The Inquisitor's Telescope: The Science in Galileo's Silencing

by Jude Chua Soo Meng

In the epic movie based on the novel The Name of the Rose by Umberto Eco, Brother William of Baskerville, a Franciscan Friar played by Sean Connery, was asked by the abbot of the Benedictine monastery he was visiting to investigate a recent murder that had occurred in the abbey, and about which vital clues were to be found in the library, though it was not accessible to the son of St. Francis. When asked how then he might go about that resolve, the abbot replied that William, who once had been an Inquisitor and was trained in the Aristotelian science, could travel to places without being there in body. He was, of course, referring to the fact that the Franciscan was trained in the philosophic art of deduction, by which he could discover distant facts from present evidence. His two tools were the syllogism, i.e., reason, and sense data, i.e., experience. His science, as the philosopher Aristotle had well defined it, was to trace the causes of effects — effects known by sense, and causes known by reasoning from the effects.

William of Baskerville, to the extent that he was a Franciscan, was most likely a Scotist, and the Dominicans and Jesuits in the days of Galileo Galilei (1564–1642) to whom we shall return to later, were more likely then not Thomists, as am I. Nonetheless insofar as they were schoolmen or scholastics trained in Aristotelian science, they were avowed realists — minimally, they were all committed to making reason and experience cohere, without giving up on either. This tradition, exemplified by the philosopher in his Physics and Metaphysics, charts out a golden middle between two methodological extremes which deny reason or sense. On the one end stands Parmenides who divided reality into being and non-being. Forced by the principle of non-contradiction to deny the possibility of change, insofar as change is excluded when being comes from non-being or vice versa, he considered the experience of mutation and motion an illusion. Heraclitus, on the other hand, preferred sense to reason, and therefore affirmed change at the cost of denying the significance of the principle of contradiction, and hence sacrificed reason for the world of flux. Between them stands Aristotle, who insisted on the validity of both, and divided being into actual and potential being besides non-being or pure privation. Change, which sense evidenced, was a progression from potency to act, rather than from pure privation, and hence he made reason and experience cohere, leaving the principle of non-contradiction intact, and indeed, presupposed it.

It is unfortunate that Aristotelian scholastic science has fallen into disrepute, perhaps because of its futility with regards to analyzing electricity, or making computers, or providing us with modern technological comforts, which futility in question I do admit. Still, such objections to scholastic science are not so much against its validity per se, but rather are objections to fitness for yielding such results as perhaps modern science does when it investigates the same matter. For just as the science of medicine should not be expected to yield the same discoveries when applied to a body as, say, the science of theology, so likewise scholastic science need not be expected to analyze electricity in the same terms as does a modern physicist. And the mark of an educated man, as Aristotle says, is to know the kinds of certainty that each science can yield, and expect accordingly. And just as someone expecting his light bulb to glow will find the scholastic discourse on act and potency most disconcerting, one struggling to explain multiplicity will find the question-begging talk of photons or corpuscles of absolutely no consolation to a confusing charge of monism.

A stronger and more proper objection, which seems to me more widespread and which attacks Aristotelian science as science, is that it is unscientific, in the sense that it disregards evidence for theory. A common and I think ironic misconception is that the historical entry of experimental science during the Renaissance, which laid a distinct premium on the empirical evidence gathered through sense observation, was a radical corrective to the imaginary speculations of the Renaissance Aristotelian schoolmen — speculations which had no regard for the evidence of the senses.

Galileo, who peered through his telescope at the surface of the moon and saw that it was cratered and hence not a perfect sphere as Aristotle thought the heavenly bodies were, is often cited as the paradigm case of the demise of Aristotelian science. He represented the redeeming advent of real science, an experimental science which respected sense evidence and adjusted theory to fit it, rather than the other way around. In this same way, popular history writes, Galileo vindicated the heliocentric astronomical model of Copernicus, who had speculated against Ptolemy that the earth revolved about the sun rather than the other way around.

Yet it is interesting to note that Galileo, whom many think a father of modern science, despite his many other achievements, did not always live up to the effort to adjust speculation to sense experience, if by experience we include observed and recorded data. And this is especially manifest in his battle against the Renaissance schoolmen, the latter of whom against Galileo preferred the geocentric Aristotelian-Ptolemaic model of universe. Even though eventually history vindicated him on getting it right with the earth revolving around the sun, yet in his time, the evidence Galileo had did not at all cohere well with his proposal that the earth revolved around the sun, because for him the earth rotated in a circular orbit. This he insisted on proposing as a theory, rather than merely a hypothesis, as the Jesuit Robert Bellarmine, who investigated his submission, and then Pope Urban VIII, had suggested he do.

It was not until Johannes Kepler (1571–1630) came along with the idea that the orbits were elliptical that the data finally fitted the hypothesis, and therefore vindicated him. But this does not at all reverse that fact that it was the Renaissance Aristotelians — Jesuits and Dominicans included — and his Inquisitors, rather than Galileo, who had lived up to the effort to always adjust theory to experience, precisely because the thesis that the earth revolved about the sun with a circular orbit did not fit with the astronomical data collected by Copernicus and other astronomers, and therefore could not be admitted as a sound theory. Hence the Copernicus-Galileo hypothesis, all things being equal, was as bad a theory as the Ptolemaic-Aristotelian one, since neither cohered well with the data. In fact, although there were too many epicycles in the Aristotelian theory, it still stood a good chance.

In other words, it was ironically the Inquisitors who, having peered through their own Aristotelian telescopes, were more faithful to the basic principles of science as science, insofar as they insisted on attending to the evidence of the astronomical data and refused to admit a theory such as Galileo's which failed to cohere with the facts. In refusing to sanction Galileo's “bad theory,” the schoolmen were the ones who were truly faithful to the realist effort to adjust speculation to fit sense experience — a realism that modern science boasts of and claims as a badge of prestige. They followed the example of Aristotle, for whom, as against Parmenides, the evidence of the senses was not to be disregarded and theory bent in its direction. Hence when they silenced Galileo by merely showing him the instruments of torture, they had science on their side.

Ironically, it is precisely by following the Aristotelian realism of the schoolmen that the Copernican theory can in fact be vindicated, because the data would require that we admit Johannes Kepler's theory of elliptical orbits, to the extent that it fitted the facts. If we had followed Galileo's methodology, which has no concern for the coherence of data and theory, the Copernican theory could not be justly vindicated, and we would instead be writing silly plays to humiliate our objectors just to get our position through, as did Galileo, who in fact wrote a Dialogue Concerning the Two Chief World Systems (1632) in which he portrayed Pope Urban VIII as a fool.