Question:

I was thinking about Zeno's paradox of motion today and decided on an explanation that I'd like to check. As I've heard the paradox stated, one premise is that in order to get from A to B you have to first get to the midway point, call it C. Then there are other premises resulting in the conclusion that motion is impossible. But doesn't the above premise already allow for the possibility of motion, making you agree that motion to C is possible before going on to claim that motion to B is not?
Perhaps there is another way to state the paradox, then?
Thanks much.

Topics:

Space

Accepted:

April 29, 2007

Right, so it seems you think the argument is self-undermining. It assumes that you can get to the midpoint, C, and then it goes on to prove that motion from C to the endpoint B is impossible. Maybe we need to rethink our assumption that we could get to C! And indeed, other versions of this paradox of Zeno's work in that way. In order to get from A to B, this version runs, we need to get to the midpoint C. But in order to get from A to C, we need to

that interval'smidpoint, C1. And in order to get from A to C1, we need to get toitsmidpoint C2,ad infinitum.The strategy is always the same: to find a way of taking something finite (in this case, the racetrack) and dividing it into infinitely many parts; then arguing that a related task (here, running to the finish line) that looked to be finite really involves an actual infinite number of subtasks (here, reaching all the midpoints); and then concluding that, because one cannot complete an infinite number of tasks, the original task is impossible.

All these steps have captured the imagination -- of mathematicians, philosophers, poets. Blake wrote about the first: