There is a longstanding definition of instantaneous velocity. It saysthat the velocity at t 0 of an object moving along a coordinate line is r if and only if the value of the first derivative of the object's position function at t 0 is r. The goal of this paper is to determine to what extent this definition successfully underpins a standard account of motion at an instant. Counterexamples proposed by Michael Tooley (1988) and also by John Bigelow and Robert (...) Pargetter (1990) are reinforced and illuminated by considering the presence or absence of changes to the object's motion. (shrink)

We argue that the view that we misperceive time as passing is self-undermining.

The arena of the philosophy of time has been largely concerned with deciding whether tense distinctions reflect absolute metaphysical distinctions or not. After bringing the debate over the metaphysical status of instantaneous velocity to bear on the debate over the nature of temporal passage, I argue that we should further investigate whether aspectual distinctions reflect objective and absolute metaphysical distinctions too. I conclude that those who think that being realist about tense uniquely makes room for the idea that time passes (...) should be realist about the progressive too. (shrink)

Nonphilosophers, if they think of philosophy at all, wonder why people work in metaphysics. After all, metaphysics, as Auden once said of poetry, makes nothing happen.1 Yet some very intelligent people are driven to spend their lives exploring metaphysical theses. Part of what motivates metaphysicians is the appeal of grizzly puzzles (like the paradox of the heap or the puzzle of the ship of Theseus). But the main reason to work in metaphysics, for me at least, is to understand the (...) shared world that we all encounter and interact with. And the shared world that we all encounter includes us self-conscious beings and our experience. The world that we inhabit is unavoidably a temporal world: the signing of the Declaration of Independence is later than the Lisbon earthquake; the Cold War is in the past; your death is in the future. There is no getting away from time. (shrink)

Zeno argued that since at any instant an arrow does not change its location, the arrow does not move at any time, and hence motion is impossible. I discuss the following three views that one could take in view of Zeno's argument:(i) the "at-at" theory, according to which there is no such thing as instantaneous velocity, while motion in the sense of the occupation of different locations at different times is possible,(ii) the "impetus" theory, according to which instantaneous velocities do (...) exist but these are only contingently and causally related to the temporal developments of positions,(iii) the "no instants" theory, according to which instants in time do not exist, and hence instantaneous velocities do not exist, while motion, in the sense of different areas occupied during different time intervals, is possible.I argue that, despite the fact that there have been interesting and relevant developments in mathematics and physics since the time of Zeno, each of these views still has serious drawbacks. (shrink)