A Teachable Moment - Galileo Division.

Subtitle: There really was a dispute by the scientists at the time over the scientific basis of Galileo's heliocentric theory.

Sarah Posner at RD writes:

In last night's debate, Rick Perry, stumbling over his answer denying the science of climate change, opined, "Galileo got outvoted for a spell." Of course Galileo, considered the father of modern science, wasn't "outvoted" by other scientists, he was subjected to an inquisition by the church for being a heretic.

Ironically, although Posner wants to accuse Perry of being stupid, it is Posner who demonstrates that she has uncritically accepted one of the great urban legends of modernity.

The truth was that the Catholic Church handed the issue of Galileo's claim that the Earth revolved around the Sun to the leading scholars of the day, who, like the pro-AGW scientists today, used their position of power and control over the universities to get a little political pay-back from an upstart they didn't much like. The academic politics of the issue can be seen in a letter from Cardinal Bellarmine which advised that "But to want to affirm that the Sun, in very truth, is at the centre of the universe and only rotates on its axis without traveling from east to west, and that the Earth is situated in the third sphere and revolves very swiftly around the Sun, is a very dangerous attitude and one calculated not only to arouse all Scholastic philosophers and theologians but also to injure our hold faith by contradicting the Scriptures…."

In respsonse to a recent shot by James Fallows at Perry's claim that the acceptance of heliocentrism was retarded by the jealousies of contemporary scientists, Pajama Media recounts:

Fallows further mocks Perry by comparing him to a person who says, “Hey, I’ll mention Galileo! Unfortunately in mentioning him, I’ll show that I don’t know the first thing about that case….” But although Fallows may think that he’s the one who really knows the first thing about Galileo, he may not know the second and the third thing — including what the Church’s main beef with Galileo was, and the position of Galileo’s scientific contemporaries on the subject of heliocentrism. The latter is especially important to Perry’s analogy, since he was talking about disagreements among scientists, both in Galileo’s time and now.

The Church had initially become upset with Galileo for two main reasons, neither of them the conventional “church vs. science” objection of legend. His first offense was committing theological overreach in their eyes when he stated that heliocentrism did not contradict the Bible because scripture should not be interpreted literally. The second was a kind of scientific hubris: Galileo’s assertion that heliocentrism had been proven (incontrovertibly, as it were) rather than being a tentative working theory. In addition, many of Galileo’s fellow scientists, although split on the matter, were more against Galileo than with him, just as Rick Perry said. The reason for their skepticism was not theology, it was that Galileo’s model was inconsistent with the best empirical observations of the time — although of course, in retrospect, his theory turned out to be correct.

The most important problem with Galileo’s heliocentric theory, and one that was widely recognized by his scientific contemporaries, was the lack of “observable parallax shifts in the stars’ positions as the earth moved in its orbit around the sun.” It was only much later that instruments were designed that were sensitive enough to detect the shifts. Therefore, Galileo lacked scientific evidence to prove his theory, and many leading astronomers of the day rejected it. The renowned Tycho Brahe was one of them; he had his own competing theory, which was a Geo-Heliocentric hybrid in which the sun revolved around the earth but the other planets revolved around the sun, a system that conformed better than Galileo’s with the lack of observed stellar parallax and which remained in scientific favor for a long time.

I have written that Galileo’s theory turned out to be correct, but that is actually an over-simplication. Galileo was indeed correct in stating that the planets revolve around the sun. But he also believed that the sun is the fixed and unmoving center of the universe, which we now know to be incorrect.

This error does not contradict the fact that Galileo was a scientific giant. But the story is a reminder that even the brilliant make mistakes, and that science does not advance by simple progression from ignorance to perfect knowledge, nor is it proven by consensus. It moves in fits and starts, sometimes with small wavering steps and meanderings, sometimes with great leaps. Sometimes it lingers for a while in blind alleyways. But it is always incomplete, and must continually be tested and questioned.