Born in Pisa, Italy on February 15, 1564, Galileo Galilei was an astronomer, physicist, and engineer, but he had also played a key role in many histories of philosophy. He is a central figure of the Scientific Revolution of the seventeenth century. His work in physics or “natural philosophy”, astronomy, and the methodology of science still evoke debate after more than 400 years. He promoted the Copernican theory which shift from describing the cosmos as having Earth stationary at the center of the universe, to the heliocentric model with the Sun at the center of the solar systems.
Galileo was enrolled by his father Vincenzo for a medical degree at the University of Pisa in 1580. He never completed this degree, but obtained an interest in Mathematics, and pursued Mathematics with Italian mathematician Ostilio Ricci, who taught at the Florentine Accademia del Disegno. After leaving university, Galileo worked as a private mathematics tutor and was appointed lecturer in mathematics at Pisa in 1589. During this period, he began a relationship with Marina Gamba, and their daughter Virginia was born in 1600. In 1601, they had another daughter, Livia, and a son, Vincenzo, in 1606.
In 1623, Galileo published The Assayer, which includes some of Galileo’s most famous methodological pronouncements. It contains passages suggestive of atomism, a heretical doctrine, for which the book was referred to the Inquisition, which dismissed the charge.
Galileo published a Discourse on Floating Bodies and Letters on Sunspots in 1613, where he first openly expressed support for Copernican heliocentricism. He wrote a Letter to Castelli defending the doctrine from theological objections. Meanwhile, it had become known that Copernicanism was under scrutiny by Church authorities. Galileo lectured and lobbied against its condemnation, expanding his Letter to Castelli into the widely circulated Letter to the Grand Duchess Christina in 1615. Nevertheless, in March 1616, Copernicus’s On the Revolutions of the Heavenly Orbs was temporarily censored, pending correction, by the Congregation of the Index of Prohibited Books. Galileo himself was called to an audience with Cardinal Robert Bellarmine, a leading theologian and member of the Roman Inquisition, who admonished him not to teach or defend Copernican theory.
Shortly after the printing of his work Dialogue Concerning the Two Chief World Systems was completed, the Inquisition banned its sale and Galileo was ordered to Rome for trial. Galileo officially faced the Roman Inquisition in April of 1633. Roman Inquisition found him “vehemently suspect of heresy”. Galileo agreed to plead guilty in exchange for a lighter sentence by admitting that the propositions that the Sun is in the centre of the world and immovable from its place and that the Earth is not the centre of the world, nor immovable, but that it moves, and also with a diurnal motion, are absurd, philosophically false, and formally heretical; because they are expressly contrary to the Holy Scripture. He promised to relinquish altogether his “heretic” opinion and never defend or teach it in the future. He was not allowed to write any books. In the last nine years of his life, Galileo lived in a villa under comfortable house arrest. On January 8, 1642, Galileo Galilei died at age 77 after suffering from heart palpitations and a fever in Arcetri near Florence, Italy.
Machamer, Peter and David Marshall Miller, “Galileo Galilei”, The Stanford Encyclopedia of Philosophy (Summer 2021 Edition), Edward N. Zalta (ed.), URL = <https://plato.stanford.edu/archives/sum2021/entries/galileo/>.
Sterling, Bruce, “The sentence of the Inquisition on Galileo”, Wired. April 1, 2020. <https://www.wired.com/beyond-the-beyond/2020/04/sentence-inquisition-galileo/>.