We use cookies to ensure that we give you the best experience on our website. You can change your cookie settings at any time. Otherwise, we'll assume you're OK to continue.

Durham University

Institute of Medieval and Early Modern Studies (IMEMS)


The list below shows Durham University research staff who are members of IMEMS. Click the member's name to see a more detailed biography and department.

We also welcome anyone from outside the University with an interest in our work to join. Membership is free of charge. You will receive invitations to our programme of events, with a weekly emails digest about what is happening in the Insitute and further afield. To join IMEMS contact:

Publication details for Dr Sara L. Uckelman

Uckelman, Sara L. (2015). Sit Verum Obligationes and Counterfactual Reasoning. Vivarium 53(1): 90-113.

Author(s) from Durham


In the early 1980s, Paul V. Spade advanced the thesis that obligational reasoning was counterfactual reasoning, based upon his interpretation of the obligationes of Walter Burley, Richard Kilvington, and Roger Swyneshed. Eleonore Stump in a series of contemporary papers argued against Spade’s thesis with respect to Burley and Swyneshed, provisionally admitting it for Kilvington with the caveat that Kilvington’s theory is by no means clear or non-idiosyncratic. In this paper, we revisit the connection between counterfactual reasoning and obligationes, focusing on one particular treatise, the anonymous early twelfth-century Obligationes Parisienses edited by L.M. de Rijk in the late 70s. We show that while positio in this treatise does not involve counterfactual reasoning, the species sit verum or rei veritas apparently does, and it is precisely this which distinguishes the two species in this treatise.