>>Dr. Kerry Magruder: Thanks for joining me
in the History of Science Collections of the
University of Oklahoma Libraries. Let's look
at a couple treasures from the vault that
throw light on the story of science in the
14th century. This book contains lectures
by John Duns Scotus, delivered in Oxford in
1302, printed much later in 1481. The rear
wooden board bears a brand, burned into the
surface, to identify it as belonging to the
library of the Franciscans of Villengen, near
Strassburg. It contains extensive annotations.
Scotus, along with other 14th century theologians
and philosophers such as William Ockham, Jean
Buridan, and Nicole Oresme, mounted a sustained
critique of Thomas Aquinas' synthesis of science
and faith, arguing that divine omnipotence
required the created order to be contingent,
and therefore not completely transparent to
rational demonstration. Pierre Duhem in these
many volumes, and numerous more recent scholars
have shown that, if nature is contingent,
that is, if it might have been made otherwise
than it is, then Aristotle's logic, physics
and cosmology would all have to be greatly
revised to allow more than one possible outcome.
In the hands of 14th-century writers like
these, a critique of rational necessity led
to such ideas as the possible existence of
other worlds, a rotating Earth, and an Earth
characterized not by eternity but by a very
ancient history that might be reconstructed
on the basis of empirical fossil evidence.
One expression of this 14th-century critique
of rational necessity was an increasing role
for experiment. If nature is contingent, then
experimental methodologies will be essential
to grasp the natural order. An example of
a 14th-century experimental tradition is the
investigation into the optics of the rainbow
by the monk Theodoric of Freiberg. Theodoric
experimented with spherical flasks filled
with water. Each flask modeled an individual
raindrop in a cloud, with the sunlight shining
on them from a crack in the ceiling. He observed
that different colors appeared as he would
raise the flask higher or lower. By covering
certain portions of the flask at a time, one
after another, to see where the light would
come out, Theodoric determined the path that
light follows from the Sun as it passes through
the drop to the human eye to create a rainbow.
Theodoric's explanation of the primary and
secondary rainbow as a result of refraction
and reflection is still regarded as correct.
That is, the paths traced by the rays of light
through raindrops to produce both the primary
and secondary rainbows was confirmed by Descartes
in the 17th century, as printed in this work
of Descartes. For this reason, Theodoric of
Freiberg's discovery of the optics of the
rainbow is often regarded as a triumph of
experimental methodology in the late Middle
Ages. Science is a story. What stories do
you want to hear and tell about 14th-century
science?
