In their book on Descartes’s changing mind, Peter Machamer and J.E McGuire argue that Descartes discarded dualism to embrace a kind of monism. It is intriguing to investigate if the master of dualism could have changed his mind about the central aspect of his system. After reviewing the position of the authors, we will consider how and in what terms Descartes did not go back on his favorite doctrine but may have fooled himself about the nature of his dualism. It (...) is my contention that the so-called problematic Cartesian dualism has its origin in the lack of proper definition of mind and body as substances and the role of their respective attributes, thought and extension in the definition of the substances. The main answer to Machamer and McGuire’s thesis is that Descartes could develop his epistemology of mind and body independently of a metaphysics of substance and its attributes. In other words not only did Descartes not change his mind, but he persevered and enriched his dualist metaphysics. The subsidiary answer to the authors is that the concessions given by Descartes to the opponents of his dualism can be found in earlier works, but, pace the authors, they did not cause him not to develop his dualism in the first place. (shrink)

According to Kepler and Descartes, the geometry of the triangle formed by the two eyes when focused on a single point affords perception of the distance to that point. Kepler characterized the processes involved as associative learning. Descartes described the processes as a “ natural geometry.” Many interpreters have Descartes holding that perceivers calculate the distance to the focal point using angle-side-angle, calculations that are reduced to unnoticed mental habits in adult vision. This article offers a purely psychophysiological interpretation of (...) Descartes’s natural geometry. In his account of perceived limb position from the Treatise on Man, he envisioned a central brain state that controls ocular convergence and thereby co-varies with the distance from observer to object. A psychophysiological law relates the visual perception of distance to this brain state. Descartes also invokes more traditional theories of distance and size perception based on unnoticed judgments, yielding a hybrid account. (shrink)

In this article I dispute the claim, made by several contemporary scholars, that Spinoza was a naturalist. ‘Naturalism’ here refers to two distinct but related positions in contemporary philosophy. The first, ontological naturalism, is the view that everything that exists possesses a certain character permitting it to be defined as natural and prohibiting it from being defined as supernatural. I argue that the only definition of ontological naturalism that could be legitimately applied to Spinoza's philosophy is so unrestrictive as to (...) tell us nothing about the content of his ideas. The second, methodological naturalism, is the view that the natural sciences are the best means of finding out substantial truths about the concrete world. I present some historical research showing that Spinoza's way of positioning himself with respect to other philosophers in the Dutch Republic casts very serious doubt on the claim that he was a methodological naturalist. This adds further weight to arguments that have already been made against the naturalist reading of Spinoza. (shrink)

This essay offers an interpretation of Descartes’ treatment of the concepts of place and space in the Principles of Philosophy. On the basis of that interpretation, I argue that his understanding and application of the concept of space supports a pluralist interpretation of Descartes on extended substance. I survey the Scholastic evolution of issues in the Aristotelian theory of place and clarify elements of Descartes’ appropriation and transformation thereof: the relationship between internal and external place, the precise content of the (...) claim that space and body are really identical, and the way we conceptually distinguish space from body. Descartes applies his concept of space in ways that illuminate the metaphysical structure of extension. In particular, he uses the concept to specify the degree to which finite parts of matter are independent of each other. I argue that for Descartes, conceiving extension as indivisible is an artifact of conceiving it as a space. That is, pace the monistic reading of Cartesian extended substance, regarding extension as indivisible is an artifact of conceiving it in a way more removed from its real nature. (shrink)