One of the great accomplishments of human thought has been the development of Newtonian mechanics, our modern understanding of the role of inertia, acceleration, and gravity, the science of motion. As Newton acknowledged, his insights built on the work of many others. Galileo was one of the foremost. But the progression from Aristotle through Galileo to Newton was never as simple and direct as a relay race. Galileo himself was often mistaken, even more often misunderstood or misinterpreted. Complicating the task of understanding his role in this development is the fact that Galileo’s own understanding of motion evolved over the course of his life.
This volume explores many aspects of Galileo’s science of motion, how it was interpreted and used, and the role it played in the development of the modern understanding of motion. There are two dominant themes to this work. The first is the concept of the “mechanization” of our understanding of the world, a term that appears repeatedly in 17th century texts and that was driven into our modern interpretation of this era by E.J. Dijksterhuis’ now classic history of the progression leading to Newtonian mechanics, The Mechanization of the World Picture. Yet as Alan Gabbey argues in the first article of this collection, the term “mechanical,” applied to the science of Galileo and Descartes, is anachronistic. This word does not enter scientific self-description until Robert Boyle who first employs it in this modern sense in 1661. Sophie Roux counters that Descartes was very much aware of his approach as one of mechanization. She explores the self-contradictions and difficulties within Descartes’ attempt to provide mechanical explanations.
The other dominant theme is the conflict between the views and methods of Galileo and Descartes, what Dijksterhuis described as the conflict between “the modesty of mathematical-physical method and the arrogance of philosophical thought.” In his article, Floris Cohen identifies these approaches to scientific knowledge as “Alexandria-plus,” aimed at describing phenomena in mathematical terms, and “Athens-plus,” aimed at general explanations based on first principles. Cohen describes the difficulties Galileo faced in introducing his quantitative approach to scientific study and argues that the ultimate triumph of the Alexandrian-plus approach was not inevitable.
The next article delves into Galileo’s unpublished manuscripts, using them to demonstrate that Galileo’s understanding of motion was never clear and unambiguous. This is followed by an analysis of the work of Galileo’s students for a further expansion on Galileo’s own thoughts on motion. There are then separate articles on how Galileo’s work influenced that of Gassendi, Hobbes, Huygens, and Varignon. There is also a fascinating article on how the science of motion in its various 17th century manifestations played out in explanations of the tides.
In sum, this volume is accessible and interesting. It is not suitable as an introduction to the history of the development of the science of motion in the 17th century, but for those who know something of this story and are intrigued to learn more, it is a wonderful and thought-provoking collection.
David M. Bressoud is DeWitt Wallace Professor Mathematics at Macalester College in St. Paul, Minnesota.