In popular imagination, the Galileo affair stands as a striking example of dogmatic tyranny and the suppression of free thought. Galileo worked out empirical and mathematical proofs for Copernicus’s heliocentric theory of the solar system. That theory seemed to contradict not only Scripture but also the reigning scientific theories of the day. Galileo fell under suspicion of heresy and the inquisition forced him to abjure his scientific opinions. The incident has proved to be a major embarrassment for the Church ever since, since Galileo has since been proved correct.
Ironically, the Galileo affair makes me appreciate the Catholic Church’s contribution to science, reason, and free thought. Historically, the Catholic church has done far more to encourage free scientific thought than to suppress it. The conceptual background to Galileo’s work was largely Catholic and Catholics were among Galileo’s most ardent supporters and patrons. The controversy itself was more nuanced than many people know. In some respects, Galileo comes off as the narrow-minded party. Galileo’s condemnation was certainly unfortunate, but it is also conspicuous as one of the few such interventions in Church history.
Ancient and medieval Catholic theology encouraged thinkers to hold theories loosely and to subject them to critical scrutiny, especially on matters of physical science. St. Augustine (354-430) warned Catholics against spouting scientific nonsense about the book of Genesis, and proposed creative explanations of the biblical text. St. Thomas Aquinas (1225-1274) also taught that Catholics should be ready to abandon biblical theories if they conflict with science. He stated the principle simply: “One should adhere to a particular explanation, only in such measure as to be ready to abandon it, if it be proved with certainty to be false.” (S.T. 1.68.1) To illustrate, St. Thomas elaborated physical theories by Empedocles, Plato, and Aristotle and speculated on how each might be compatible with Christian faith.
During the Galileo affair, the Church urged Galileo to adopt that same open-minded stance toward scientific explanation. Pope Urban VIII, who was a friend of Galileo, asked him, “Isn’t it possible that your mathematical models are correct, but your physical theory is wrong? Isn’t it possible that other physical theories could also explain the data?” The Pope took what is called an instrumentalist view of scientific explanation. Elaborate your theories, but keep an open mind about physical explanation.
Ironically, instrumentalism is now de rigueur among professional scientists. The implications of quantum physics are so puzzling that there are many different physical theories to explain them. The Copenhagen Interpretation, associated with Nobel Prize winner Niels Bohr (1885-1962), despairs of ever getting to “things in themselves.” Bohr said, “It’s wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature.” David Mermin summarizes Bohr’s position as “Shut up and calculate.” Seen in this light, Pope Urban could almost be considered forward thinking!
During the Galileo affair, Cardinal Bellarmine (1542-1621) was the chief theologian. He went farther than Pope Urban and expressed a willingness to accept the Copernican system if only there were sufficient proof. He wrote:
I say that if a real proof be found that the sun is fixed and does not revolve round the earth, but the earth round the sun, then it will be necessary, very carefully, to proceed to the explanation of the passages of Scripture which appear to be contrary, and we should rather say that we have misunderstood these than pronounce that to be false which is demonstrated.
Far from being obscurantist, scientists at the time did not find Galileo’s arguments to be compelling. In fact, some of his arguments now seem absurd. Galileo wrongly believed that only mechanical action could explain motion. Others had proposed that the moon might have something to do with the tides. Galileo rejected that and argued instead that the earth’s physical motion caused tides by slinging the water around the earth. It was Newton who showed physical influence at a distance, and proved Galileo’s mechanical philosophy to be wrong.
The scientific revolution might never have happened without the Catholic Church. The Church taught the unity of scientific explanation, the contingency and intelligibility of the world, and the dignity of human reason. Optics, astronomy, and mathematics made significant progress in medieval Catholic universities. Theologians like Nicolas Oresme (1320-1382) and Jean Buridan (1295-1363) anticipated many of the important theories in the new physics, such as inertia and the motion of the earth. Copernicus and Galileo were both Catholics, educated in Catholic institutions, and patronized by Catholic authorities. They knew the works of Oresme and Buridan and borrowed from them. Their discoveries were logically continuous with scientific and theological developments in the late middle ages. Once the empirical proof became evident, Catholics enthusiastically embraced the Copernican system.