Handbook of the History of Logic: - Fordham University Faculty

The Development of Supposition Theory in the Later 12 th through 14 th Centuries 233
The significance of suppositional mode being local will emerge when we discuss
rules of inference below, and when in the next section we contrast the early theory
with the later, in which modes of supposition are global, not local.
7.5 Causes of Distribution and Confusion
All scholars agree that neither confusion nor distribution can occur unless it is
caused to occur. Generally, it was thought that they must be caused to occur by
some sign which has scope over the term in question. 90 We look here at some 13 th
century accounts.
Confusion and distribution need to be caused, but determinacy does not; this is
because a common term that is unaffected by any sign is determinate by default.
It is also immobile by default. Its status can be changed by the addition of some
sign, though not just any old sign; a particular sign such as ‘some’ leaves its
determinate status unchanged.
Signs other than particular ones can affect
Confusion ...causing it or undoing it,
Distribution ...causing it or undoing it,
Mobility ...causing it or undoing it.
For example, ‘every’ in the universal affirmative form confuses and distributes and
makes mobile the subject to which it is adjoined; it confuses the predicate without
distributing it and without making it mobile. The ‘no’ in the universal negative
confuses and distributes both the subject term to which it is adjoined and the
predicate term, and makes them both mobile.
Sherwood gives three rules for confusion and distribution [IL V.13.1 (117).]
(The rules presuppose that a term starts out determinate by default.):
[A] every distributive sign confuses the term immediately adjoining it
confusedly and distributively.
[B] an affirmative [distributive] sign confuses the remote term merely
confusedly.
[C] a negative [distributive] sign confuses the remote term confusedly
and distributively.
Thus this follows: ‘nomanisanass;thereforenomanisthisass’. But
this does not follow: ‘every man is an animal; therefore every man is
this animal’.
Sherwood’s rules say nothing about mobility, which is what is at issue in the
examples he gives. (The question is whether one may descend under ‘ass’ or
‘animal’.) I think that he is presupposing a rule about mobility, which I will call
D:
90The notion of scope here is a modern one; I use it here to sum up what seems to me to be
the medieval practices. Certain writers thought that confusion or distribution could be caused
without a sign, by the will of the speaker (such as giving distributive supposition to the subject
of an indefinite proposition such as ‘A donkey is an animal’). Cf. [Barney et al., 1997].