Natural Knowledge in the Latin Middle Ages 93Symptoms of specialization also transpired in genres. The chief format
for inquiry in natural philosophy was the quaestio (“whether local motion
can produce heat,” “whether elements persist formally in a mixed body,”
et cetera).^51 Technical astronomical and optical work was often organized
in treatises, rather than in the “questions” more familiar in natural phi-
losophy and cosmology. Even elementary works in this tradition were
treatises (for example, Sacrobosco’s Tractatus de sphera and Langenstein’s
De reprobatione ecentricorum et epicyclorum).
Masters who practiced natural philosophy, the mathematical sciences,
or medicine typically had a strong sense of their methodological auton-
omy. Their explanatory naturalism therefore did not disappear when they
went on in theology. Already in the twelfth century, Gilbert of Poitiers had
pointed to the different meanings of some words when used in theology
and natural philosophy. In the thirteenth century, both the theologian
Albertus Magnus and the master of arts Siger of Brabant claimed the right
and the duty of ignoring miracles and the faith when they were reasoning
as physici (natural philosophers). John Blund (d. 1248) saw no problem
in disagreeing with saints about the natural world. In matters of faith,
saints were mouthpieces of the Holy Spirit, but in “natural matters” (de
rebus physicis), they spoke as men, and could therefore be deceived.^52 In
the fourteenth century, the theologian Nicole Oresme discussed many
wonders that, he argued, either had or would eventually have physical
explanations: “There is no reason to take recourse to the heavens, the last
refuge of the weak, or to demons, or to our glorious God as if he would
produce these effects directly, more so than those effects whose causes
we believe are well known to us.” Among the learned, the belief in the
natural necessity of secondary causes was wide- ranging, from the use of
mechanical models in astronomy to the striking naturalism of the rabbi
and astronomer Levi ben Gerson, who excluded miracles above the sphere
of the moon when interpreting scripture. Conclusions about the natural
world were cordoned off from miracles by such expressions “according
to physics,” “speaking naturally,” or “according to the light of natural
reason.”^53 The whole point of these activities was to solve problems only
with criteria accessible the senses and the intellect. Only in such an en-
vironment could the arguments of pagans like Aristotle and Ptolemy and
infi dels like Averroës and Ibn al- Haytham command such respect.
The bounds of naturalism were nevertheless contested. At the behest
of conservative theologians, the bishop of Paris’s Condemnation of 1277
took issue, among other things, with the determinism of many proposi-
tions circulating in the arts faculty, as well as with the general uppitiness
of the masters of arts. At stake here and elsewhere was the place of the