Galileo's condemnation: The real and complex story

ABSTRACT

Often the Catholic Church's condemnation of Galileo Galilei is viewed as the prime example of an ongoing "war" between science and religion. Just as often the reason for this condemnation is thought to be Galileo's advocacy of Copernicanism. The true story is much more complex than these assumptions. Firstly, modern historians of science do not accept the "warfare" thesis of science versus religion. Secondly, Galileo's claim that each planet orbits an imaginary point that, in turn, orbits another imaginary point near the sun, may not have been the root cause of his troubles with the Church. The reasons behind Galileo's sentence are complex. There are several factors besides Copernicanism. One is angering his friend, Pope Urban VIII. Recent documentary discoveries indicate that another factor was Galileo's advocacy of atomism, which undermined the Church's scientific understanding of the Eucharist.

Key words: Galileo Galilei, Copernicanism, Atomism, Eucharist, Popes Paul V and Urban VIII, Cardinal Robert Bellarmine, Johann Kepler

INTRODUCTION

A pervasive idea in much of our culture is that science and religion inherently conflict with one another. However, most modern historians of science do not share that idea. For them, this claim is unsupported and dated (1). Similarly, the popular cultural view of Galileo's treatment at the hands of the Catholic Church is often distorted. This article analyzes the interaction of Galileo, science, and the Church, and shows just how complex it was.

Historians and Galileo

Of the books and analyses of Galileo Galilei's condemnation, one of the most interesting is Pietro Redondi's Galileo: Heretic (1987) (2). In 1982, Redondi discovered a document, labeled "G3," which contains an accusation concerning Galileo's atomism (3). The danger of atomism in Galileo's time was that it conflicted with the Church's Aristotelian explanation for the Eucharist in which bread and wine miraculously turn into the body and blood of Jesus Christ. Catholic theologians used Aristotle's physics to explain that, while the substance of the bread and wine changes, the qualities do not. This scientifically-based idea became Church dogma, and therefore could not be questioned without challenging the Church's authority. Basically, Redondi argues that the promotion of atomism and its threat to the Church was the real reason for Galileo's condemnation. Copernicanism merely was the cover for it.

Historians of science did not readily accept Redondi's theory when he proposed it in the 1980's. This included the excellent one I studied under, the late Richard Westfall. He pointed out that the last mention of atomism was in Galileo's Assayer, published in 1623, but Galileo's condemnation occurred a decade later in 1633. The timing did not seem to fit. This rationale however, has been counted by the discovery, in November 1999, of a new document in the same archive as G3, labeled EE291. It is a working paper that discussed the charge of atomism against Galileo. Handwriting analysis indicates that a member of a special commission the pope formed to investigate Galileo wrote it in 1632 (4).

I conclude from the new evidence that the atomism charge was one of many factors that led to Galileo's condemnation. The other factors were that Galileo was obsessed with Copernicanism as the actual structure of our Solar System, appeared to have disobeyed an injunction, made a number of enemies who were more influential than he thought, was insensitive to the current political situation, advocated his personal interpretation of the Bible against Catholic authorities, and antagonized his friend, the pope.

In spite of the above, what we tend to hear is that Galileo's scientific stance on Copernicanism that was the basis of his condemnation. So let us look at the scientific background, starting with the structure of the universe.

The Structure of the Universe

Early Greek philosophers, like many thinkers before them, gazed into the night sky and decided it appeared to be shaped like a dome, a hemisphere. They concluded that the entire shape of the starry heaven is spherical. They came to think of the stars as attached to the sphere. As this giant orb rotated around a stationary earth, the stars traced out circular paths, which were thought to be perfect motion. One exception was the Pythagorean idea that the earth moved. Aristotle attacked this idea and instead worked out a geocentric system of more than fifty rotating and counter rotating crystalline spheres. His machinery caused the sun, moon, planets and stars to move "perfectly," that is, in unchanging circular courses. Aristotle's science was so comprehensive that it came to dominate intellectual thought up to the Scientific Revolution.

As astronomers gathered more data, they realized that they needed new explanations to account for the observed paths in the sky. Claudius Ptolemy (2nd century A.D.) answered this growing problem with a system of epicycles, equants, and eccentrics that accounted for appearances. Still, he preserved Aristotle's circular motion as seen in Figure 1. This system worked wonderfully for predicting future planetary positions and calculating past ones, but is it scientifically real (5)? Does each planet actually circle its own imaginary point in space, and does this imaginary point circle yet another imaginary point in space? This second center of circular motion is offset from a motionless earth and is called the eccentric. Thus the correct name for Ptolemy's system is not geocentric, as it is usually called, but geostatic.