Thoughts on Galileo

[shernren]

I've been doing some reading on Galileo and his affair with the Catholic church. It's becoming clearer to me that literalism indeed had a lot to do with it, but not in the usual way we think of today. An important issue in Galileo's trials was the Tridentine declaration that individual interpretation of the Bible would not be allowed, and that the Catholic church's consensus in the form of the agreement of the Church Fathers on a particular issue was to be the official interpretation.

While this at surface value did not exclude the science of Copernicus and Galileo, it engendered a culture of literalism in the Catholic church, and when Galileo came along he (or more precisely Foscarini, who wrote a letter endorsing Copernicanism with explicit reinterpretations of the Bible) was censured for private reinterpretation of the Bible as well as for heliocentrism itself. Interestingly, of the two trials that Galileo underwent, the second had almost nothing to do with the Scripturality of heliocentrism - it focused on Galileo's character and whether or not he had obeyed the injunction he received at the first trial, which was completely about whether or not heliocentrism was Scriptural.

It's not accurate to paint the Galileo affair as a "church right, science wrong" decision by the Catholic church. The reverberations of the Protestant Reformation and the Catholic counter-Reformation were still being felt through the Tridentine conclusions. Having said that, AiG's take on the matter ( http://www.answersingenesis.org/tj/v14/i1/galileo.asp ) is quite unsatisfactory: it never mentions anything about the Tridentine decisions, or the intense debate about the Scripturality of heliocentrism that led up to Galileo's first trial.

 

[GratiaCorpusChristi]

Galileo was a bit of a jerk....

 

[shernren]

... and my thread title was misleading. As I read on it becomes clear that the action on geocentrism wasn't all about Galileo. It was about the atmosphere of the times and how it affected multiple players on the emerging field of astronomy.

And here again is another example of how AiG can be almost right but still crucially wrong.

Thesis 1. The Copernican system was well regarded by church officials

An open defence of the Copernican system was, in principle, without danger. The Ptolemaic system had been denied by many high officials and Jesuit astronomers even before Galileo was born. As the example of the Imperial Court astronomer, Johannes Kepler (1571–1630),16 proves, many of them followed the Copernican system.

‘The Jesuits themselves were more Copernican than Galileo was; it is now well recognized that the reason why Chinese astronomy advanced more rapidly than European astronomy was simply because Jesuit missionaries communicated to them their Copernican views.’17
‘While Martin Luther called the author of De revolutionibus orbium coelestium [i.e. Nicolaus Copernicus (1473–1543)] a “fool”, which will turn “the whole art of Astronomiae upside down”, the book had not been fought by the Vatican. It was seen as a “mathematical hypothesis”, but had already been used as an aid in astronomical calculations for a long time. Only some time after leading Jesuit scientists like Pater Clavius had agreed to the trustworthiness of Galileo’s observations, did Copernicus and his followers become “suspicious”.’18
​

The book by Copernicus was not placed on the Vatican Index19 until 1616 to 1620 and was readmitted to the public after some minor changes.20 Only Galileo’s Dialogo remained on the Index from 1633 till 1837.21

It becomes prudent to ask why Copernicus' book was placed on the Vatican Index in 1616 in the first place. Two events brought about the banning. The first was a publication in March 1615 by Paolo Antonio Foscarini (with a very long title!) now known as simply his Lettera, which provoked a complex series of attacks and defenses culminating in Cardinal Bellarmine's finisher that anything contained in the Scriptures is a matter of "faith and morals" simply by virtue of being inspired by the Holy Spirit and therefore not amenable to individual interpretation as decreed by the Council of Trent.

The second was a personal attack started by Tommaso Caccini against Galileo and his followers. In the first version of the attack, started about the beginning of 1615, Galileo not only believes in heliocentrism; his disciples (according to Caccini) also believe that God is not a substance but an accident, God is a sensory being, and the miracles attributed to the Saints are not true miracles. Here is a strong personal attack, modulated by the testimonies of Ximenes and Attavanti, making clear reference to Galileo's Letters on Sunspots. This culminated in a judgment began on 19 February 1616 by the Consultors of the Holy Office on the propositions:

1. that the sun is the center of the world, and consequently is immobile of local motion.
2. that the earth is not the center of the world nor is it immobile, but it moves as a whole and also with a diurnal motion.

The first proposition was judged as "formally heretical" and the second as "at least erroneous in faith" (both technical terms used in delivering theological judgments) 4 days later, and on 5 March 1616 Copernicus' De revolutionibus, Foscarini's Lettera, and Zuniga's Commentary on Job were put on the Index for teaching heliocentrism.

