What To Do With Seventeenth-Century Natural Philosophy? A Taxonomic Problem1 Christoph Lüthy University of Nijmegen The issue at stake According to our history books, modern philosophy and modern science were both born in the seventeenth century. If this was merely a matter of temporal coincidence, there would be nothing remarkable about it. But the two phenomena appear to be connected: historians of philosophy and historians of science do not only look to the same time period for the birth date of their respective modern histories, but they often look to the same people and in some cases even to the same texts. What are the implications of this overlap?If the history of philosophy and the history of science could be so completely mapped upon each other as to appear as one identical enterprise, this would constitute a lesser prob- lem. It would then sufªce to explain how it came that two enterprises that today are quite distinct pursuits joined hands for a certain period. But the problem is much more vexing than that: while it is generally understood that the redeªnition of philosophy and the birth of modern scientiªc methods are linked phenomena, no one has ever taken them to constitute identical enterprises. At the same time, the type of link between the two 1. This essay deals mainly with the following two publications: 1) Daniel Garber and Michael Ayers, eds., Cambridge History of Seventeenth-Century Philosophy (1998), here abbre- viated as Cambridge History; 2) Jean-Pierre Schobinger, ed., Grundriss der Greschichte der Philosophie begründet von Friedrich Ueberweg. Die Philosophie des 17. Jahrhunderts. Band 1: Allgemeine Themen. Iberische Halbinsel/Italien (1998), here abbreviated as Ueberweg. In a less systematic manner, it also takes into consideration: 3) G.H.R. Parkinson, ed., Routledge History of Philosophy. Vol. IV: The Renaissance and Seventeenth-Century Rationalism (1993), here abbreviated as Routledge History; 4) Lothar Kreimendahl, ed., Philosophen des 17. Jahrhunderts. Eine Einführung (1999), here abbreviated as Philosophen; and 5) Edward Graig, ed., Routledge Encyclopedia of Philosophy (1998), here abbreviated as Routledge Encyclopedia. I should like to thank Carla Rita Palmerino, Cees Leijenhorst and Hans Thijssen for their useful comments and suggestions on drafts of this paper. Perspectives on Science 2000, vol. 8, no. 2 ©2000 by The Massachusetts Institute of Technology 164 Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/106361400568064 by guest on 01 October 2021 Perspectives on Science 165 phenomena continues to be debated. Must we assume the existence of an essential bond between the two, or did the development in one ªeld trig- ger a revolution in the other? One of the main keys to the understanding of the nature of this puzzle lies with natural philosophy and with the enormous growth and reorien- tation of this discipline in the seventeenth century. Natural philosophy had for centuries been a bookish discipline without nature (John Murdoch 1982) and, while being empiricist in nature, had proceeded without observations (Edward Grant 2001). It had sought solutions to conceptual riddles and seeming inconsistencies found primarily in Aris- totles libri naturales and in the commentary tradition these texts had en- gendered. When speaking of medieval science, careful historians there- fore distinguish between the philosophical and propedeutic discipline of natural philosophy, on the one hand, and those various other activities that must be mentioned among the precursors of modern scientiªc disciplines, notably medicine; certain techniques in the domains of alchemy or metal- lurgy; the quadrivial disciplines and notably astronomy; or the mixed sci- ences and speciªcally optics. With regard to the Middle Ages and the Renaissance, then, it is not too difªcult to distinguish the explicitly speculative and contemplative discipline of philosophia naturalis or physica from those other activities. However, the picture changes fundamentally in the seventeenth century. With the introduction of experimental and mathematical approaches to the study of natural phenomena, traditional differences between specula- tive thought and practice, literary study and applied labor became blurred. All kinds of non-scholastic activities came to insert themselves into the old scholastic domain of philosophia naturalis or physica, which in the process turned into a mathematical, chemical, medical, and generally empirical discipline. The confusing consequence was that everyone who was concerned with some aspect or other of the natural world came to con- sider himself ipso facto a philosopher. This immense extension of the ªeld of philosophical activity explains also why instruments such as telescopes, prisms, or vacuum pumps came to be regarded as philosophical instru- ments. Although this redeªnition of the scope of philosophy to cover ex- perimentation and observation could be (and sometimes was) celebrated as a return to the original Greek spirit of the philosophical enterprise, it ob- viously far exceeded the deªnitional boundaries of both what had previ- ously been called philosophy and what we nowadays understand by this term. This situation confronts the modern historian with a series of difªculties and not least with a problem of taxonomy. By calling philo- sophical much of what to us looks like science, the seventeenth century Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/106361400568064 by guest on 01 October 2021 166 What To Do With Seventeenth-Century Natural Philosophy? appears to snatch away from historians of science almost all that is of in- terest to them about this period. At the same time, it forces the historian of philosophy to become a historian of science. This situation explains the following comment by the editors of the Cambridge History, Michael Ayers and Daniel Garber: We have allowed some compromise between what the term philos- ophy meant then and what it means now. In the seventeenth cen- tury it was unremarkable if the same philosophers who wrote on metaphysics, logic, ethics, and political theory, on the existence of God, or on the varieties of human knowledge and belief also made contributions to mathematics, offered an account of the laws of mo- tion, peered through microscopes or telescopes, recorded the weather, conducted chemical experiments, practised medicine, in- vented machines, debated the nature of madness, or argued about church government, religious toleration, and the identity and inter- pretation of divine revelation. The present history of philosophy includes neither a history of natural science nor a history of reli- gious doctrine and practice, but much is said in it about the some- times surprising connection between theory and argument in such areas and what is more recognizably in ancestral relation to the philosophy (or philosophies) of today. One fundamental shift is reºected in the change in the sense of the word science (pp. 12). In a similar vein, the general editor of the Ueberwegs new Philosophie des 17. Jahrhunderts, Jean-Pierre Schobinger, writes in his Introduction: We must also consider the mathematical, scientiªc and medical de- velopments, for these were often accompanied by philosophical ar- gumentswhich may well constitute a peculiarity of that century. It was a phenomenon, whose frequency decreased with the rapid in- crease of knowledge in these areas, the establishment of new scien- tiªc domains and the increasingly strong experimental orientation of research (p. xliv).2 Schobingers observation seems quite correct. The seventeenth centurys experimental philosophy presents an historical anomaly which was des- tined to disappear again, though very slowly, as the consequence of the institutionalization of separate scientiªc disciplines. But because of its anomalous character, the history of seventeenth-century philosophy is par- ticularly hard to write. Despite the growing willingness to work in an in- terdisciplinary manner, it is still true that historians of philosophy tend to 2. Unless otherwise indicated, all translations are mine. Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/106361400568064 by guest on 01 October 2021 Perspectives on Science 167 leave much of natural philosophy to historians of science, while the latter deliberately ignore the philosophical embedding of their science and even a good part of what the seventeenth century called scientia, notably theology. The question therefore arises of whether the criteria by which these early modern categories are cut up and then reassembled are pre- meditated and explicit, or whether they are only the expression of the un- derstandable, but nonetheless deeply whiggish desire to ªnd a prehistory for the modern categories and disciplines. The recent publication of a number of new surveys of seventeenth- century philosophy provide a suitable occasion to review these problems and questions. In the following, I shall examine some of these works to understand how todays historians of philosophy cope with the problems of taxonomy just mentioned. However, a few general remarks are in order before we examine these works individually. A comparison of general surveys in the history of sci- ence, on the one hand, and in the history of philosophy, on the other, dem- onstrate that we are still far from seeing a convergence of the two historiographies. It appears that there exist a number of speciªc areas in which the problems involved in aligning the history of philosophy