IT is still possible to find histories of science that describe the achievements of the ancient Greeks and then pass immediately to the Renaissance, with perhaps a brief remark about the absence of any developments worth mentioning in the intervening period. That such slighting of the contributions of the medieval philosophers is no longer acceptable in any work with pretensions to scholarship is mainly due to the work of one man, the French physicist Pierre Duhem.
Duhem was born in Paris in 1861, and studied at the College Stanislaus and the Ecole Normale. While still in his second year, he submitted a doctoral thesis on thermodynamics, which unfortunately contradicted (correctly as it appeared later) a favourite principle of the chemist Berthelot, a powerful figure in the French academic establishment. Not only did Berthelot ensure that the thesis was rejected, but he declared that Duhem would never teach in Paris. It did not take Duhem long to write another thesis of a more mathematical nature that was accepted by different examiners, but his career was permanently blighted by his clash with Berthelot.
In his first thesis Duhem had shown the usefulness of the concept of thermodynamic potential, and he deduced what is now known as the Gibbs-Duhem equation. In the following years he consolidated his scientific reputation, working on the interaction of electric currents, and the theory of saline solutions as well as making a rigorous analysis of the foundations of thermodynamics.
His first academic appointment was to a lectureship in Lille, where he won praise for the excellence of his teaching and his devotion to his students. His lecture notes were so clearly written and logically presented that they were soon published in a series of volumes. His scientific reputation continued to grow, but because of the hostile attitude of the authorities he was not called to Paris. Instead he was obliged to move first to Rennes and then to Bordeaux, where he spent the remainder of his life.
At that time French physics was at a low ebb, lacking the theoreticians to develop general theories and use them to unify the increasing mass of experimental data. Duhem could have been one of the leaders in this work, and indeed felt it to be his patriotic duty, but because of his banishment from Paris he spent much of his life giving advanced lecture courses to largely empty benches.
Many of Duhem's ideas in physics were far in advance of his time, and have some similarities to those of the new physics. He had always been interested in the development of scientific ideas, and read widely in the history of mechanics. He was asked to write a series of articles on this subject, and meticulously followed the story from the Renaissance back to its medieval roots. During these studies he gradually became aware of the continuous development throughout the Middle Ages that culminated in the achievements of Galileo and Newton. He studied in detail the works of Leonardo da Vinci, and found that he obtained many of his ideas from the medieval thinkers. Gradually there opened up before Duhem's astonished eyes the real story of the development of science, so different from the familiar tale of unbroken intellectual darkness between the Greeks and the Renaissance. There was, as the documents he uncovered showed, intense intellectual activity during the Middle Ages, and a leading part was played by the masters of the Paris schools, in particular by Jean Buridan and Nicholas Oresme.
At that time the ideas of the nature of the world were mainly derived from Aristotle. The philosophers of the Parisian schools taught by commenting on his texts. Some of Aristotle's teaching, however, was inconsistent with the Christian faith, and the Parisian philosophers did not hesitate to differ from him whenever this seemed to be necessary. There was intense discussion on a variety of topics notably concerning the creation of the …