Handbook of the History of Logic: - Fordham University Faculty

Logic in the 14 th Century after Ockham 457
Thomas of Cleves’s ‘fourth’ mode of personal supposition, but to him this is not
a fourth but rather a third mode, because he does not recognize merely confused
personal supposition. While this may seem an awkward position at first sight, it
is not altogether implausible considering that, for Vincent Ferrer, and following
very early (12 th and 13 th century) notions of supposition, it is only the subject of
a categorical proposition that has supposition, not the predicate (cf. [Trentman,
1977, 89-92]). Given that, usually, merely confused personal supposition concerns
the supposition of the predicate (in particular in universal affirmative propositions),
if one does not attribute supposition to the predicate, then there may seem
to be no need to recognize merely confused personal supposition.
But the fact that Ferrer recognized collective supposition poses a historiographic
problem. While there is a clear line of continuity between the other authors mentioned
so far (Maulfelt, Albert of Saxony, Thomas of Cleves, all roughly belonging
to the same Parisian nominalist tradition), Vincent Ferrer was, as already mentioned,
educated in Spain, and saw himself as belonging to a Thomist tradition,
thus completely out of the circle of influence of the nominalist tradition. Read
[1991a, 74] argues that Ferrer’s treatise ‘does not read like that of an author inventing
an original theory’; that is, presumably collective supposition was already
a recognized mode of supposition in the tradition within which he was schooled.
We could thus have two independent ‘inventions’ of the concept of collective supposition.
But our knowledge of the 14 th century Spanish logical tradition is as of
yet still insufficient in order to tell us whether the concept of collective supposition
was indeed independently developed within this tradition (which seems unlikely,
given the coincidence in terminology), or whether there were earlier points of contact
between the two traditions in such a way that there might have been influence
in one direction or in the other (or both).
In sum, the debate concerning nominal conjunctive descent and a fourth mode
of supposition was a heated one in the second half of the 14 th century. While it is
fair to say that the majority of the authors preferred to maintain the traditional
scheme with three modes of common personal supposition (see [Ashworth, 1978]),
for the sake of theoretical parsimony and probably also out of respect for the tradition,
many authors nevertheless recognized the fourth kind of descent. But all
in all, considered from a systematic point of view, it seems that supposition theory
containing four modes of personal supposition is indeed a more sophisticated
version of the traditional theory: it respects the logical symmetry of nominal and
propositional descent, and it allows for a very intuitive account of the semantics
of some terms (even if some of them can also be accounted for with only the three
traditional kinds of descent).
2.1.3 Different modes of supposition also for material supposition
In the traditional formulations of theories of supposition, in particular with the
13 th century summulists (William of Sherwood, Peter of Spain), but also with
authors of the first half of the 14 th century such as Ockham and Buridan, there