A question about rest and motion

✍ Scribed by Frank Jackson; Robert Pargetter

• Publisher: Springer Netherlands
• Year: 1988
• Tongue: English
• Weight: 305 KB
• Volume: 53
• Category: Article
• ISSN: 0031-8116
• DOI: 10.1007/bf00355681

✦ Synopsis

We should be able to come up with an intuitively satisfying answer to this question. The case is simple, logically possible, and for all we know physically realizable. ~ One might expect trouble with a question like, 'If X moves according to: s = t sin 1/t, is it moving or at rest at t = 0?', but not with our question. Nevertheless, a number of initially not unattractive possible answers turn out to face serious objections. We will argue this, and then present our own answer.

SIX WRONG ANSWERS (i) "Xis moving at t -----0, as s = t for t >t 0." But we might have specified X's position over time by: s = 0 for t ~ 0, s = t for t > 0. This specification and the original one are precisely equivalent. They put X in exactly the same positions at exactly the same times. Indeed, the case for saying that X is moving at t = 0 is precisely paralleled by saying that X is at rest at t = 0. How, then, can we non-arbitrarily plump for one hypothesis over the other? There is nothing to make the difference.