DUMBLETON, JOHN

(b. England;

d. c. 1349), natural philosophy. For the original article on John Dumbleton (alphabetized under John) see DSB, vol. 7.

Dumbleton’s Summa logicae et philosophiae naturalis(The whole of logic and natural philosophy, about 1340) is a large work found in more than twenty manuscripts, typically large, well-crafted folio volumes. Whereas many of the works of Dumbleton’s Merton College contemporaries, known collectively under the labels the Merton School, or the Oxford Calculatores, received early printed editions, Dumbleton’s Summa did not, probably because of its great length and the fact that it was not used as a textbook, as were Thomas Bradwardine’s Tractatus de Proportionibus(1328; Treatise on proportions), William Heytesbury’s Regulae Solvendi Sophismatum(1335; Rules for solving sophismata), and even Richard Swineshead’s Liber Calculationum (before 1350; Book of calculations). Nevertheless, the Summa is perhaps the best single existing exemplar of fourteenth-century Oxford natural philosophy.

Influences . More is known about the life of John Dumbleton than was known when the original Dictionary of Scientific Biography article about him was written. He is listed at Merton College, Oxford, for 1338 and 1347–1348 and as one of the original fellows of Queen’s College, Oxford, in 1341, but he likely left to study theology in Paris in the early 1340s. As Zenon Kaluza argues, Dumbleton was a fellow of the Sorbonne at about the same time as Étienne Gaudet; that is, perhaps between around 1344 and 1347. Gaudet was the owner or copyist, or both, of several manuscripts that were later owned by Thomas of Cracow around 1400 (and are now at the Bibliothèque Nationale de France in Paris). Manuscript Paris BNF lat. 16621, which was likely copied by Gaudet, contains parts of Dumbleton’s Summa, Bradwardine’s De proportionibus(On proportions), Roger Swineshead’s Descriptiones motuum(Descriptions of motions), and Walter Burley’s De primo et ultimo instanti(On the first and the last instant), as well as works by John Buridan and Nicole Oresme. Two other manuscripts, in the midst of theological questions, refer to “Master John Dumbleton, one time fellow of the Sorbonne, in his Summa. ...” The conclusion they refer to is, indeed, one of Dumbleton’s significant ones, namely that there is no real or imaginary latitude to which all the degrees of perfection may be applied—the reason being that degrees of perfection are indivisible and so do not together compose a continuum.

One “Master Clay,” also from England, was at the Sorbonne at the same time and disputed a question with Dumbleton there. The handsome fourteenth-century copy of Dumbleton’s Summa that is at present-day Paris, Universitaire, MS 599, once belonged to the Oxford University Library and was later in the possession of Thomas Allen and Kenelm Digby, whose notes are found in the margins. In the copy of the Summa now found in Padua, Bibl. Antoniana MS. XVII, 375, f. 21v, Dumbleton is labeled B. Th. at the end of Part I, so it is likely that he completed his theological education at least to the level of bachelor. He seems to have returned to Oxford by 1347–1348, when he is again listed at Merton College, and he probably died in the plague, because nothing is heard of him after 1348.

John of Casali, who was in England as lector at the Franciscan convent in Cambridge in 1341–1342, copied the suppositions of his work, De velocitate motus alterationis(1346; On the velocity of motions of alteration), from Dumbleton’s Summa, and also copied the definitions from Roger Swineshead’s Descriptiones motuum. Casali’s use of triangles to represent the intensity of illumination as it decreases with distance from the light source follows Dumbleton’s approach rather than the later approach of Nicole Oresme. Thus, although Dumbleton did not become as well-known on the Continent as did his fellow Mertonians, Bradwardine and Swineshead (not to mention the earlier Walter Burley), his work was, nevertheless, not without influence. In commenting on Heytesbury’s work on motion in the three categories of place, quality, and quantity, for instance, the Italian Angelus de Fossam-bruno compares the opinion of Dumbleton to those of Bradwardine and Heytesbury.

The Summa logicae et philosophiae naturalis . The contents of the Summa may be seen in the following short outline (each item contains a book within the work:

1. On the significance of terms and their imposition; the relation of definitions to what is defined; on the principles of doctrine and on the intension and remission of hesitation, belief, and knowledge.
2. First principles, matter and form; opinions about substantial forms; how qualities are intended and remitted.
3. On motion in the categories of place, quality, and quantity. On the causes of motion. How velocity is produced and caused. How alteration and augmentation are measured. The definitions of motion and time.
4. On the nature of the elements and their qualities. If each element has two qualities in the highest degree. The action and reaction of elements on each other. The relations of elemental and qualitative forms. Density and rarity and their variation. How the powers of natural bodies depend on their magnitudes. The relative weights of pure and mixed bodies.
5. On spiritual action and light. Whether light belongs particularly to some element or compound. On the nature of the medium receiving spiritual action, such as light. On the variation of spiritual action in a medium. Whether spiritual agents act instantaneously or in time.
6. On the limits of active and passive powers. On the difficulty of action. On the limits of the powers of natural bodies by their natural places. Do the powers of elemental forms seek rest as well as motion? On the motions of the heavens and their movers. On the limits of size of natural bodies. How some bodies are moved by an intrinsic mover (ex se) and some are not.
7. On the cause of individuals and species of generable and corruptible things with regard to their numbers and the potencies of matter and agent. Whether the Prime Mover is of infinite power and whether it has been proved by a physical argument that the world and motion had no beginning.
8. On the generation of substances by like substances and animals by complete animals and by putrefaction. On the numerical unity of the soul with respect to the sensitive and intelligible and on the operations of the nutritive soul.
9. On material related to On the Soul, Book II, concerning the five senses.
10. On universals that are called “Ideas” by the Platonists and on the passive intellect. On the simple and complex operations of the human intellect. (This part may never have been completed, since it is not found in any manuscript.)

