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January 27, 2012

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Again, another fascinating and very complicated topic. Here are some thoughts on the matter.

Galileo shared Kepler's conviction that God created the world with a mathematical structure. But not everyone did.

And she goes on to say,

Galileo attracted controversy because he insisted that the Copernican system was not just a useful calculating tool but physically true. The central question at stake was thus the status of mathematical truth: Does mathematics tell us what is true in the physical world? This was a philosophical question, not a theological one. And Galileo's main opponents were not churchmen but the Aristotelian philosophers in the universities. For them, mathematics was not high on the list of what makes the world what it is.

Yes, it is true that Galileo and Kepler interpreted nature mathematically in a new and fruitful way. It is also true that this approach was not generally championed by Aristotelians of the day. Nancy is right that the Aristotelian approach was largely qualitative and less quantitative. Bodies were regarded as hylomorphic compounds of matter (a passive principle) and form (an active principle); bodies were thought to be composed of various combinations of the four elements (viz. earth, air, water, and fire). A fifth element, ether, was posited to explain the motion of superlunary bodies. The elements were considered as derivative from a combination of prime matter and the four primary qualities of wet, hot, dry, and cold. Each element was thought to strive toward a certain place. Earth and water strove toward the center of the universe (which was thought to coincide with the Earth’s center) and fire and air strove upward. Bodies were regarded as having natural places toward which they strove. Their striving, moreover, is determined by the dominant element. Motion in accordance with this striving was regarded as “natural,” and motion against this striving was regarded as “violent.”

That is a bit of the Aristotelian physics that was standard, and it did not elevate mathematics the way Kepler and Galileo did. But again, it is good to keep in mind that many of those that approached nature mathematically were actually inspired by Plato’s Timaeus, not discouraged by it. We have already seen Plato’s influence on Kepler’s mathematical approach to nature. Copernicus, in his 1543 De Revolutionibus, quoted on the cover of the book “Let no one ignorant of geometry enter,” which according to tradition was inscribed over the entrance of Plato’s academy. The revival of interest in Plato was actually a contributing factor to calling the authority of Aristotle into question. Here again, therefore, it must be admitted that the new mathematical approach to nature was derived not from the Bible or from the dominant Christian tradition of the time but at least partly from a revival of the Platonist idea that God wrote nature in the language of mathematics. It is true that Plato taught that matter is inherently inexact, which explains the discrepancy between mathematical models and empirical data. But during the time of Galileo and Kepler the mathematization of nature was, all things considered, a far greater step toward Plato than away from him. I wish this aspect of history was emphasized more in these posts.

What about the claim that Galileo’s opponents were not mainly clergymen, but Aristotelian philosophers at the universities? What is important to remember here is that the Christian tradition of Galileo’s day was in many respects thoroughly Aristotelian. Despite the fact that Aristotelian science dominated the scholastic tradition, his works in natural philosophy were not always enthusiastically welcomed. His works in natural philosophy were banned in Paris in 1210 because of religious anxieties. In 1277 219 propositions connected in some way with Aristotle were condemned by a document drafted by a bishop. Even the natural philosophy that dominated scholasticism, therefore, had to survive religious prejudices before it would earn its place amidst the new prejudices at which Galileo would fall victim. By the middle of the thirteenth century, however, Aristotle’s natural philosophy began to dominate. This is one of the reasons that we cannot artificially bifurcate the Aristotelian natural philosophy from the Christian tradition in which folks like Galileo and Descartes live. That tradition, like contemporary Catholicism in many respects, was at once both Christian and Aristotelian, and no neat way of separating them exists.

And of course, Galileo’s main opponents were clergymen! Conservative religious anxieties are known to have contributed to the prejudice against Galileo’s works. Because of a letter Galileo wrote to Benedetto Castelli, the Inquisition took an interest in Galileo. In 1616, a committee associated with the Church found Copernicanism false and heretical. The Inquisition, however, issued no official condemnation. Galileo was warned by Cardinal Bellarmine to not defend or teach Copernicanism, and Galileo promised to comply. In March of the same year, the Congregation of the Index issued a decree declaring that geokineticism was false and contrary to Scripture. Circulation of Copernicus’ De Revolutionibus was halted.

