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)

Recent literature has explored at some length the transition between individual observations and the experimental facts that they are supposed to establish, emphasizing particularly the social dimension of this question. In this article I examine some crucial stages in the history of this problem, in particular, the way in which the establishment of experimental facts became social. I begin with a brief discussion of experimental facthood in late Renaissance thought before turning to Bacon and Descartes and showing the extent to (...) which their conception of experimental facthood is radically individualistic. I then discuss the self-consciously social conception of experimental facthood found in the writings of the early Royal Society. After a digression about some recent issues concerning the rhetoric of scientific experiments in the period, I end with some speculations about why the transition occurred when it did. The transformation in the philosophical view about the role of community in the establishment of experimental facts, I suggest, is closely connected with the emergence of a community entitled to make the judgments necessary to establish such facts. (shrink)

Much ado has been made regarding Descartes's understanding of the creation of what he called the "eternal truths" because he described them, paradoxically, as both the free creations of God, and necessary. While there are many varying interpretations of Cartesian modality, the issue has heretofore been treated in a vacuum, as a niche issue having little import beyond being an interesting puzzle for Descartes Scholars. I argue that this treatment is misguided, and that in order to properly understand Cartesian philosophy (...) at all, one must properly understand Descartes's theory of modality. This, however, is no small feat; in order to understand Descartes's seemingly peculiar view on modality, one must first make sense of what Descartes understood the nature of God to be. One reason for this, I argue, is the systematic nature of Cartesian philosophy; indeed when dealing with a dense inter-connection of philosophical issues, one must move from what is more known in itself to what is more known to us, and not the other way around. I argue that in the literature on Cartesian modality, insufficient attention has been paid to the influence of the French School of Spirituality on the Cartesian notion of the divine. I argue that this influence pushed Descartes to criticize traditional attempts to split the horns of Plato's Euthyphro dilemma as violating a proper understanding of the doctrine of divine simplicity. Descartes's commitment to a radical form of the doctrine of divine simplicity leads him to a version of divine voluntarism wherein all `things' depend on God for their existence, and God cannot have had antecedent reason to prefer the creation of anything over anything else. There is little doubt that Descartes embraced the voluntarist horn of the Euthyphro dilemma, but just what that means for Cartesian modality and philosophy generally remains a contentious issue. I argue that Descartes is best read as what I call an `agnostic quietist' regarding God given textual, historical, and systematic considerations. One virtue of an agnostic quietist reading is that I am able to square the passages where Descartes discusses the inconceivability of God's power with the conclusions reached regarding God's non-deceiving nature in the Meditations and elsewhere. Further virtues that I explore are the effects that a quietist reading has on the Cartesian scientific programme, the infamous mind-body problem, Descartes's seemingly inconsistent view regarding human free-will and Descartes's refusal to engage in "theology." Traditionally, Cartesian epistemology has been understood to be a purely a priori undertaking, which succumbs to deep and insurmountable problems. One of the greatest problems facing the Cartesian was the move from the mind to the world. Simon Blackburn, for example, says of the Cartesian epistemological project in the Meditations that Descartes "has put himself on a desert island from which there is no escape." This view is echoed by, and even motivates some of the contemporary views concerning Cartesian modality. I argue, however, that a proper understanding of the Cartesian doctrine of clear and distinct ideas circumvents this famous problem. By highlighting the proper understanding and application of the doctrine of clear and distinct ideas, I show that such ideas not only guarantee the existence of an external truth-maker, but also that such ideas do not do much more than show that there is a truth-maker. I argue that in instances of clear and distinct perception, the truth of the idea is normatively certain, but what makes it true is yet to be established. In this way, clear and distinct ideas are both powerful, in terms of guaranteeing truth, and relatively unhelpful, in that further work is required in order to determine to what the ideas conform. I argue that this is the case not only for actual truths, but for some clearly intuited truths about possibility. As an illustration of my overall thesis, I address the Cartesian argument for the separability of mind and body, and entertain the various interpretations of Descartes's view of human freedom. I argue that in order to understand Cartesian views on either of these issues, one must first make sense of his modal commitments. In both of these cases Descartes claims that finite minds can know that something is possible, even though what makes it possible is well beyond what they can understand. (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)

Summary Descartes's model for the invisible world has long seemed confined to explanations of known phenomena, with little if anything to offer concerning the empirical investigation of novel processes. Although he did perform experiments, the links between them and the Cartesian model remain difficult to pin down, not least because there are so very few. Indeed, the only account that Descartes ever developed which invokes his model in relation to both quantitative implications and to experiments is the one that he (...) provided for the rainbow. There he described in considerable detail the appearances of colours generated by means of prisms in specific circumstances. We have reproduced these experiments with careful attention to Descartes's requirements. The results provide considerable insight into the otherwise fractured character of his printed discovery narrative. By combining reproduction with attention to the rhetorical structure of Descartes's presentation, we can show that he worked his model in conjunction with experiments to reach a fully quantitative account of the rainbow, including its colours as well as its geometry. In this one instance at least, Descartes produced just the sort of explanatory novelties that the young Newton later did in optics. That Descartes's results in respect to colour are in hindsight specious is of course irrelevant. (shrink)