Handbook of the History of Logic: - Fordham University Faculty

Medieval Modal Theories and Modal Logic 561
knowledge in Ockham is considered an act of judicative belief, Ockham’s concept
of knowledge could be regarded as implying the principle
(21) Kap → Bap.
Robert Holcot explicitly treated assent as a belief, pointing out that the most
common sense of believing (credere) is to assent to what is stated by a proposition.
‘A proposition is believed when it is assented to, and in this way we believe what
we know as well as what we formally opine.’ 220 Ockham remarks that the term
‘knowledge’ is sometimes applied to firm cognition of a truth, but he considered
this use less proper than those which included a reference to evidence as some kind
of justification. Instead of the definition
he prefers
Kap = Bap & p
Kap = Bap & p & Jap.
(Jap stands for ‘the person a is justified in believing that p’.) 221 As shown by
Ivan Boh, some later authors were reluctant to accept the first use of knowledge.
Their reasons were similar to those which have been presented in the contemporary
discussion of the Gettier problem. 222 Some authors were interested in the question
of the role of the will in assenting to a proposition. It was usually thought that
evident assent was caused naturally and that there were types of non-evident assent
which were freely caused, such as the religious assent of faith or the opinative
assent based on probabilistic arguments. Robert Holcot argued that beliefs were
not freely chosen, but this view was considered over-stated. 223
The theory of free assent was sometimes associated with the question of making
moral decisions in uncertain cases, which anticipated the later controversy over
Bonaventure University, 1967), prol. 1, 16.3-18. For the distinction between apprehensive and
judicative acts in late medieval and early modern thought, see K. Tachau, Vision and Certitude
in the Age of Ockcham: Optics, Epistemology and the Foundations of Semantics 1250-1345 (Leiden:
Brill, 1988), 117-18; A. Broadie, Notion and Object: Aspects of Late Medieval Epistemology
(Oxford: Clarendon Press, 1989), 125-48.
220 Robert Holcot, In quatuor libros Sententiarum quaestiones (Lyon, 1518, reprinted Frankfurt
am Main: Minerva, 1967), I.1.6.
221 See William Ockham, Expositio in libros Physicorum Aristotelis, prol. et libri I-III, ed. V.
Richter and G. Leipold, Opera philosophica 4 (St. Bonaventure: Franciscan Institute of St.
Bonaventure University, 1985), prol. 5.29-6.50.
222 Boh refers to a passage from Peter of Mantua’s Logica which shows that a person could be
said to know (in the first sense of ‘scire’) that p even when the assent is based on a mistake: ‘Let
it be posited that Plato is very near you and you know that he is running, but you believe that
he is Socrates so that you firmly believe that Socrates is running. But let Socrates in fact be
running in Rome, although you do not know this. You thus know that Socrates is running and
do not know that Socrates is running, therefore, on the same basis, what is known is doubtful to
you’ (Logica 17rb, translated in Boh, 2000, 136).
223 See Holcot, Sent. I.1.1; Holcot’s view is criticized, e.g., in Peter of Ailly, Questiones super
libros Sententiarum (Paris 1500), princ. III, I D, 1.2 BB. For the discussion of this question in
Paris between 1500 and 1530, see Broadie 1989, 149-78.