Galileo Galilei was an Italian physicist, astronomer, mathematician and philosopher who was born on February 15, 1564, in Pisa and died at the age of 77 while living in exile in the small village of Arcetri, near Florence. This year he has been honored worldwide for his important contributions to astronomy.
Galileo and the Inquisition — A Historical Perspective
The formal name for the organizations that developed in the Middle Ages to combat heresy within the Catholic Church is Inquisition.
It appears as a strategy to deal with oppositions between power and truth, power and freedom of thought, or religious belief and scientific fact, but in reality, it is as old as human history.
Therefore, whether forbidden or openly practiced, inquisition – religious or political – is relevant today.
During Galileo’s lifetime, there were two possibilities.
On the one hand, the Catholic Church, the hegemonic force of the time with total sociocultural control and on the other hand, the Roman Jesuit college, created in 1551 by St. Ignatius of Loyola, was the ultimate expression of truth.
Catholicism was the dominant ideology of the time and was supported by religious convictions and concepts that had been handed down from Aristotle and Ptolemy.
The other scenario was represented by a group of individuals who attempted to understand natural events and provide a logical justification of the cosmos.
This group included Galileo, who acquired knowledge from Copernicus, Tycho Brahe and Giordano Bruno and discussed their theories with Kepler. Galileo questioned nature with experiments and nature revealed its secrets to him, as scientists have done since adopting his legacy.
What exactly was Galileo’s “sin”?
But why was it targeted by the authorities? Galileo used experiments to disprove Aristotle’s claim that heavier objects fall faster than lighter ones. He was able to show that all bodies fall at the same speed in a vacuum. The idea of gravity was unknown at that time.
He was forced to leave Pisa, where he was a professor and travel to Padua, where the university hired him as a professor of mathematics and he discovered a more acceptable climate for freedom of thought. He felt persecuted for challenging Aristotle.
The Moon, according to Aristotle, is a crystalline sphere orbiting the Earth in perfect circles, just like the other planets and stars.
Ptolemy adopted this idea and tried to explain the motion of the planets by artifice before reinforcing the Aristotelian notion that the Earth is the center of the universe. The Catholic Church accepts geocentrism as a true value.
With the help of his telescope, Galileo observed the Moon and discovered that it was not a perfect sphere and that the topology of its surface resembled that of the Earth.
He also became convinced of Copernicus’ theory that the Earth and the other planets revolve around the Sun because he already knew from Kepler that the motions of the planets around the Sun described ellipses.
Before geocentrism, he listed heliocentrism. Galileo was thus opposed to the official line of thought and we are aware that, for those in positions of authority, tolerance has always been an elusive ideal.
Being a scientist is just the beginning…
Galileo was not only a brilliant scientist but also a superb communicator of what he learned. He preferred to write his ideas in Italian so that many people who did not speak Latin, the scientific language of the time, could understand them.
His two most significant works, Discourses and Mathematical Demonstrations on the Two New Sciences and Dialogue on the Two Highest Systems of the World, were written as dialogues between three characters:
- Sagredo, a scholar who systematically raises valid concerns;
- Salviati, who replaces Galileo and offers the appropriate justifications and reasons;
- and Simplicio, who represents the views of the Aristotelian philosophers.
The Inquisition was forced to apply the full rigor of its law thanks to the scientific method, which relied on experience and the dissemination of its knowledge.
Claims that the Sun is the center of the world and is static and that the Earth is not the center of the world and moves were rejected by a commission of the Congregation of the Holy Office on February 24, 1616.
On March 5, 1616, the Holy Office forbids, condemns and suspends any book or teaching that speaks in the same sense and adds Nicolaus Copernicus’ De Revolutionibus to the “Index of forbidden books”, without being amended.
Forced to silence
Cardinal Robert Bellarmine warns Galileo to change his Copernican beliefs to those of the Pope. He agrees to remain silent under oath.
Perhaps he desisted because he was aware of the legend surrounding Giordano Bruno, a man who insisted that the Earth revolved around the Sun and was later killed at the stake for his heresy.
Finally, in 1624 he published the book he purported to call Dialogue on the Tides, which discussed the theories expounded by Ptolemy and Copernicus on this fact.
The book was approved by the censors of the Catholic Church in Rome in 1630, but the title was changed to Dialogue on the Two Higher Systems of the World. Immediately, the Inquisition sent him a summons to Rome to face charges of “grave suspicion of heresy.”
Galileo presented his arguments in favor of the Copernican system – which challenges the Ptolemaic system – as if it were a simple mathematical theory of planetary motions. However, this ruse was not enough to avoid his punishment.
Threat of torture
Galileo was subjected to a threat of torture when the Pope decided to have him examined on June 16, 1633. He then had to deny the alleged heresy in front of the entire Congregation of the Holy Office before being punished for breaking his oath.
Galileo had powerful friends, so, like many corrupt politicians today, he was imprisoned, but he did not lead a good life. On March 6, 1638, he finished Mathematical Considerations and Demonstrations on Two New Sciences, before returning to his wanderings and writing another exceptional book.
For this reason, several historians of science disagree with the idea that, after kneeling to declare his abjuration, Galileo got up after being condemned and stomped on the ground while shouting “eppur si muove” (“nevertheless, it moves”).
His last work was blinded before it was published and passed to the Congregation of the Holy Office, but on January 8, 1642, he began to live forever.
After 350 years of asking forgiveness for the sins of his ancestors, the Catholic Church finally received him in 1992, when John Paul II publicly atoned Galileo’s errors in October of that year.
With information from Professor-Researcher Diego Arias Serna
PhD in Physics, Universidad Complutense de Madrid and Professor-Researcher, Universidad del Quindío.