Thus, after explaining the fundamental logical approach of medieval natural philosophy in Part I, Dumbleton ranges through metaphysics, physics, the elements and their interactions, optics, biology, and psychology. Parts VIII and IX, on biology and psychology, take up almost 40 percent of the entire work. The basic framework is Aristotelian, but there are some Platonic elements. The topics of most of the parts of the Summa correspond to books by Aristotle that were part of fourteenth-century university curricula, but in many cases Dumbleton alternates between sections discussing typical Aristotelian questions and sections using the analytical tools for which the Oxford Calculators are famous, such as the proportions of velocities in motions, the intension and remission of forms, first and last instants, maxima and minima, and so forth. Dumbleton devotes particular attention to the properties and relations of continua and indivisibles, emphasizing that there is no proportion between a point and a line or between an indivisible degree and a latitude of form. He pairs the latitude of proportion to the latitude of velocity as a way to express Bradwardine’s view of the relation of velocities to the proportions of forces to resistances producing them. Whereas the works of William Heytesbury and Richard Swineshead seem designed to help undergraduate students prepare for disputations, especially disputations on sophismata (ambiguous or paradoxical sounding statements) in the case of Heytesbury, Dumbleton’s Summa more consistently advocates a point of view in natural philosophy, one which includes, upon a foundation of Aristotle, both the nominalism of William of Ockham and the quantification or mathematization associated with Bradwardine’s De proportionibus. It has yet to be established with certainty whether Dumbleton’s Summa was composed before or after Richard Swineshead’s Liber Calculationum. Because the Summa likely was never completed and the Liber Calculationum is found in varying states of completion, perhaps the times of composition of the two works are best seen as overlapping.

SUPPLEMENTARY BIBLIOGRAPHY

The original DSB article cites Weisheipl’s “Repertorium Mertonense,” where he lists manuscripts of the Summa. It also mentions Weisheipl’s edition of a “rather banal” work by Dumbleton in his dissertation. No single library has especially significant unpublished manuscripts of Dumbleton—libraries have at most a manuscript of the Summa. Other than the short work edited in Weisheipl’s dissertation, there are no works of Dumbleton that have been published. The outline in Latin in my dissertation using sentences from the Summa is the closest thing to publication that exists for any of his works.

Caroti, Stefano. “Reactio in English Authors.” In La nouvelle physique du XIVe Siècle, edited by Stefano Caroti and Pierre Souffrin. Biblioteca di Nuncius. Studi e Testi 24. Florence, Italy: Leo S. Olschki, 1997. See pp. 247–248 and note 58 for the relation between Dumbleton and Richard Swineshead on the question of reaction.

Kaluza, Zenon. Thomas de Cracovie: Contribution à l’histoire du collège de la Sorbonne. Wroclaw, Poland: Ossolineum, 1978. This work contains evidence of Dumbleton’s presence at the Sorbonne in the 1340s.

Sylla, Edith Dudley. “Medieval Concepts of the Latitude of Forms: The ‘Oxford Calculators.’” Archives d’histoire doctrinale et littéraire du moyen âge 40 (1973): 223–283.

———. “The Oxford Calculators and Mathematical Physics: John Dumbleton’s Summa Logicae et Philosophiae Naturalis, Parts II and III.” In Physics, Cosmology, and Astronomy, 1300–1700: Tension and Accommodation, edited by Sabetai Unguru. Boston Studies in the Philosophy of Science, vol. 126. Dordrecht, The Netherlands: Kluwer Academic Publishers, 1991.

———. The Oxford Calculators and the Mathematics of Motion, 1320–1350: Physics and Measurement by Latitudes. New York; London: Garland Publishing, 1991. While Dumbleton’s Summa logicae et philosophiae naturalis is still available only in manuscript, a detailed outline of the main sections of Parts II through VI of the Summa is contained in this work.

———. “Imaginary Space: John Dumbleton and Isaac Newton.” In Raum und Raumvorstellungen im Mittelalter, edited by Jan Aertsen and Andreas Speer. Miscellanea Mediaevalia, 25. Berlin: Walter de Gruyter, 1998.

———. “Creation and Nature.” In The Cambridge Companion to Medieval Philosophy, edited by Arthur S. Mcgrade. Cambridge, U.K. and New York: Cambridge University Press, 2003. This article uses an outline of Dumbleton’s Summa as a way to characterize fourteenth-century natural philosophy.

Edith Dudley Sylla