Handbook of the History of Logic: - Fordham University Faculty

302 Henrik Lagerlund
Such propositions are assertoric simpliciter, but never necessary per accidens.
According to Averroes, the propositions which are necessary per se have necessary
terms. There are no problems involved in converting such propositions into
necessity propositions. Propositions which are accidentally necessary are not convertible
into necessity propositions. Averroes’ example of a propositions of this
kind is: ‘Every writer is a human being’.
Averroes’ discussion about syllogistic propositions which are necessary per se or
necessary per accidens is much more detailed than what one finds in for example
Robert Kilwardby’s short remarks about the conversion of the necessity premises
(see below). One striking similarity though is that both claim that the subject
term of a necessary proposition per se must not stand for its supposita accidentally.
A proposition is called necessary per se only if both terms are necessary, and it is
called per accidens only if one term is necessary and the other accidental. There
may be necessary connections between the terms of a proposition which do not
fulfil these conditions. The proposition is then not necessary. Accidental necessity
propositions have an accidental term as a subject term and, therefore, there is no
essential connection between the terms as such.
Much more should be said about the logical theories in Arabic logic works
accessible to Latin logicians, but this will have to do for now. These doctrines
were never as influential as Prantl assumed, but neither did they exert no influence
what so ever.
4 THE COMMENTARIES ON ARISTOTLE’S ORGANON
There is an unfortunate lack of edited texts from the early commentaries on Aristotle’s
logic. 52 Albert the Great wrote commentaries on all logic works in the
logica antiquorum and his are the only ones that have been or are being critically
edited. Thomas Aquinas’ logic works has also of course been edited. He only wrote
commentaries on De interpretatione and the Posterior Analytics. One of the most
influential thinkers from this period was, however, Robert Kilwardby. Between
1235 and 1245, he lectured on most of the logica antiquotum and although he was
influenced by Averroes he stands out as a very original thinker. Unfortunately,
none of his commentaries on Aristotle’s logical works have been edited. Albert the
52 There is no chronological catalogue of all the Latin commentaries on the logical works of
Aristotle, but there numerous lists of commentaries available. In [Marenbon, 2000, II, 77–
127], all commentaries before 1150 has been listed, and, in [Marenbon, 2000, VIII, 21–49], all
commentaries on the Categories and De interpretatione before Abelard are listed. In Green-
Pedersen [1984], all commentaries on the Topics are listed. In [de Rijk, 1962] and [Ebbesen,
1981b] many of the early commentaries on Sophistici Elenchi are listed. In [Lohr, 1967; 1968;
1970; 1971; 1972; 1973] and [1974] an alphabetical list of all medieval commentaries on Aristotle’s
logical works can be found. A project in Cambridge run by John Marenbon and Tony Street will
substantially enhance our knowledge of the medieval commentary tradition. In the near future
M. Cameron and J. Marenbon will publish four edited volumes called Aristotelian Logic, East
and West, 500–1500 and with the respective subtitles, the Prior Analytics, the Peri Hermeneias,
the Topics and Methods and Metodolology.