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| Paper: |
Saving the Phenomena in Medieval Astronomy |
| Volume: |
441, The Inspiration of Astronomical Phenomena VI |
| Page: |
519 |
| Authors: |
Seeskin, K. |
| Abstract: |
Aristotle’s theory of motion is based on two principles: (1) all
motion to either from the midpoint of the Earth, toward it, or around
it, and (2) circular motion must proceed around an immovable point.
On this view, the heavenly bodies are individual points of light
carried around by a series of concentric spheres rotating at a
constant pace around the midpoint of the Earth. But even in Aristotle’s day, it was known that this theory had a great deal of difficulty
accounting for planetary motion. Ptolemy’s alternative was to
introduce epicycles and eccentric orbits, thus denying Aristotle's
view of natural motion. There was no doubt that Ptolemy’s predictions
were far better than Aristotle’s. But for the medievals, Aristotle’s
theory made better intuitive sense. Moreover, Ptolemy’s theory raised
the question of how one sphere could pass through another. What to
do? The solution of Moses Maimonides (1138-1204) was to say that it
is not the job of the astronomer to tell us how things actually are
but merely to propose a series of hypotheses that allow us to explain
the relevant data. This view had obvious theological implications.
If astronomy could explain planetary motion in an acceptable way,
there was reason to believe that the order or structure of the heavens
is what it is by necessity. This suggests that God did not exercise
any degree of choice in making it that way. But if astronomy cannot
explain planetary motion, the most reasonable explanation is that we
are dealing with contingent phenomena rather than necessary ones. If
there is contingency, there is reason to think God did exercise a
degree of choice in making the heavens the way they are. A God who
exercises choice is much closer to the God of Scripture. Although
Galileo changed all of this, and paved the way for a vastly different
view of astronomy, the answer to one set of questions raises a whole
different set. In short, the heavenly motion still poses ultimate
questions about God, existence, and the origin of the universe. |
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