Professor of the History of Science
Propaedeutic Exam, Technical Physics, Technical University of Twente (Netherlands),1978
Doctoraalexamen [Master's degree] in History, University of Utrecht (Netherlands), 1984
Ph.D., Science and Arts [Wetenschappen], University of Utrecht (Netherlands), 1991
I have worked on a wide array of subjects, but my main topic is early modern natural philosophy. Whereas traditional histories of science tend to focus on the important discoveries and theoretical breakthroughs, with Copernicus, Kepler, Galileo, and Newton as the main beacons along the course, I am more interested in changes in the underlying assumptions. Modern science, in a self-evident way, sees nature as homogenous, causal and regulated by universal laws. However, this approach has only developed as the result of a long and twisted process. The adoption of such underlying assumptions is arguably of more importance for modern science than the development of theories or experimental methods themselves.
The modern approach to nature first got its hold on people's minds with the emergence of the "mechanical philosophy" in the seventeenth century. The central figure here is René Descartes, who first formulated a viable natural philosophy that could compete with the up to then dominant Aristotelian philosophy. Once formulated, the mechanical ideas were applied to such diverse fields as physics, physiology, astronomy or chemistry. Although the specific theories of the mechanical philosophers were in many cases untenable and had to be transformed, their general philosophical presuppositions were not seriously doubted any more and became the foundation for all later research on nature. Newton refuted Descartes' physics, but still lived in a world created by Descartes. In studying this transformation of the sciences under the impact of the new mechanical ideas, I focused in particular on cosmology and on the work of Christiaan Huygens.
If our present basic understanding of nature is not self-evident, the question is how these ideas came to be formulated in the first place. Therefore, I am not just interested in the way the mechanical ideas transformed scientific theory and practice from the middle of the seventeenth century onward, but also in what happened to natural philosophy in the period just before the rise of the mechanical philosophy, that is, in the late sixteenth and early seventeenth centuries. In that period, there was growing uncertainty about the correct understanding of nature. Aristotelianism increasingly lost favour, mathematical practice became more prominent, and all kind of would-be innovators proposed daring ideas. As nobody knew what the outcome of events would be, nobody could tell what ideas made sense and which were simply crazy, which makes this a fascinating episode to study. My research on this period focuses on discussions on cosmology and the constitution of the universe, and on ideas on the earth as they were presented in what at the time was called "meteorology" (not to be confused with the present discipline of the same name), a field which only recently has started to attract the attention of historians of science.
I am teaching especially the sciences of the earlier period, up to about 1700. I normally give the students a lot of primary sources (in English translation) to read: texts by Aristotle, Copernicus, Galileo, Descartes and others. Instead of memorizing facts, students have to come to grips with those writings. Even although I select non-technical texts, this is not easy, as these texts are not just old, but also come from foreign cultures and their way of reasoning is often unfamiliar. However, for students who want to take the effort, this is a rewarding way of getting some real historical understanding.