If a spinning sphere casts a shadow, does the shadow also spin? This riddle is the point of departure for an investigation into the nature of shadow movement. A general theory of motion will encompass all moving things, not just physical objects. Ultimately, I argue that round shadows do indeed spin. Shadows are followers of the objects that cast them. Parts of the shadow correspond to parts of the leader, so motion of the caster's parts accounts for motions of the (...) shadow's parts. I conclude with a discussion of how the dynamic aspects of shadows impose subtle constraints on other puzzles about shadows. (shrink)

Our topic is the ontology and persistence conditions of material objects. One widely held doctrine is that identity-over-time has causal commitments. Another is that identity-over-time is just identity as it relates one object that exists at two times. We believe that a tension exists between these two apparently sensible positions: very roughly, if identity is the primary conceptual component of identity-over-time and—as is plausible—identity is noncausal, then the conceptual origins of the causal commitments of identity-over-time become a mystery. We will (...) begin by formulating the two widely held doctrines and our puzzle more fully and more carefully. Then, the remainder of the paper will be devoted to analyzing views one might adopt that could minimize the tension. (shrink)

Our topic is the ontology and persistence conditions of material objects. One widely held doctrine is that identity-over-time has causal commitments. Another is that identity-over-time is just identity as it relates one object that exists at two times. We believe that a tension exists between these two apparently sensible positions: very roughly, if identity is the primary conceptual component of identity-over-time and—as is plausible—identity is noncausal, then the conceptual origins of the causal commitments of identity-over-time become a mystery. We will (...) begin by formulating the two widely held doctrines and our puzzle more fully and more carefully. Then, the remainder of the paper will be devoted to analyzing views one might adopt that could minimize the tension. (shrink)

Essentialism is widely regarded as a mistaken view of biological kinds, such as species. After recounting why (sections 2-3), we provide a brief survey of the chief responses to the “death of essentialism” in the philosophy of biology (section 4). We then develop one of these responses, the claim that biological kinds are homeostatic property clusters (sections 5-6) illustrating this view with several novel examples (section 7). Although this view was first expressed 20 years ago, and has received recent discussion (...) and critique, it remains underdeveloped and is often misrepresented by its critics (section 8). (shrink)