de Bury surrounded himself, a group that included at different times Thomas Bradwar-dine, Richard Kilvington, and others. As Burley carried out diplomatic missions for Richard de Bury and for the king, he seems to have had occasion to communicate with other scholars—sometimes, perhaps, at the papal court in Avignon. Burley’s peregrinations to Bologna and elsewhere, and the dedications of the revised versions of his works to Richard de Bury, found in several manuscripts, reveal a pattern of lifelong learning on the part of individuals outside universities or other educational institutions.

SUPPLEMENTARY BIBLIOGRAPHY

WORKS BY BURLEY

Obligationes. Introduction to the Logical Treatise ‘De Obligationibus’: with Critical Texts of William of Sherwood (?) and Walter Burley. Edited by Romuald Green. Louvain, Belgium: Université catholique, Institut Supérieur de Philosophie, 1963. Partial translation in Logic and Philosophy of Language. The Cambridge Translations of Medieval Philosophical Texts, vol. 1, edited by Norman Kretzmann and Eleonore Stump, 370–412. Cambridge, U.K., and New York: Cambridge University Press, 1988.

Insolubilia. Edited by Marie Louise Roure. “La Problématique des propositions insolubiles au XIIIe siècle et au début de XIVe, suivie de l’édition des traités de W. Shyreswood, W. Burley and Th. Bradwardine.” Archives d’histoire doctrinale et littéraire du moyen âge37 (1970): 262–284.

Tractatus de formis. Edited by Frederick J. D. Scott. Veröffentlichungen der Kommission für die Herausgabe ungedruckter Texte aus der mittelalterlichen Geisteswelt, Bd. 4. Munich, Germany: Verlag der Bayerischen Akademie der Wissenschaften, 1970.

Tractatus de suppositionibus. Edited by Stephen Brown. In “Walter Burleigh’s Treatise De suppositionibus and Its influence on William of Ockham.” Franciscan Studies 32 (1972): 15–64.

“Middle Commentary” on the Perihermeneias. Edited by Stephen Brown. “Walter Burley’s Middle Commentary on Aristotle’s Perihermeneias.” Franciscan Studies33 (1973): 42–134.

Quaestiones in Librum Perihermeneias. Edited by Stephen Brown.Franciscan Studies34 (1974): 200–295.

De exclusivis. Edited by Lambertus M. de Rijk. In “Walter Burley’s Tract De exclusivis: An Edition.” Vivarium23 (1985): 23–54.

De exceptivis. Edited by Lambertus M. de Rijk. In “Walter Burley’s De exceptivis, an Edition.” Vivarium24 (1986): 22–49.

Utrum contradictio sit maxima oppositio. Edited by Lambertus M. de Rijk. In “Burley’s So-Called ‘Tractatus Primus,’ with an edition of the additional questio ‘Utrum contradictio sit maxima oppositio.’” Vivarium34 (1996): 161–191.

With Adam Burley. Questions on the De anima of Aristotle. Edited by Edward A. Synan. Leiden, Netherlands, and New York: E.J. Brill, 1997. Krieger (see below) lists this as a doubtful or spurious work.

On the Purity of the Art of Logic: The Shorter and the Longer Treatises. Translated by Paul Vincent Spade. New Haven, CT: Yale University Press, 2000.

Quaestiones super librum Posteriorum. Edited by Mary Catherine Sommers. Studies and Texts 136. Toronto: Pontifical Institute of Mediaeval Studies, 2000.

OTHER SOURCES

Brown, Stephen. Notes. In Guillelmi de Ockham, Brevis Summa Libri Physicorum; Summula Philosophiae Naturalis, et Quaestiones in libros Physicorum Aristoteles. Opera Philosophica VI. St. Bonaventure, NY: St. Bonaventure University Press, 1984. 41ff. and 773ff. Notices Ockham’s use of Burley’s Tractatus Primus in his Quaestiones in libros Physicorum. If Ockham’s Quaestiones date from 1323–1324, then the Tractatus Primus must have been available before that date.

Caroti, Stefano. “Da Walter Burley al ‘Tractatus sex inconvenientium’: la tradizioine inglese della discussione medievale ‘De reactione.’” Medioevo21 (1995): 257–374.

Dutilh Novaes, Catarina. “Medieval Obligationes as Logical Games of Consistency Maintenance.” Synthese145 (2005): 371–395. In the first section, surveys modern interpretations of the purposes of obligationes as university exercises, focusing on Walter Burley’s treatise, and concluding with a bibliography of recent studies on obligationes.

Feltrin, Paola. “Il problema del primo e ultimo istante in Walter Burley.” Medioevo9 (1983): 137–178.

Grignaschi, Mario. “Lo pseudo Walter Burley e il ‘Liber de vita et moribus philosophorum.’” Medioevo16 (1990): 131–190. Calls Burley’s authorship of the Liber de vita et moribus philosophorum into question.

