The Galileo Controversy
The Galileo controversy is often used to demonstrate that the Catholic Church and Christianity are anti-science. The claim is that the Catholic Church persecuted and severely punished Galileo for his scientific beliefs, condemning his scientific beliefs as heretical. However, the historical context of this incident tells a more complicated story characterized by individual personalities and political dynamics rather than a simple clash between religion and science.
Galileo Galilei (1564-1642), a brilliant mathematician, astronomer, and physicist, held the chair of mathematics at the University of Pisa. Galileo made significant discoveries in pure and applied science, did ground breaking work in the mechanics of falling bodies (contrary to popular belief, he did not conduct experiments dropping cannon balls or any other object off the Tower of Pisa). Additionally, Galileo made significant improvements to the design of telescopes.
In 1610, Galileo published his observations of Jupiter’s four moons, and later, the phases of Venus. These findings challenged the prevailing belief that all celestial bodies orbited the earth. In 1611, Galileo travelled to Rome to present his findings. He received a warm reception, particularly from Christopher Clavius, a Jesuit at the Collegio Romano. Clavius, a respected astronomer in Europe at the time, confirmed Galileo's observations and supported aspects of his theses on planetary motion.
In the era of Galileo, three mathematical models were proposed to explain celestial movements:
(1) The Geocentric (Aristotelian or Ptolemaic) system, asserted that the Sun and all planets orbited around a stationary Earth. This perspective was widely embraced by most university scholars as the best explanation of the data they observed.
(2) The Tychonic system, developed by Tycho Brahe, one of the leading scientists of the day, suggested the Earth was stationary, with the Sun orbiting the Earth while the other planets orbited the Sun. After Galileo’s presentations in 1611, this model gained favour with the Pope and the Roman Catholic Church including the future Pope Urban VIII. Although many within the Church still favoured the geocentric model, many Jesuit astronomers had adopted the Tychonic system by 1620. Tycho Brahe’s rejection of the heliocentric theory is very important, because it showed that some of the best minds of the day did not accept the heliocentric view as a correct interpretation of the known scientific data of planetary movements.
(3) The Copernican or Heliocentric system, developed by Nicolaus Copernicus, a Catholic priest, published his findings in his book, “Revolutions of the Celestial Orbs” in 1543. The book was dedicated to Pope Paul III and received a respectful hearing at the Vatican. According to this model, the Sun was center of the solar system, with all planets, including the earth, orbiting around the Sun.
Galileo endorsed the heliocentric system of Copernicus. Initially, he received solid support from the Jesuits, a priestly order known for their pursuit of science and philosophy. However, Galileo faced opposition from secular university professors opposing his advocacy of the heliocentric model. In a 1615 letter to the Grand Duchess Christina, Galileo stated that his theories had “stirred up against me no small number of professors, and that these academics had agitated strongly for ecclesiastical support in their cause.” Contrary to popular belief, Galileo asserted that his main opposition came from secular academics, not the Church, as the secular professors later sought out the Church to support their position.
Galileo’s letter to the Grand Duchess also showcased his sarcastic and abrasive personality. By all accounts, Galileo was monumentally arrogant and belligerent towards any who opposed him. Known as the “Wrangler” due to his argumentative and opinionated nature, Galileo dismissed the professors, stating, “I should pay no more attention to them than to those who previously contradicted me – at whom I always laugh, being assured of the eventual outcome.” Much like Mozart, Galileo was brilliant but often insufferable, leading to the creation of many enemies, even turning his previous friends, the Jesuits, against him.
For example, Galileo published Il Saggiatore ('The Assayer'), where he launched a scathing attack on Orazio Grassi, a highly regarded Jesuit mathematician at the Collegio Romano, for his treatise on comets. Grassi used observations of parallax to argue that comets are further away than the moon. Galileo ridiculed this idea and claimed instead that comets are an optical illusion. His factual error notwithstanding, the harshness of Galileo’s mocking tone and his public humiliation of this Jesuit scientist, permanently soured Galileo’s relations with the Jesuit order and they looked for an opportunity to get revenge against him.
Church officials were willing to have heliocentrism taught as a hypothesis, but not as a fact, given there was no proof for it. In April 1615, Cardinal Bellarmino wrote to Galileo stating that the Copernican/Heliocentric theory was acceptable as a working hypothesis. If there were proof that the earth circles around the sun, “then one would have to proceed with great care in explaining the Scriptures that appear contrary; and say rather that we do not understand them, than that what is demonstrated is false." In effect, Cardinal Bellarmino was asking Galileo to offer some proof for his theory, and if such proof was forthcoming, the Church would be open to (cautiously) considering it.
The Church asked Galileo to substantiate his claims, but he was unable to provide any proofs that stood up to analysis (he was right but could not show he was right). While Galileo had observational evidence, such as the phases of Venus and the moons orbiting Jupiter, it was not “proof” that the earth rotated or that it revolved around the Sun.
