Spinoza on the persistence of bodies

In my dissertation I examine and resolve a fundamental and previously unnoted tension between Spinoza’s metaphysics and his moral philosophy. Spinoza’s metaphysics, I argue, entails that bodies have temporal (as well as spatial) parts; his moral philosophy, however, requires that human bodies (and minds) lack temporal parts. In this dissertation I defend a charitable reconstruction of Spinoza’s theory of bodily persistence which resolves this tension. I begin the dissertation with two chapters concerning the nature of time. In the first chapter I argue that according to Spinoza all bodies (whether past, present, or future) are equally real. I argue that if God’s mind has adequate ideas of all present bodies (a claim all Spinoza scholars accept), then it must also have adequate ideas of all past and future bodies as well. But given Spinoza’s parallelism, if God’s mind has an adequate idea of a body, then it must exist. Thus, all bodies (whether past, present, or future) must exist in a Spinozistic universe. In the second chapter I argue that, in Spinoza, temporal passage (or the “moving now”) is an illusion arising in exactly the same way as the illusion of the closeness of the sun and the illusion of libertarian free will. Thus, Spinoza’s theory of time is not only eternalist, but also tenseless. The third chapter concerns the nature of bodies. In this chapter I argue against the widespread view that Spinoza offers two different theories of bodily essence in the Ethics (the “ratio of motion and rest” theory after 2p13s and the “striving [conatus] theory” at 3p7). This mistaken view arises from an ambiguity in the literature concerning exactly what kind of thing a conatus is supposed to be. Some scholars claim that a conatus is a tendency, others that it is a force, and still others that it is an activity. Many scholars are inconsistent on the issue. In this chapter I provide a new argument for the activity interpretation of conatus. Striving is something that bodies do. Furthermore, I argue that once this confusion is resolved it quickly follows that a “ratio of motion and rest” and a “conatus” are two ways of thinking about the same thing (namely, the essence of a body). I conclude that Spinoza offers only one theory of bodily essence in the Ethics. In the fourth chapter I reveal the basic tension within Spinoza’s system. If the essence of a body is a complex motion, then (given Spinoza’s Cartesian theory of motion) it follows that the essence of a body must be temporally extended. Moreover, given Spinoza’s theory of time, it follows that each temporal part of a body’s essence must also exist. Thus, it seems as though bodies must be temporally extended and have temporal parts. This conclusion is deeply problematic, however, because Spinoza’s moral and political philosophy presupposes a theory of human bodies (and minds) whereby they do not have temporal parts. Thus, Spinoza seems to be committed to a contradiction at the very heart of his system. In the fifth and final chapter I provide a charitable reconstruction of Spinoza’s views on the nature and persistence of bodies which reconciles his metaphysics with his moral philosophy. While this solution cannot be directly attributed to Spinoza, I argue that it follows naturally from his other commitments and is likely consistent with the rest of his system. In short, I argue that Spinoza has the resources within his own metaphysics to accept a kind of (what we would today call) “stage” or “exdurance” theory of persistence. According to this theory, persistence is not a matter of diachronic identity nor temporal parts. Instead a body persists by having “temporal counterparts” or “stages” at later and earlier moments. The key part of any such theory is explaining how a stage can be in some sense the same as earlier and later stages without being identical to them. Spinoza’s theory of formal and actual essence, I argue, provides a perfect basis for such a distinction. Spinoza, I conclude, can avoid the tension in his system without any significant costs by accepting a “stage theory” of persistence whereby each stage of a persisting body is a numerically distinct expression of one and the same formal essence. This suggestion provides the different stages of a persisting body enough similarity for diachronic sameness (and thus persistence) while avoiding diachronic identity (which would be inconsistent with his temporal parts metaphysic of bodies)