Amidst all this how can AiG claim that "an open defense of the Copernican system was without danger"? The only reason why Galileo's books were not directly put on the list as well was because the message would have been clear enough, and reinforced by a personal meeting with Cardinal Bellarmine where he would be forbidden from defending or holding Copernicanism. So clearly, whatever started the trials, it wasn't a personal grudge against Galileo, or his Letters on Sunspots (alluded to in Caccini's accusation) would have went on the Index as well. While the trial in 1633 was based on Galileo's character and his obedience to the decree of 1616, the trial in 1616 wasn't - theoretical considerations (theological ones at that, not scientific ones) were reached about Copernicanism independently of Galileo or any other personalities teaching it, and in the case of Galileo at least, Bellarmine was perfectly willing to defend the man while condemning his teachings.

 

[shernren]

Some creationists may say that it was Aristotle which convinced people to adopt Ptolemaic cosmology, instead of Scripture. That argument doesn't hold up, for there were actually quite a few cosmological theories in competition around the time.

The dominant physical paradigms of the time were that a simple object could only have one motion, and that the heavens were structured and orderly (so that today's notion of a universal vacuum would be quite unacceptable to most of them). Within those paradigms, the cosmologies had to explain, relative to the earth, the motions of:

1. the Sun.
2. the Moon, and its phases, as well as Sun-Moon interactions i.e. eclipses.
3. the planets. They move against the background of the fixed stars and occasionally exhibit retrograde motion i.e. they slow down, reverse their direction of motion for a few days, and then resume their normal direction, doing a loop in the skies.
4. the fixed stars. They aren't actually fixed relative to the earth, but move slightly in the precession of the equinoxes, and do so at non-uniform rates at that.

With these observations at hand, there were a few possible theory choices:

1. Homocentric theory. This is (pre-)Ptolemaic cosmology at its most theoretical. The planets orbit the earth in spheres that were perfectly centered on the earth. Forget about how the moon changes in size or the planets in brightness: Aristotle says the earth must be at the center of the universe and that's that. In practice, you could add on some spheres - usually over fifty - and compound their motions (each sphere only having a single simple motion) to get some sort of workable approximation. It wasn't pretty.

2. Neo-Ptolemaic cosmology. The defenders of Ptolemaic cosmology never kept it ossified - the cosmology was updated as the observations came in, contrary to today's popular impression, even though it got progressively harder. For example, the observation of novae (new stars, now what we know as supernovae) in the sky led Clavius, a leading Jesuit astronomer, to conclude that Aristotle was wrong and that the heavens were corruptible after all. There was internal controversy - e.g. how to deal with the fact that the precession of equinoxes wasn't regular but sometimes faster or slower. The conventional position (Alphonsine trepidations) was that the spheres controlling the fixed stars' motions occasionally shook, but Clavius adopted Copernican ideas that in fact the Earth had some complex motions that caused the fixed stars to "tremble" relative to us - again, hardly unquestioning acceptance of Aristotle.

3. Fluid heavens theory. This was held by some people, notably Cardinal Bellarmine (of the first trial against Galileo), and was distinctly non-Aristotelian. Its argument is captured in the poetic phrase "like birds through the air, or fish in the water": so also the stars and planets all moved under their own power through a fluid heavens, instead of being confined to invisible cosmic spheres. Clavius lambasted this theory for not really being able to predict anything, which makes sense. But what was important for the Cardinal was not that it followed Aristotle (it didn't) - it followed Scripture, or how he read it.

4. Tychonic models. These models also dispensed with the invisible cosmic spheres, but it also took the next step and put all the other planets in orbit around the sun, which then orbited the earth farther away from the moon. This model was popular among the Jesuit astronomical community after Copernican theory was deemed heretical. It wasn't Aristotelian in any way. But at least it kept the earth central and immobile, if nothing else.

5. Copernican heliocentrism. We know who won.

The question that creationists should ask (and be asked) when they look back at this episode is: what is the common denominator among all the non-Copernican beliefs? They weren't all Aristotelian. Even Ptolemaic cosmologists were willing to abandon the idea that the heavens were immutable after they observed novae in the sky and used parallax (or lack of it) to conclude that those novae must be among the fixed stars. And it wasn't all about attached baggage either: the Jesuits had no problem with using the Tychonic models (although that change largely took place after Galileo's condemnation). There is only one common factor that unites the non-Copernican cosmologies:

the centrality and immobility of the Earth, which they read out of the Bible, and which the church thus approved.