At various points in his work on physiology and medicine, Descartes refers to a “principle of life.” The exact term changes—sometimes, it is the “principle of movement and life”, sometimes the “principle underlying all [the] functions” of the body —but the message seems consistent: the phenomena of living bodies are the product of a single, underlying principle. That principle is generally taken to be cardiac heat.1 The literature has, quite reasonably, taken this message at face value. Thus, Shapiro: “Descartes insists (...) again and again that the human body is properly to be described as a machine whose workings are […] driven by the heat in the heart that... (shrink)

Descartes’s most extensive discussion of the law of refraction and the shape of the anaclastic lens is contained in Rule 8 of "Rules for the Direction of the Mind". Few reconstructions of Descartes’s discovery of the law of refraction take Rule 8 as their basis. In Rule 8, Descartes denies that the law of refraction can be discovered by purely mathematical means, and he requires that the law of refraction be deduced from physical principles about natural power or force, the (...) nature of the action of light, and the behavior of light rays in a variety of transparent media. For over a century, however, there has been broad agreement that Descartes discovered the law of refraction by purely mathematical means, and that he only later provided the relevant physical rationale (via comparisons or analogies) in Dioptrics II. I execute each step in Descartes’s proposed deduction of the law of refraction and the shape of the anaclastic lens in Rule 8 and concretely show how Descartes could have discovered the law of refraction and the shape of the anaclastic by its means. Rule 8, I argue, reflects Descartes’s actual path to the discovery of the law of refraction and the shape of the anaclastic lens. (shrink)

This paper presents a new approach to resolving an apparent tension in Descartes’ discussion of scientific theories and explanations in the Principles of Philosophy. On the one hand, Descartes repeatedly claims that any theories presented in science must be certain and indubitable. On the other hand, Descartes himself presents an astonishing number of speculative explanations of various scientific phenomena. In response to this tension, commentators have suggested that Descartes changed his mind about scientific theories having to be certain and indubitable, (...) that he lacked the conceptual resources to describe the appropriate epistemic attitude towards speculative theories, or that the presence of geometrical principles in these explanations guarantee their certainty. I argue that none of these responses is satisfactory and suggest a different resolution to the tension by examining Descartes’ notion of explanation. On Descartes’ view, providing an adequate explanation does not require being certain of the theories that constitute the explanans. Relatedly, the purpose of Cartesian explanations is not to discover the truth about the various underlying mechanisms that such explanations appeal to, but to support his general philosophical thesis that all natural phenomena can be explained by appealing to the extension of matter. (shrink)

Bei den korpuskulartheoretischen Erklärungen von Naturphänomenen, wie sie Descartes in den Principia philosophiae vornimmt und im Discours de la methode anspricht, lassen sich zwei verschiedene und nur teilweise miteinander vereinbare Bedeutungsgruppen des Hypothesenbegriffs nachweisen. Sie verbinden sich mit unterschiedlichen Bewertungen des Status von Hypothesen im wissenschaftlichen Erkenntnisprozeß. Einerseits findet man eine Verwandtschaft zum heute wissenschaftstheoretisch verbreiteten Verständnis von Hypothesen als positivem und integralem Bestandteil der Naturerkenntnis. Typischer für Descartes' Naturphilosophie ist jedoch die andererseits von ihm vertretene Vorstellung, daß der Umfang (...) des bloß hypothetischen Wissens im Fortgang der Naturerkenntnis zu minimieren sei. Mit dieser Forderung erweist sich Descartes als Vertreter einer neuzeitlichen Wissenschaftsauffassung, die deutlich vom modernen Verzicht auf ein ausschließlich geltendes System der Naturerkenntnis abgehoben ist. (shrink)

In 1675, Burchard de Volder (1643–1709) was the first professor to introduce the demonstration of experiment into a university physics course and built the Leiden Physics Theatre to accommodate this new pedagogy. When he requested the funds from the university to build the facility, he claimed that the performance of experiments would demonstrate the “truth and certainty” of the postulates of theoretical physics. Such a claim is interesting given de Volder’s lifelong commitment to Cartesian scientia. This chapter will examine de (...) Volder’s views on experiment and show that they are not Newtonian or inductivist, as is sometimes claimed. While de Volder thinks we need deductive reasoning from first principles to provide evidence of the certainty of the content of our physical theories, he also contends that we need experiment to provide evidence of the certainty of the existence of the particular bodies those theories discuss. This approach to experiment is based on a distinction between rational certainty and the certainty of material bodies in the actual world. While this account is deeply influenced by Descartes, it is importantly different than Descartes’ distinction between absolute and moral certainty. De Volder’s “Cartesian Empiricism” is best understood as a continuation and further development of a long tradition of teaching through observation at Leiden. (shrink)

Descartes is usually taken to be a strict reductionist, and he frequently describes his work in reductionist terms. This dissertation, however, makes the case that he is a nonreductionist in certain areas of his philosophy and natural philosophy. This might seem like simple inconsistency, or a mismatch between Descartes's ambitions and his achievements. I argue that here it is more than that: nonreductionism is compatible with his wider commitments, and allowing for irreducibles increases the explanatory power of his system. Moreover, (...) Descartes depends on nonreductionist knowledge and on irreducibles in order to maintain his epistemology and metaphysics. That is, there is more in the Cartesian world than mind, matter, and God. (shrink)

Descartes was both metaphysician and natural philosopher. He used his metaphysics to ground portions of his physics. However, as should be a commonplace but is not, he did not think he could spin all of his physics out of his metaphysics a priori, and in fact he both emphasized the need for appeals to experience in his methodological remarks on philosophizing about nature and constantly appealed to experience in describing his own philosophy of nature. During the 1630s, he offered empirical (...) support for the basic principles of his natural philosophy, while also promising to provide a metaphysical justification. He offered the metaphysical justification in the Meditations and Principles. and claimed absolute certainty for it. At the same time, he recognized that the particular postulated mechanisms of his natural philosophy did not reach that standard of certainty. These mechanisms were supported by empirical testing or confirming of causes through observed effects. (shrink)