100 Shank
tion, the unaided human mind could have direct, certain, and evident
knowledge of singular objects. Such views seriously undermined the status
of the universal- oriented demonstrative syllogism as the sole instrument
of scientifi c knowledge; they were, in Marrone’s words, “dynamite for
established Aristotelianism.”^78
The creativity of the fourteenth century also extended logic beyond
Aristotle’s syllogistic to include particular claims derived from experience
and sense perception. It was possible to gain demonstrative knowledge
not simply of universal propositions but also of particular ones. William
of Ockham (d. 1349) discussed a new type of syllogism, the expository
syllogism, designed expressly to produce nonuniversal conclusions. Even
though it has received little attention, “this may well be termed a revolu-
tionary innovation.”^79
Nor did all medieval natural philosophers seek knowledge of the “es-
sential nature” of things. John Buridan (d. after 1358) gave that job to the
metaphysician, not the natural philosopher: “no science besides meta-
physics has to consider the essential nature of a thing ‘simply’... the
physicus need not know what a man is or what an ass is ‘simply’; he may
describe such things by means of some changes or some operations.”^80
Specialization had its advantages. After giving the metaphysician his due,
the natural philosopher could study change without addressing ultimate
reality. It is not a coincidence that Buridan was also the leading logician
of the later Middle Ages, who showed that Aristotle’s syllogistic was in
fact a subset of “consequentiae,” a more general logic of implication (p
implies q) whose variables are not terms but propositions.^81 By the mid-
fourteenth century, medieval natural philosophy had, and used, tools
other than the syllogism.PRACTICE, PRACTITIONERS, AND BOUNDARIES
The emerging universities had enthusiastically embraced the new natu-
ral philosophy, medicine, and (on a smaller scale) the mathematical sci-
ences. Even at Paris, the site of most early opposition to it, Aristotelian
natural philosophy had become a central curricular requirement by the
mid- thirteenth century. To an unprecedented degree, the study of nature
thus acquired a secure home, not in one institution, but in a proliferating
species of institution. As universities multiplied and their enrollments rose
in the fourteenth and fi fteenth centuries, their curricula exposed several
hundred thousand individuals to the study of nature, making it an in-
eradicable part of the European cultural landscape.^82