When Galileo’s Dialogue on the Two Chief World Systems, Ptolemaic and Copernican was published in 1632, it seemed to the religious authorities that Galileo was defending exactly what he promised not to. The Church’s religious and authoritarian sensibilities were offended, and in the summer of 1632, sales of the book were prohibited and the Inquisition summoned the 68 year old Galileo to Rome for interrogation. Despite the fact that Galileo was ill and the plague was a very real danger, Galileo was forced to go to Rome on threat of being coercively brought there in chains. Galileo was interrogated under threat of torture and in 1633 he was found guilty of “vehement suspicion of heresy” and sentenced to house arrest for the rest of his life. Copernicanism was declared false and contrary to Scripture, though the declaration did not have the authority to render such a senseless verdict an article of faith for devout Catholics.

If that doesn’t suffice for qualifying as a main opponent, then I don’t know what would. It is true that Galileo did not have decisive proof that the Earth moved. The argument for geokineticism for which he was most proud was an argument based on the motion of the tides, and it is now known to be flawed. Furthermore, to explain the lack of observable stellar parallax (pointed out by Aristotle), Galileo had to posit that the stars were further away than anyone had imagined. We now know he was right about that, but some at the time felt that this hypothesis was merely an ad hoc hypothesis unsubstantiated by independent evidence and designed merely to save his theory. Furthermore, the Tychonic hypothesis, which according to Thomas Kuhn is mathematically equivalent to Copernicanism, was a geostatic theory that was still a viable option in Galileo’s day. The Tychonic hypothesis was considered a compromise, since with Aristotle and the traditional reading of Scripture it was geostatic, while with Copernicus it departed in desirable ways from the Ptolemaic system. These features of the Tychonic system obstructed any immediate inference from Ptolemaic astronomy is false to Geokinetic theory is true.

Nevertheless, it would be historically naive in the extreme to think that the Church’s opposition to geokineticism was explained wholly by a shrewd consideration of the empirical data. It was not.

In summary, while it is true that the new approach to nature emphasized mathematics more than the scholastic approach, it is also true that in many respects this new approach represented a step toward the Greeks, or at least toward Plato. The Christian tradition of the day had been so dominated by Aristotelian philosophy that was can only speak of a Christian Aristotelianism that held progress back. Those who sought to overthrow the authority of Aristotle found it useful to appeal not necessarily to the Bible, which was often appealed to by the geostatic traditionalists, but rather to Plato’s Timaeus, where we are told that God created the world according to the language of mathematics. Nancy writes, “When he declared that the book of nature was written by God in the language of mathematics, those were fighting words,” I wish should would have also told her readers that those were Plato’s words and known to be his words by folks like Kepler and Copernicus. This aspect of Plato’s thought proved far more influential for the scientific revolutionaries than his ideas about the inexact nature of matter, but Nancy Pearcey is largely silent about that. Finally, although Aristotelianism opposed Galileo’s outlook, it is also true that the conservative Christian thinkers of the day opposed it, partly because of their tutelage under Aristotle. Another major source of contention was the Bible itself, and because of Galileo’s defense of Copernicus, he fell victim to the conservative religious prejudices of an authoritarian institution paranoid because of the Reformation that anyone would publish private interpretations of Scripture and whose piety could not bear the truth of geokinetic theory.

Oops, I should have written,

Nancy writes, “When he declared that the book of nature was written by God in the language of mathematics, those were fighting words.” I wish she would have also told her readers that those were Plato’s words and known to be his words by folks like Kepler and Copernicus.

This always puts in my mind a solid caution against any who want to baptize a particular scientific theory or dogmatize Biblical interpretations that accommodate those theories.

And Galileo's main opponents were not churchmen but the Aristotelian philosophers in the universities.

Those pesky university professors again.

I suppose it was university professors that hauled Galileo off to 'court' and forbade Galileo to 'hold or teach'.

I suppose it was university professors that held Galileo under house arrest for life.

Darn those university professors!

Darn them!

RonH

Ron,

Which kind of "opponent" do you think she meant?

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