The Routledge Guidebook to Galileo’s Dialogue by Maurice A. Finocchiaro (review)

Most of Maurice Finocchiaro’s distinguished career has been devoted to a close and detailed study of Galileo Galilei. In Galileo and the Art of Reasoning (Boston, 1980), he commented on his use of logic and various forms of argument in the Dialogue on the Two Chief World Systems (1632), and in Retrying Galileo, 1633–1992 (Berkeley, 2005), he examined the documents and the issues concerning Galileo’s trial, which also was about the book that created the stir. In this guidebook to Galileo’s Dialogue, he offers an extended reconstruction of this great work and provides an extended analysis of the intellectual background and the historical context of the Copernican controversy. Finocchiaro describes in a lucid and rigorous way the arguments and critiques that Galileo presented in the Dialogue, and he assesses the content and the significance of the book from three special points of view: science, methodology, and rhetoric. The main argument of the book is a reconstruction of Galileo’s argument in favor of the Earth’s motion. Finoc-chiaro remains faithful to the original and retains the Dialogue’s basic structure and topical progression, but he also elucidates what is obscure, resolves ambiguities, and makes explicit the hidden assumptions. The reconstruction is sufficiently detailed not to miss anything essential yet sufficiently streamlined to avoid the digressions that Galileo occasionally allowed himself.

To confirm the Copernican hypothesis, Galileo used a twofold approach. On the one hand, he defended the motion of the Earth from numerous objections based on Aristotelian physics, naked-eye astronomical observations, and traditional epistemology. On the other hand, he supported heliocentrism with arguments stemming from his new physics, telescopic observation, and the methodological analysis of contextualized philosophical problems. The Dialogue triggered Galileo’s trial that ended with the condemnation and banning of the book. Publication had been problematic in the light of a series of events that began in 1613, and Finocchiaro explains the subsequent developments until the trial that was held in Rome in 1633.

The condemnation of the Dialogue gave rise to a controversy that continues to the present day. The prolonged debate revolves around issues raised at the original trial, but also involves new questions such as whether the condemnation of Galileo was right or wrong, whether it shows the incompatibility between science and religion, and whether something can be learned from it regarding the interaction between individual freedom and institutional authority. Finocchiaro addresses these concerns with an open mind. He emphasizes Galileo’s rhetorical gifts, which involve such forms and techniques of persuasive argumentation as eloquent expression, imaginative portrayal, emotional description, nuanced assertion, repetition, double entendre, wit, satire, humor, and ridicule. But this should not be taken as implying that he equates rhetoric with the art of deception or skill at making the weaker argument appears the stronger. The wealth of the book’s rhetoric also derives from the fact that Galileo was addressing several audiences at the same time and from his choice of the dialogue form, which means that there is a certain amount of drama unfolding before the eyes of the reader.

This scholarly introduction to Galileo’s achievements will be welcomed by anyone teaching the history of science or simply curious about how we came to know that the Earth is in motion.