The Scientific Revolution

Lesson 5: The New Philosophers

Galileo

Galileo Galilei, one of the greatest minds of the scientific revolution, also lived one of the most dramatic lives. After entering the University of Pisa in 1581 as a medical student, Galileo discovered mathematics and promptly became enraptured.

He supplemented classes in natural philosophy at Pisa with private mathematical study in Florence. He became a mathematics tutor in Florence, where he established the isochronous nature of the pendulum – the fact that the frequency of a pendulum is a constant. In 1592, Galileo became Professor of Mathematics at Padua. He later described the Padua years as the best of his life despite his inadequate salary. At Padua, Galileo moved from a highly mathematical approach to knowledge to a greater interest in experiment, although the story of his dropping balls from the Leaning Tower of Pisa is only a legend.

Galileo was a convinced and vociferous opponent of Aristotelian physics. He began to elaborate a non-Aristotelian approach to the problems of moving bodies. His most famous result was the law of falling bodies, that the distance covered by a falling body varies with the square of the time of the fall.

Galileo introduced into mechanics the idea of uniform acceleration and made the first steps towards formulating the principle of inertia. Although astronomy was not a major interest at this time, Galileo was clearly a discreet Copernican who began corresponding with Johannes Kepler in 1597. What catapulted this obscure, if well-respected, university professor to Italian and European fame were his telescopic discoveries – the moons of Jupiter, the phases of Venus, and the composition of the Milky Way out of innumerable stars. These epochal discoveries were anounced in The Starry Messenger [Nuncius Sidereus] (1610).

The naming of Jupiter’s moons the Medicean stars after the ruling dynasty of Tuscany was a brilliant stroke which secured Galileo’s appointment as court mathematician. Galileo insisted that he be given the title not merely of mathematician, but philosopher as well.

Since the actual physical nature of the universe was the province of natural philosophers, Galileo as a philosopher could make claims about the nature of the universe that he could not make as a university mathematician. Galileo’s move to the Tuscan court helped him address a wider audience in Italian rather than Latin.

Galileo was a skillful courtier and a merciless debater who made many enemies. His anti-Aristotelian Discourse on Floating Bodies (1612) originated in a conversation at the Duke’s table. The Florentine court was connected to the Papacy’s; in 1611 Galileo was admitted to the Accademia dei Lincei, a Roman scientific society led by Federico Cesi. It was from Rome that Galileo faced the greatest challenge of his career, that of the church’s condemnation of Copernicanism. His pro-Copernican Letters on Sunspots (1613), arguing that they were indeed spots on the sun, led to a bitter dispute with the Jesuit astronomer Christoph Scheiner (1573-1650), who believed (although he later changed his opinion) that the spots were celestial bodies between the sun and the earth.

Galileo’s relations with the Jesuits had up to this time been not particularly hostile, but the Order and Scheiner in particular became bitter enemies. On a general level, Church authorities took an increasingly repressive attitude toward Copernicanism and Galileo as its principal Catholic champion, putting Copernicus’s On the Revolution of the Heavenly Spheres on the Index of Forbidden Books in 1616.

Unlike Kepler and Newton, among others, Galileo always pursued science as something separate from religion. He argued that Copernicanism was a purely philosophical concept having no bearing on theology, but was defeated. Galileo was powerful and well-connected, though, and his works were not specifically condemned. Galileo’s statement of his beliefs about science and religion are included in Oster’s document 4.1, along with those of Cardinal Robert Bellarmine. How do Galileo’s and Bellarmine’s positions differ?

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