This paper argues that Spinoza's notions of “conatus” and “power of acting” are derived by means of generalization from the notions of “force of motion” and “force of determination” that Spinoza discussed in his Principles of Cartesian Philosophy to account for interactions among bodies on the basis of their degrees of contrariety. I argue that in the Ethics, Spinoza's ontology entails that interactions must always be accounted for in terms of degrees of “agreement or disagreement in nature” among interacting things. (...) The notion of “power of acting” is used to express the extent to which a thing's conatus is aided or restrained by external causes on the basis of its degree of agreement or disagreement in nature with them. “Power of acting” generalizes the same approach and method of resolution at the basis of the notion of “force of determination” in order to account for causal interactions not only among the simplest bodies but also among more complex individuals. (shrink)

In this paper, I discuss Spinoza on the proper methods and content of physical science. I start by showing how Spinoza's epistemology leads him to a kind of pessimism about the prospects of empirical and mathematical methods in natural philosophy. While they are useful for life, they do not tell us about nature, as Spinoza puts it, “as it is in itself.” At the same time, Spinoza seems to allow that we have some knowledge of physical things and their behavior. (...) So I go on to outline and critique a few of the accounts of how Spinoza thinks we can do this, focusing on the role of the common notions in physics. In the third section, I discuss the possible contents of physics, for Spinoza, and argue that they are not, as is usually thought, fundamentally Cartesian. I conclude by pointing to some promising directions for future research and suggesting a few heuristics for such research. (shrink)

This article concerns the notion of living bodies that Spinoza develops in the Ethics (published posthumously in 1677). While commentators have emphasized the relevance of Spinoza’s works for contemporary physiology, they have neglected to study Spinoza’s own views on this topic. My aim is to draw attention to the specific parti pris that underlies Spinoza’s passages on anatomy. To do so, I first compare Spinoza’s claims on human body with the conceptions developed in his immediate historical environment. Then, I propose (...) to draw a parallel between Lakatos’s notion of “negative heuristics” and the high level of generalization Spinoza demonstrates in his propositions on the human body. This parallel allows me to show how Spinoza’s critical remarks on our knowledge of human body have heuristic value. (shrink)