It's not really clear to me how we have resolved Zeno's
paradox, though it's clear that we have. I wonder whether we
have done that by modeling a continuum, a continuum of space,
of time, of speed, of what-have-you -- by using the reals,
which is to say a Dedekind-complete, totally-ordered field.
If that is the case, then Dan is right -- in a sense --
except that all the resolving was done in the re-modeling of
the situation that gives rise to the paradox, and ends
just before Dan begins his part of the problem.
I am reminded of a course in advanced calculus I took,
possibly the most difficult math course I've had. It
covered one theorem: the modern, generalized version of
Stokes' Theorem, and it took us an entire semester of hard
work to acquire the background we would need to prove it.
However, when it came time to prove Stokes itself, it was
just handed off as an exercise, plug-and-chug. The
hard-thinking part was woven into the machinery. I think
this may be similar.
I recently had a discussion with WM about the Intermediate
Value Theorem, and its equivalence to Dedekind completeness
in this case (something I'd just learned or re-learned). One
way (of many ways) to state the theorem, it seems to me, is
"Two continuous curves that cross meet at one or more points."
Isn't that the sort of property we want included in our
description of the continuum?
My conception of how we get from a properly described
continuum to the finessing of the infinite actions is
more than a little blurry for me.
(Speculating here:)
One of the many points that Virgil has made to WM is
that any real number interval, such as [0, 1], necessarily
contains uncountably many undefined reals, even if the
endpoints are always defined or referenced in some fashion.
I wonder if The Secret of Resolving Zeno's Paradox lies
in treating the unresolved, unreferenced greater mass
of points properly (and what is "proper"? Dedekind-
completeness, because crossing lines should meet).
Once we figure that out, all those infinite actions
or space-points or time-events sink back into the
anonymity of the unresolved, unreferenced greater
mass of points. And no more paradox.
The amusing thing about my speculation would be if the
problem of the infinite points to which Achilles had
to go to were resolved by introducing a larger infinity
of points to the problem.
I wonder -- if WM or David Petry somehow got their
way, hard as that is to imagine, would Zeno's Paradox
return from its grave to trouble us? Wouldn't that
be a fine howdy-do, given that they are always going
on (and on and on) about how Mathematics Should Model
Reality, if their "improvements" broke a pretty basic
capability of mathematics to do that very thing.