Swyneshed (Swineshead), Roger

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(fl. 1330s; d. 1365 [?]), logic, natural philosophy.

For the original article covering both Roger and Richard Swineshead see DSB, vol. 13.

Roger Swyneshed, fourteenth-century Oxonian, perhaps Benedictine monk and therefore not associated with Merton College, is now known primarily as the author of logical works on the university exercises known as Obligationes and Insolubilia. Also ascribed to him is a work on natural philosophy with sophistical overtones known as Descriptiones motuum or De motibus naturalibus. He is here given his own postscript, rather than being included within the postscript on Richard Swineshead, because there seems little justification for forcing two different people to share a single postscript.

In the years since the DSB was first published, there has been a flowering of research work on medieval logic, and Roger Swyneshed has come into his own as a significant figure within Oxford University in the fourteenth century. In the medieval arts curriculum, logic played the key role that mathematics was later to play as queen and servant of the sciences. Aside from studying the doctrines of logic, undergraduate students were expected to do logic by taking part in oral disputations where correct logical inference and disentangling of fallacies were practiced. In one type of university exercise called obligationes students were asked to accept an initial proposition (the positio), which could well be untrue or counterfactual, and then to accept, reject, or doubt (leave undecided) further propositions depending on whether they were consistent with, contradicted, or were logically irrelevant to the original positio. One set of rules for obligationes at Oxford goes back to the work of Walter Burley at the beginning of the fourteenth century, whereas a new approach was advocated in Swyneshed’s Obligationes, probably written in the 1330s.

In the later fourteenth century such scholars as Robert Fland and Richard Lavenham continued to distinguish between the approach to obligations of Burley and that of Swyneshed. Whereas Burley’s approach required that the respondent in obligations exercises take account not only of the positio but also of all the other propositions subsequently accepted or rejected when deciding what to say to a new proposition, Swyneshed directed the respondent to pay attention only to the positio. Some historians such as Paul Spade have seen obligationes as providing practice in counterfactual reasoning or consistency maintenance; others such as Caterina Dutilh Noveas argue that Swyneshed’s focus was rather on recognizing correct logical inferences.

As would be appropriate for an author steeped in the practice of disputation, the Descriptiones motuum ascribed to Swyneshed defines its terms in such a way as to support conclusions that may seem surprising if not paradoxical, such as that one motion may be infinitely faster or slower than another (Sylla, 1987). Historians have suggested that the frequent use of imaginary cases in fourteenth-century natural philosophy may result from the Condemnations at Paris in 1277, which admonished members of the faculty of arts to admit that God, according to God’s absolute power, might do anything that is not a logical contradiction. In the case of Roger Swyneshed, another motivation for his use of imagination in proposing ways to quantify motions may have been his wish to enable students to defend novel and striking conclusions. Thus it should be understood that the writings now studied from fourteenth-century universities were pedagogical as well as theoretical: they aimed to teach what is now called “critical thinking” as well as the content of the various philosophical disciplines.



Spade, Paul V. “Roger Swyneshed’s Obligationes: Edition and

Comments.” Archives d’histoire doctrinale et littéraire du moyen âge 44 (1977): 243–285.

———. “Roger Swyneshed’s Insolubilia: Edition and

Comments.” Archives d’histoire doctrinale et littéraire du moyen âge 46 (1979): 177–220.


Bottin, Francesco. “The Mertonians’ Metalinguistic Sciences and the Insolubilia.” In The Rise of British Logic, edited by P. Osmund Lewry. Toronto: Pontifical Institute of Medieval Studies, 1985. Treats Roger Swyneshed among the “Mertonians,” although he may never have been associated with Merton College.

Dutilh Noveas, Caterina. “Medieval Obligationes as Logical

Games of Consistency Maintenance.” Synthese145 (2005): 371–395. Focuses on Walter Burley’s treatise on obligationes, to which Roger Swyneshed reacted in his treatise written about thirty years later.

———. “Roger Swyneshed’s Obligationes: A Logical Game of

Inference Recognition?” Synthese 151 (2006): 125–153. Argues that Swyneshed’s theory differs from Burley’s by omitting the dynamic or temporal aspects (the order in which new propositions are introduced). Whereas Burley’s theory emphasizes consistency maintenance, Swyneshed’s is directed toward inference recognition.

Spade, Paul V. “Three Theories of Obligationes: Burley,

Kilvington and Swyneshed on Counterfactual Reasoning.” History and Philosophy of Logic 3 (1982): 1–32. A pioneering interpretation of what is involved the medieval university exercise called obligationes. Dutilh Noveas (above) treats Spade’s hypothesis that it centers on counterfactuals as the strongest competitor to her own.

———. “Medieval Theories of Obligationes.” Stanford

Encyclopedia of Philosophy. First published 14 July 2003. Available from http://plato.stanford.edu/entries/obligationes. Compares the ideas on obligations of Burley and Swyneshed. Ends with an extensive bibliography.

Sylla, Edith D. “The Oxford Calculators and the Mathematics of Motion, 1320–1350. Physics and Measurement by Latitudes.” PhD diss., Harvard University, 1970. Published with a new preface in Harvard University Dissertations in History of Science. New York and London: Garland Press, 1991. Deals with the Descriptiones motuum, including a detailed outline, pp. 543–564.

———. “Mathematical Physics and Imagination in the Work of the Oxford Calculators: Roger Swineshead’s On Natural Motions.” In Mathematics and Its Application to Science and Natural Philosophy in the Middle Ages, edited by Edward Grant and John Murdoch, 69–101. Cambridge, U.K.: Cambridge University Press, 1987.

Edith Dudley Sylla