Science and Religion Friday: The Galileo Affair, Part 1

As I mentioned last week, I’m first going to examine the understanding of the conflict thesis between science and religion and demonstrate why that particular recollection of history is a bit hazy. Nowhere is this more clearly seen than in the Galileo Affair.

According to advocates of the conflict model, the official Church (here being the Roman Catholic Church) placed Galileo under house arrest (in some versions he was officially condemned a heretic) because his acceptance of a Copernican model of the universe (that was heliocentric or centered around the sun, rather than geocentric, or centered around the earth) was at odds with the Church’s theology and he needed to be stopped. The church only relented, well after Galileo’s death, because of public outcry against this. The Church has been at odds with science (and an obstacle to it) ever since. It is primarily an ideological battle and therefore those who are the slightest bit religious are incapable of seeing past it. That’s the story according to advocates of the conflict model, at least.

This is not nearly the truth of what happened. While it is true that Galileo eventually was placed under house arrest (and that there was resistance to heliocentrism), it is more likely the result of political factors and commitment to Aristotelian philosophy than as a result of any genuine theological argument.

The Setting

Before going any further, I should note that this was almost an entirely localized problem. Although Copernicus’ book had been placed on the banned list of books, this applied only to Roman Catholic countries, the Protestant Reformation movement, which had begun roughly a century earlier, allowed for a greater amount of scientific and intellectual freedom and, it appears, Copernicus’ book was widely available. Galileo read it and thought that Copernicus’s ideas were correct. His observations with the telescope, it seemed, made more sense in a Copernican system than in the Aristotelian or the Ptolemaic system. In particular, there was the problem of the “retrograde motion” of the planets. This is the fact that, certain planets, in particular Venus, seemed to be moving one direction, but would periodically reverse their direction before changing direction again and continue moving the direction they had previously been going.

There were modified versions of the Ptolemaic model, however, that sought to make sense of retrograde motion. Keep in mind that Newton had yet to develop his mathematical system that included his calculation of gravitational force, which as a constant force would prevent some of the more exotic Ptolemaic models impossible. Also, it needs to be noted that the Copernican model could not entirely account for the motion of the planets that had been observed in a telescope, certainly not resolving all the problems of the Ptolemaic models. That problem would not be solved until Galileo’s younger friend, Johan Kepler, proposed his model which included eliptical orbits, thus matching his model more closely with telescope observations. This brings me to my first major point.

The primary debate around which the Galileo affair centered was not between an outdated religious world view that could account for none of the data and one that accurately fit the data but was more modern. Instead it was between two competing physical systems, both of which could account for the data observed, but in different ways (and not enough investigation into gravity had been done to rule out Ptolemy’s system). Neither system resembled our solar system as it is understood today. While the Copernican system may seem closer to what we now know, prior to Newton and Kepler, there was no way to know this would be the case, especially at the time of the Galileo affair.

I should also note, as it will become important later, that Ptolemy’s system was, as you may have gathered from above, an attempt to reconcile Aristotelian physics with the observed motion of the planets. The picture given above is just one such conceptualization. There were others, including some where Venus revolved around the sun, with the sun revolving around the earth. In all of these, including the Copernican conception, the overarching factor that seemed to limit them was from a concern with beauty. In order for the model to be correct, it needed to be both uniform and, above all else, beautiful. This problem held back both the Ptolemaic and the Copernican system. While Kepler’s model (of eliptical orbits) would eventually prove more accurate, it was not uniform and thus not beautiful or simple (a secondary criteria). At its root, this is what the genuine issue was.

Still, while these may have been idealogical issues that have little to nothing to do with Christianity, next week we will examine the deeper personality issues that may have in fact played an even more prominent role in the eventual censure of Galileo’s teaching. And the trouble really began, as we will see, with Galileo’s criticism of Aristotle in non-astronomy related physics.

  7 comments for “Science and Religion Friday: The Galileo Affair, Part 1

  1. September 7, 2012 at 11:21 am

    Thank you so much for clearing up a lot of the myths that everyone seems to take for fact. It always makes me angry when people act as if the church has been and always will be anti-science when it is really not.

  2. September 13, 2012 at 11:21 am

    With some other minor developments that are beyond the scope of this essay, this was how matters remained until the publication, on his deathbed (literally) of Nicholas Copernicus’ (1473-1543) De revolutionibus orbium celestium. In that work he gave a mathematical account of a universe centred on the Sun, in which all the planets (and the Sun itself) rotated on their axes and around the Sun. Although Copernicus interpreted his model not as an instrument but as a description of reality, a preface was added to his work by Andreas Osiander which asserted to the contrary in order to avoid the censure of the Church. The reception given to Copernicanism varied between countries and over time, but one of the most important responses was given by the Danish astronomer Tycho Brahé who developed an alternative system, according to which the planets orbited the Sun and the Sun, in turn, orbited the Earth. This retained geocentrism and geostaticism, winning the support of astronomers in the instrumental tradition. Others, however, complained that it was merely a mathematical concession that did not address the physical difficulties with the Ptolemaic system that were brought up by the appearance of many comets between 1577 and 1596. Aware of these issues, Brahé could not bring himself to accept Copernicanism. A more detailed account of the background may be found in a study of the history of astronomy (cf. Kuhn, 1971 and Fantoli, 1996 for recent examples), but this was the situation when Galileo arrived on the scene.

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