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Modal Logic in the Middle Ages
Research Project: Models, Modality and Meaning
22nd November 2012 - 23rd November 2012
All those interested are welcome to attend, but registration is necessary for attendance. Registration is free, and includes lunch, tea and coffee. Please register by Thursday 15 November.
Thursday 22 November:
9.45 Welcome by Stephen Read
10.00 Wilfrid Hodges (formerly, Queen Mary London): Permanent and necessary in Ibn Sina
11.15 Tea and Coffee
11.45 Saloua Chatti (Tunis): Existential import in Avicenna’s modal logic
2.00 Visit to MUSA (Museum of the University of St Andrews), introduced by the University Archivist, Dr Norman Reid
3.15 Tony Street (Cambridge): On translating Katibi’s Epistle for Shams al-Din on the Rules of Logic
4.30 Tea and Coffee
5.00 Sara Uckelman (Tilburg): Epistemic and higher-order modalities in Obligationes
7.30 Dinner at the Adamson
Friday 23 November:
10.00 Paul Thom (Sydney): The early reception of Robert Kilwardby’s modal syllogistic
11.15 Tea and Coffee
11.45 Catarina Dutilh Novaes (Groningen): Ockham and Buridan on the semantics of divided modal propositions
2.00 Spencer Johnston (St Andrews): John Buridan’s divided modal syllogistic
3.15 Stephen Read (St Andrews): Non-Contingency syllogisms in Buridan’s Treatise on Consequences
4.30 Tea and Coffee
5.00 Riccardo Strobino (Bochum and Cambridge): Having one without the other: inseparability and logical consequence
Saloua Chatti: Existential import in Avicenna’s modal logic
In this paper, I raise the following problem: What propositions have an existential import in Avicenna’s modal theory? Which ones do not? Starting from the assumption that a proposition has an import if it cannot be true in case the subject’s referent is non-existent, I briefly discuss the import of absolute (that is, assertoric) propositions, then I analyze the import of the modal propositions, whether their modalities are external or internal, by taking into account Avicenna’s definitions of necessity and possibility and the relations between modal propositions. These relations help determine the import of the negative propositions, once that of the affirmatives is settled. But Avicenna’s theory is not so clear, for while the necessary affirmative propositions seem to have an import, the case of possible propositions is more obscure and depends on the kind of possibility considered.
Catarina Dutilh Novaes: Ockham and Buridan on the semantics of divided modal propositions
Divided modal propositions are those where the modality occurs as an adverb modifying the copula, such as ‘A man is necessarily an animal’. They contrast with composite modal propositions, where the modality is predicated of a whole proposition in nominalized form, e.g. ‘That a man is an animal is necessary’. Both William of Ockham and John Buridan discuss extensively the semantics of the two kinds of modal propositions, and at first sight it may seem that they ascribe similar semantic properties to divided modal propositions. However, while Ockham maintains that the modal term only affects the supposition of the predicate, for Buridan a proposition such as ‘A man is necessarily an animal’ is equivalent to ‘That which is or can be a man is necessarily an animal’. In other words, for Buridan the subject of a divided modal proposition behaves like a term disjunction. This has a number of interesting consequences for the logical properties of such proposition, which Buridan investigates in Book II of his Treatise on Consequences.
Wilfrid Hodges: Permanent and necessary in Ibn Sina
In various places Ibn Sina makes what to all appearances are highly incompatible statements about the relationship between permanent and necessary. We offer a resolution. It rests on an examination of Ibn Sina’s probable sources going back to Theophrastus, and Ibn Sina’s own explanation of one of these incompatibilities. Ibn Sina emerges as a highly original semanticist who can point out new things even to a modern reader, but the view he presents would serve badly as a basis for a systematic modal logic. (Slides and evidence will be on my website.)
Spencer Johnston: John Buridan’s divided modal syllogistic
John Buridan’s treatment of the modal syllogism is in many ways a departure from Aristotle’s presentation and the commentators who wrote on the Prior Analytics. In this talk I will present a semantic reconstruction of Buridan’s theory for divided propositions based on his Treatise on Consequence. During the talk we will highlight a number of interesting features about Buridan’s theory of modality, in particular the role that ampliation plays.
Stephen Read: Non-Contingency syllogisms in Buridan’s Treatise on Consequences
Whereas his predecessors attempted to make sense of, and if necessary correct, Aristotle’s theory of the modal syllogism, John Buridan starts afresh in his Treatise on Consequences, treating separately of composite and divided modals, then of syllogisms of necessity, possibility, and with mixed premises. Finally, he comes in the penultimate chapter of the treatise, Book IV ch. 3, to present a concise treatment of syllogisms with premises of contingency, that is, two-sided possibility. The previous modal syllogisms had all been taken with an affirmed mode only, since modal conversion equates negated necessity and possibility with affirmed possibility and necessity, respectively. But in his Conclusions concerning syllogisms of contingency, he also treats those with negated mode. These are the non-contingency syllogisms.
Tony Street : On translating Katibi’s Epistle for Shams al-Din on the Rules of Logic
The Shamsiyya has been the most popular Arabic text on logic since the thirteenth century, and was the main source for Rescher’s studies of Arabic modal logic in the 60s and 70s. In this paper, I discuss a number of issues that determine the way Katibi treats modal syllogistic. To do so, I draw on material in the fourteenth-century commentary on the Shamsiyya by Tahtani.
Riccardo Strobino: Having one without the other: inseparability and logical consequence
I shall discuss the relationship between the notions of inseparability and logical consequence from the standpoint of late XIVth century Latin logic. Various characterisations of “following from” will be explored and classified in order to achieve an informal definition of the latitudo of a logical consequence, based on the idea that different modalities may govern the connection between terms occurring in the premisses and the conclusions of a valid inference. The problem will also be discussed with respect to the use of impositio in the context of the theory of obligations.
Paul Thom: The early reception of Robert Kilwardby’s modal syllogistic
Two thirteenth-century anonymous manuscripts (Merton 280, Peterhouse 206) contain treatments of modal syllogistic that generally follow that of Robert Kilwardby’s commentary on the Prior Analytics but differ from it in interesting ways. I trace some lines of Kilwardby’s influence going through these manuscripts and leading to Richard Campsall’s Questions on the Prior Analytics. In comparing these various treatments of the topic, I use a framework based on relations of inseparability and incompatibility between intentiones.
Sara Uckelman: Epistemic and higher-order modalities in Obligationes
Contemporary work on obligationes tends to focus on propositional-level positio. By now, we have a pretty fair grasp of how these types of disputations work on the formal level, and it’s time to move higher. In this talk, I will look at examples of epistemic modalities and higher-order obligations (e.g., disputations about the Respondent’s obligations), and provide first steps to a formal framework that allows for their analysis.