OBJECTOR: Well, the Pope finally apologized—sort of—for the Church’s condemnation of Galileo. Why did the Catholic Church condemn Galileo in the first place? Isn’t this just another instance of the Church’s opposition to science and reason?
CATHOLIC: You have raised two major questions here. One is the historical question about what happened in Galileo’s life. The other is about the Church’s attitude toward reason and science. Before trying to understand Galileo’s situation, it is important to understand that the Catholic Church supports and encourages the use of reason and the pursuit of science.
OBJECTOR: One of my biology professors in college told me that the Catholic Church has always opposed science. A key example is its opposition to evolution. He ought to know. He has a Ph.D. in biology.
CATHOLIC: You’re right—he should know better. Unfortunately, having a doctorate in biology doesn’t make you a good historian. There are many well-educated people who are ignorant of the basic facts.
OBJECTOR: Such as?
CATHOLIC: Such as the Church’s unconditional support for the pursuit of true science. For centuries, Catholic thinkers like Augustine and Thomas Aquinas have argued that our ability to reason and to engage in empirical investigation is a gift from our Creator. Recently, John Paul II issued a long encyclical entitled Fides at Ratio (Faith and Reason) in which he reaffirmed this long tradition. John Paul himself has given many speeches to groups of scientists praising their work as a fulfillment of human good.
OBJECTOR: So if what you’re saying is true, why did the Church condemn Galileo?
CATHOLIC: Many misunderstandings have grown up around Galileo, so it’s hard for some people to distinguish between historical reality and later myth. To understand Galileo’s encounter with the Church, we must distinguish between two separate historical events and work hard at understanding them from the point of view of the participants, not from our current-day perspective.
OBJECTOR: Two events? I thought they just excommunicated him.
CATHOLIC: No, the first event is the condemnation of March 5, 1616, by the Congregation of the Index. Galileo precipitated this condemnation, but none of his works were mentioned in the text itself. The document condemned the belief in the motion of the earth as contrary to good reason and to Scripture. It prohibited Copernicus’s book On the Revolutions of the Celestial Spheres "until corrected" and completely condemned several other books by theologians who advocated that the earth’s motion was not contrary to Holy Scripture. Galileo had written a similar letter in early 1615 arguing that Holy Scripture did not teach anything about the motion of the earth, either positively or negatively.
Robert Cardinal Bellarmine, himself an accomplished Jesuit scientist, informed Galileo on March 6, 1616, of the Congregation’s decision to prohibit the Copernican or heliocentric system. We have no reliable document of this conversation, but it is generally agreed that the Cardinal told Galileo that he could discuss the Copernican system as a scientific hypothesis, offering astronomical and physical arguments for and against it, but that he must not advocate the theory. Any teacher knows this common distinction. You can and must discuss theories that are questionable, but that’s different from advocating a theory. Galileo agreed to follow the Congregation’s injunction. He continued to work on arguments for and against the theory, but he did not advocate it, even though he still believed that it was true and that good arguments would be forthcoming.
OBJECTOR: Are you saying that Galileo willingly obeyed the injunction not to teach the sun-centered theory of the universe, and that he was able to continue his scientific investigations?
CATHOLIC: Yes. But some of these later events led to his second encounter with the Church in the trial of 1633.
OBJECTOR: Yeah, that’s where the Catholic Church showed its true colors as a repressive institution.
CATHOLIC: Before we make a negative judgment, we should at least understand what led to this second trial. As Galileo developed arguments for the heliocentric system after the condemnation by the Congregation of the Index in 1616, he was greatly encouraged when an old friend of his was elected to the chair of Peter in 1623. Maffeo Barbarini mounted the papal throne August 6, 1623, as Urban VIII. The new pope invited Galileo to visit him, and the two talked together as they walked in the papal gardens. Reportedly, Urban told Galileo that the 1616 decision was an unfortunate one, but that it could not be revoked—or at least that it was not prudent to do so. Urban encouraged Galileo to write a new book on the heliocentric system, but he warned him to be careful not to advocate the new theory, only to offer arguments for and against it.
