ABSTRACT
Robert Kilwardby discusses an apparent counter-example to Aristotle's laws of modal conversion. Kilwardby states that abstract terms are understood differently depending on whether they occur in subject- or predicate-position: in subject-position they stand for their supposita, in predicate-position for a quality or form. Like Averroes, Kilwardby draws a distinction between substantial and accidental terms, counting among the former 'man', 'animal' and 'ass'; among the latter 'white', 'black' and 'literate'; and his 'substantial' terms seem to correspond exactly with Averroes's per se terms. Also like Averroes, Kilwardby uses the expression 'per se necessity'. In Averroes this refers to de dicto inclusions or exclusions with per se subject and predicate; and it appears to have the same meaning in Kilwardby. Kilwardby follows Alexander's interpretive strategy whereby, in the case of pure contingency-syllogisms, both conclusion and premises are to be read as being ampliated, but in the case of mixed contingency-syllogisms this is not the case.