The official church position was to adhere to the geocentric/tychonic view unless compelling evidence emerged. Galileo’s sole argument, centred around the tides as evidence of the Earth’s rotation, but this was debunked by Tyco Brahe and other scientists. Without the tidal arguments, Galileo’s model was not considered as more observationally superior hypothesis to the Tychonic model, which was more favoured by the Church.
Although today we understand that the heliocentric theory promoted by Galileo was correct, it is important to reiterate that Galileo’s own evidence didn’t conclusively prove it. His observations of Jupiter’s moons, lunar craters, and the phases of Venus, suggested problems with the geocentric model, but fell short of offering “proof” that the earth rotated or that it revolved around the Sun. From a purely scientific perspective, one could argue that the heliocentric model offered insufficient improvement in explanatory power to warrant replacing the prevailing geocentric paradigm or to reject the Tychonian model, as it was just as observationally valid as the heliocentric hypothesis at the time.
The Copernican/Heliocentric model faced no significant challenges from the Church for 70 years, primarily because it was presented as a hypothesis, rather than as established fact. The turning point came when Galileo asserted the Copernican/Heliocentric model as fact. That is what led to the controversy. In 1616, the Church directed Galileo to cease promoting the unproven theory publicly. Galileo complied for the next seven years, but when his good friend and scientific admirer, Cardinal Maffeo Barberini, was elected as Pope Urban VIII, Galileo resumed publicly teaching the heliocentric hypothesis as fact. The newly elected Pope was a friend of Galileo and a very learned man in the sciences who admired Galileo’s scientific brilliance. Galileo assumed his close relationship with the newly elected Pope would guarantee support. Galileo sought his permission and blessing to write a book about the motions of the solar system. Pope Urban VIII readily agreed to Galileo's request, on the condition that the book “represent all sides of the argument” and present a balanced view of both heliocentrism and geocentrism. The Pope also requested Galileo to mention the Pope's personal view of the matter, which included two ideas. First, the Pope thought the Tychonian view had real merit, and secondly, the Pope suggested that bodies in the heavens perhaps move in ways that are not fully understood – a reasonable notion for the time. Galileo agreed, and in 1632 published his book, “Dialogue Concerning the Two Chief World Systems.”
Had Galileo written his book as promised, there would have been no issue. However, as he had done many times before, Galileo was bent not only on presenting his case, but on humiliating those who disagreed with him. Consequently, Galileo wrote a book far different from what he had promised. The book took the form of a discussion among three men: Salviati, a proponent of heliocentrism, another character supporting geocentrism, and an interested bystander. Unfortunately, the "dialogue" was one-sided. Galileo portrayed the proponent of heliocentrism as witty, intelligent, and persuasive, swaying the bystander to his position. In contrast, the proponent of geocentrism, whom Galileo named "Simplicio" (meaning Fool or Idiot) was depicted as slow-witted, often caught in his own errors, and something of a dolt. This was hardly a balanced presentation of views.
Galileo's greatest mistake was his final twisting of the knife. He fulfilled his promise to mention the Pope's view of the matter, but he did so by putting the Pope's words in the mouth of the dim-witted Simplicio. The Pope's views were well known and everyone immediately realized that it was a very pointed insult. The Pope was a vain man who could not stand for such public ridicule. He was furious and sought revenge, summoning Galileo to Rome to explain himself before the Inquisition.
Things did not go well for Galileo. He was condemned by the Catholic Church as “suspected of heresy”, but was not imprisoned or tortured, though he was shown some implements of torture. Galileo was terrified and agreed to something of a plea bargain. In return for publicly recanting his heliocentric view, Galileo was allowed to return home with a sentence of permanent house arrest. He lived out his remaining years in his home. Curiously, it was during his years of house arrest that he wrote his finest work, “Discourses and Mathematical Demonstrations Relating to Two New Sciences”, a book dealing with motion and inertia that is a cornerstone of modern physics. It is worth noting, that the oft-quoted phrase attributed to Galileo, “And yet it moves,” is a romantic fabrication, which never happened. As is the claim that two priests refused to look through Galileo’s telescope because they thought it was bewitched. Actually the two men were Galileo’s rivals and not priests at all. Ironically, two priests who did look through the telescope were converted to the Copernican position, but this is rarely if ever mentioned.
It is interesting to note that during Galileo's conflicts with the Church, other Catholic astronomers, including the equally famous Johannes Kepler, were openly writing and teaching heliocentrism without Church censure. Kepler even formulated and published the equations describing the orbits of the planets about the sun. Yet he never faced any reproach from the Church.
Almost never mentioned in historical narratives is that Copernicus' work, “Revolutions of the Celestial Orbs”, had been in print for nearly seventy years (published in 1543) before the Church placed any restrictions on its teachings. The Church's first formal response to the Copernican hypothesis was triggered by Galileo's Letter to Castelli, an apology for Copernicanism, which advocated a figurative reading of Scripture in order to resolve the theory's apparent conflicts with the Bible. Although Galileo's approach to biblical interpretation was completely in keeping with the Catholic tradition, it had another more troubling implication. Galileo was asserting, in effect, that where scientific findings conflicted with the literal sense of the Scriptures, scientists should have the right to independently determine what the Bible means. This assertion was tantamount to sanctioning the private interpretation of the Bible, a more “Protestant” view expressly forbidden by the Council of Trent. Unwittingly, Galileo had embroiled the Copernican question in a much larger and more complex controversy over who has the authority to interpret scripture.
