October 29, 2011

Limits to Popular Wisdom: Apropos “Galileo got outvoted for a spell”

Wolf Schäfer


Rick Perry may be “anti-science” (Huntsman), but he got the sound bite of its history right: Galileo was indeed “outvoted” in 1633. The only problem is that Galileo was correct and the inquisitors of Pope Urban VIII were wrong. The earth does move, and now it is warming up. What Governor Perry would like to outvote – human induced climate change – could be true in the end, too.[1]

The Pope’s men did their best to reach a sound verdict about Galileo’s public justification of the earth’s motion and the sun’s stability. Finding heliocentrism “absurd and false,” as well as a “pernicious doctrine,” the Cardinals of the Roman Inquisition forced Galileo to kneel down and “abjure, curse, and detest” the scientific falsehood of the Copernican “opinion.” The incriminated books of Copernicus and Galileo remained banned for about 200 years. Later, in 1992, John Paul II acknowledged the scientific blunder of his predecessor’s tribunal.

Yet declaring a true theory false is a big blunder only in hindsight. Cutting-edge science always hovers in a cloud of uncertainty. Paradigm competitions are rarely resolved at once. From Copernicus’ initial publication in 1543 to Newton’s magisterial synthesis in 1687, the heliocentric theory took 144 years to displace the geocentric world system and become the new paradigm.

In the beginning, opponents of Copernicanism had the upper hand. Everybody could see that the sun was moving and not the earth. Scripture confirmed, “The sun rises and sets and returns to its place.” An arrow, shot straight up, returns to the shooter, and does not fall behind. Sophisticated critics noted that a star’s position observed from the vernal and autumnal vantage points of a moving earth must appear different (stellar parallax), but there was no observable difference until 1838. This problem led Tycho Brahe, the best naked-eye astronomer of the time, to propose a geoheliocentric system in which the moon and the sun orbit the earth and all other planets revolve around the sun.

Galileo’s acclaimed telescopic discoveries – lunar mountains and craters, the moons of Jupiter, and the phases of Venus – contributed supporting evidence to the Copernican system, but also to the Tychonian compromise, which was favored by eminent Jesuit astronomers such as Orazio Grassi and Christoph Scheiner. Yet Galileo never acknowledged the theoretical equivalence of the Tychonian alternative. Blinded by premature confidence and a vainglorious and insulting attitude, Galileo managed to turn the Jesuits, his initial supporters, into enemies.

The recognition that Galileo’s heresy was the right theory became easier over time. Betting on the wrong scientific theory is after all a diminishing risk. But the assumption that up or down votes can divine the truth of scientific theories is a clear and present danger. We must understand that as physicists cannot turn to the electorate to measure the gravitational constant or choose the cause of gravity, the Tea Party movement cannot determine the nature, causes, and consequences of global warming. The wisdom of crowds has limits.



[1] The difference of opinion about climate change between Republican presidential candidates Jon Huntsman and Rick Perry was addressed by John Harris from Politico. Turning to Governor Perry of Texas, HARRIS: “Just recently in New Hampshire, you said that weekly and even daily scientists are coming forward to question the idea that human activity is behind climate change. Which scientists have you found most credible on this subject?” PERRY: “Well, I do agree that there is – the science is – is not settled on this. The idea that we would put Americans’ economy at – at – at jeopardy based on scientific theory that’s not settled yet, to me, is just – is nonsense. I mean, it – I mean – and I tell somebody, I said, just because you have a group of scientists that have stood up and said here is the fact, Galileo got outvoted for a spell.” See “The Republican Debate at the Reagan Library,” The New York Times, 7 September 2011 (transcript).