For the next seven or eight years Galileo wrote the famous Dialogue on the Two Great World Systems, which was published in 1632. The censor of Florence, where Galileo lived, approved this book, but it was condemned by certain other clerics. This is where historical opinion divides. Some thought that Galileo was not advocating the Copernican theory, while others thought that the book clearly did. In essence, the question at the trial of 1633 was whether Galileo had in fact disobeyed the injunction of 1616. Galileo maintained at his trial that he did not advocate the theory in the Dialogue. The official readers of the book concluded differently.
In the end, Galileo was found guilty for disobeying the earlier order. I personally think his abjuration—on June 22, 1633—was motivated by his belief that he should submit to the judgment of the Church because he consistently said of himself that he was a faithful son of the Church. He was placed under house arrest in his villa in Arcetri, just across the river from Florence, for the remainder of his life as his penance. He died in 1642 at 78 years of age. But he was not hindered in his work, since he published his greatest work of science in 1638, The Discourse on the Two New Sciences.
OBJECTOR: Okay, so Galileo was not forbidden to continue his scientific work. But the fact remains that the Church condemned a proven scientific theory by invoking the Bible.
CATHOLIC: We must remember that no one—not even Galileo, has he acknowledged—had proof for the motion of the earth in 1632. Evidence would come later, but that evidence was not available to the judges in 1633. The first experimental confirmation of stellar parallax, for example, did not come until the nineteenth century with Friedrich Wilhelm Bessel’s observations. So believing that the earth was motionless was not absurd in the seventeenth century.
OBJECTOR: Even if there was not firm proof for the heliocentric system and thus for the motion of the earth, the Church still used the Bible to condemn a strictly scientific theory. That’s bogus.
CATHOLIC: Again, we must work hard at thinking historically. Most people today would not use the Bible in a scientific controversy, but that wasn’t the case in the seventeenth century. Many leading thinkers of that day believed that the Bible taught that the earth cannot move. For example, the great observational astronomer Tycho Brahe, himself a Lutheran, thought this way. He believed that this agreed with the physics of motion as then understood. And remember, there was simply no compelling evidence of the earth’s motion. For people at that time, if physics and the Bible seemed to agree, that constituted strong reasons to reject the motion of the earth.
OBJECTOR: But today the Church does recognize that the decision against Galileo was mistake, doesn’t it? Why did the Church take so long to recognize its mistake?
CATHOLIC: Yes, the Church recognizes that the decision was wrong, but that recognition took place long before John Paul II made the formal apology in 1992. Copernicus’s book and thus the heliocentric system was removed from the Index of Prohibited Books in the eighteenth century. The Church, long before the past two decades, accepted Galileo’s approach to the reconciliation of science and Scripture as well founded. For example, Pope Leo XIII issued an encyclical Providentissimus Deus (November 18, 1893) in which he basically endorsed Galileo’s approach to the reconciliation of apparent conflicts between the Catholic faith and science. I say "apparent conflicts" because neither Galileo nor the official Church ever believed that there could be true conflicts between the Christian faith and science. Leo in the nineteenth century, Galileo and Bellarmine in the seventeenth, all affirmed the ultimate agreement between truths of faith and truths of science.
OBJECTOR: But Catholics say that the Church is infallible, that it cannot err. Yet you yourself have said that the Church recognizes its error. Isn’t the Galileo case a clear contradiction to the principle of the infallibility of the Church?
CATHOLIC: The infallibility of the Church is a big subject, too big for now, but I can say this much. The infallibility of the Church attaches to its officially proclaimed dogmas, such as Christ’s two natures or Mary’s Immaculate Conception. These are matters of the highest authority. The Church cannot be wrong in these matters. But in matters of empirical science or anything that is not what is called de fide, the Church can and has made many reversals. The decisions in the Galileo case were disciplinary or procedural, not doctrinal matters at all, even though some individuals in the Church at the time thought they were. If these had been matters of dogma, the Church could not have reversed itself.
OBJECTOR: So, you as a Catholic, what lessons do you think we can learn from the Galileo trial?
CATHOLIC: That the pursuit of knowledge is always a humbling process. And that is good, because humility is one of the greatest virtues.