Although our 21st century perspective makes us indignant that the 'truth' was being muzzled and declared heretical, it is crucial to address certain misconceptions:
Despite the fact that prominent atheists love to invoke Galileo as an example of the supposed conflict between science and religion, Galileo remained a devoted Catholic right to his death (e.g. he took communion every day). It wasn’t about science versus religion as the atheists of today try to argue. Rather, Galileo’s original conflict arose with secular professors at the universities, not the church. He never renounced his religion and remained a devoted Catholic, even seeing his two daughters become nuns.
Galileo was highly honoured throughout most of his life, particularly within church circles. The Church valued the presence of such a bright scientist among them. The Pope dedicated a special day of honour (a rare privilege) to Galileo to celebrate his scientific accomplishments. Furthermore, the Pope had various conversations with Galileo about his scientific ideas. Galileo was also appointed the first President of the Academy of the Lynxes, founded by the Vatican in 1603 as the first exclusively scientific academy in the world. The Academy changed names over the centuries and today is known as the Pontifical Academy of the Sciences. The Academy is an independent body within the Holy See and enjoys freedom of research. It is non-sectarian in its choice of members and a good number of Nobel Prize winners have comprised its members (e.g. Max Planck, Niels Bohr, Werner Heisenberg, Paul Dirac, Erwin Schrödinger; also included Stephen Hawking an atheist physicist).
Galileo was given the opportunity to produce a book that would give fair representation to all three theories, but he violated the trust the Pope placed in him.
Copernicus and the Jesuits avoided trouble because they refrained from teaching the heliocentric theory as fact and they did not challenge the authority of the church to interpret scripture (Galileo did both). Furthermore, Galileo broke his agreement with the Church by teaching the heliocentric hypothesis as fact.
So why did Galileo face the Inquisition? His arrogance alienated the support of the Jesuits. He presented his ideas as facts without sufficient proof, insisted on the right to re-interpret scripture, and finally, he publically embarrassed the Pope, his closest ally.
The Church was sensitive to the criticisms of the Protestants regarding the interpretation of scripture, compelling them to take a strong stand to defend the Church’s authority to interpret the scriptures. This defense was necessary to counter the notion that any individual could independently interpret scriptures, which seemed too “Protestant” an approach especially coming from one of their own (Galileo being Catholic). Furthermore, these events unfolded within the broader context of the 30 Years War between Protestants and Catholics.
The transcript of the trial revealed there was no grand debate of religion versus science. Rather, the verdict was pre-determined. It declared Galileo guilty of suspicion of heresy. This was simply payback from the Jesuits and the Pope who had been humiliated by Galileo.
While there is no justification for the Pope’s abuse of his position to silence a critic, or the Jesuits seeking revenge, the church’s treatment of Galileo was remarkably restrained by the standards of 17th century Europe. Giorgio de Santillana, Professor of Humanities at MIT, wrote that “We must, if anything, admire the cautiousness and legal scruples of the Roman authorities.” The philosopher Alfred North Whitehead wrote: “In a generation which saw the Thirty Years’ War and remembered Alva in the Netherlands, the worst that happened to men of science was that Galileo suffered an honourable detention and a mild reproof, before dying peacefully in his bed.”
Let’s put what Galileo did in a modern context. John is a brilliant employee in a major corporation, in charge of producing the company newsletter. The CEO of the company holds a view that John disagrees with. John publishes an article featuring a caricature of the CEO entitled, “You Idiot, You Simpleton, You Fool”. John is terminated and blacklisted. In a parallel sense, Galileo “is terminated and blacklisted”, which in Galileo’s day meant public humiliation and house arrest. Galileo faced no torture, no dungeon and was allowed to stay, initially, in the villa of the Cardinal of Sienna for his house arrest, and later in his own home.
I am aware of only one scientist who was sentenced to death by public authorities prior to the 20th century. It was the great chemist Antoine Lavoisier who was guillotined during the French Revolution (Robespierre and the Committee of 12 were atheistic) + this regime was anti-intellectual and anti-scientific. Science texts will freely speak of the Catholic Church and its treatment of Galileo, but almost never find any mention of the French Revolutionary government closing the Academy of Science or its death sentence of France’s greatest scientist.
This was also an exceptional case. The scarcity of comparable instances demonstrates that this was an anomaly not normal practice.
The idea of a schism between the Church and science did not originate in Galileo’s era, but gained prominence in the 1800’s. John William Draper and Andrew Dickson White “invented” the “conflict thesis” which claimed that Christianity and science were at odds over the centuries. This “conflict thesis” was rejected by scholars. However, it caught the attention of the public and became part of popular folklore. To say it began in Galileo’s day is poor history and urban myth, as is the suggestion that the 17th century Catholic Church opposed science solely on the basis of its opposition to one book written by one scientist, about one hypothesis. That is an unreasonable claim.