Kretzmann, Norman, Anthony Kenny, and Jan Pinborg, eds. The Cambridge History of Later Medieval Philosophy. Cambridge, U.K.: Cambridge University Press, 1982. Covers the work of Walter Burley in many sections (see index under Walter Burley).

Krieger, Gerhard. “Studies on Walter Burley, 1989–1997.” Vivarium37 (1999): 94–100.

Lagerlund, Henrik, and Erik J. Olsson. “Disputation and Change of Belief—Burley’s Theory of Obligationes as a Theory of Belief Revision.” In Medieval Formal Logic: Obligations, Insolubles and Consequences, edited by Mikko Yrjönsuuri. Dordrecht, Netherlands, and Boston: Kluwer, 2001. An example of how Burley’s views on logic are taken seriously, although the article involves modern theories of belief change as much as Burley’s work on obligationes.

Lohr, Charles. “Medieval Latin Aristotle Commentaries.” Traditio24 (1968): 179–180. List of Burley’s commentaries. Ottman, Jennifer, and Rega Wood. “Walter Burley: His Life and Works.” Vivarium37 (1999): 1–23. This is the lead article in a volume also containing papers by Elizabeth Karger, Paul Vincent Spade, Risto Saarinen, Rega Wood, and Gerhard Krieger on Burley. Two of these articles are on logic and two others are on ethics.

Spade, Paul. “Three Theories of Obligationes: Burley, Kilvington and Swyneshed on Counterfactual Reasoning.” History and Philosophy of Logic3 (1982): 1–32.

———. “If Obligationes Were Counterfactuals.” Philosophical Topics20 (1992): 171–188. Retracts the theory of obligations as counterfactuals that he espoused in his 1982 article. ———. “How to Start and Stop: Walter Burley on the Instant of Transition.” Journal of Philosophical Research19 (1994): 193–221.

Stump, Eleonore. “The Logic of Disputation in Walter Burley’s Treatise on Obligations.” Synthese63 (1985): 355–374.

Sylla, Edith Dudley. “The A Posteriori Foundations of Natural Science. Some Commentaries on Aristotle’s Physics, Book I, Chapters 1 and 2.” Synthese40 (1979): 147–187. See pages 169–176 for Burley’s commentaries and their relations to those of Thomas of Wylton and William of Ockham, as well as to the earlier commentaries of Averroës, Thomas Aquinas, and Robert Grosseteste.

_______. “Walter Burley’s Tractatus Primus: Evidence concerning the Relations of Disputations and Written Works.” Franciscan Studies 44 (1984): 257–174.

_______.The Oxford Calculators and the Mathematics of Motion, 1320–1350. Physics and Measurement by Latitudes. New York and London: Garland, 1991. Contains outlines of Burley’s Tractatus Primus and Tractatus Secundus, as well as a discussion of his theory of latitudes and degrees.

_______. “Walter Burley’s Physics Commentaries and the Mathematics of Alteration.” Early Science and Medicine 6 (2001): 149–184.

_______. “Walter Burley’s Practice as a Commentator on Aristotle’s Physics,” Medioevo27 (2002): 301–372.

_______. “The Status of Astronomy between Experience and Demonstration in the Commentaries on Aristotle’s Posterior Analytics of Robert Grosseteste and Walter Burley.” In Erfahrung und Beweis: Die Wissenschaften von der Natur im 13. und 14. Jahrhundert, edited by Alexander Fiodora and Matthias Lutz-Bachmann. Berlin: Akademie Verlag, 2007.

Trifogli, Cecilia. “The Reality of Time in the Commentary Tradition on the Physics: The Case of Wylton and Burley.” In Il Commento Filosofico nell’Occidente Latino, Secoli XIII–XV, edited by Bianfranco Fioravanti, Claudio Leonardi, and Stefano Perfetti, 233–252. Turnhout, Belgium: Brepols, 2002.

Uña Juarez, Agustin. La Filosofia del Siglo XIV. Contexto Cultural de Walter Burley. Madrid: Biblioteca “La cuidad de Dios” Real Monasterio de el Escorial, 1978.

Weisheipl, James. “Repertorium Mertonense.” Mediaeval Studies31 (1969): 185–208.

Wood, Rega. “Walter Burley’s Physics Commentaries.”Franciscan Studies44 (1984): 275–327. Burley’s earliest Physics commentary, consisting of an exposition and questions, which Wood labels the “pre-1316 commentary,” was probably written before Burley left Oxford for Paris, perhaps as early as Easter 1307 and in any case by 1310. From this earliest commentary are derived many if not all of the questions in Burley’s separate Questiones super libros Physicorum, which Wood tentatively dates before 1322. Thus the separate questions might also have been completed at Oxford before 1310 or even 1307.

_______. “Studies on Walter Burley, 1968–1988.” Bulletin de Philosophie Médiévale30 (1988): 233–250.

_______. “Walter Burley on Motion in a Vacuum.” Traditio45 (1989–1990): 191–217.

Edith Dudley Sylla