Motion is only metaphysical if you try to shoehorn it in that. Motion is easily dealt with empirically and can be well described by partial differential equations or geometry.
Of course, it can be dealt with by PDEs. I am not discarding that approach. My point being that philosophical reflection can be supplementary to scientific reasoning. Metaphysics isn't an escape to a fantasy-world (as one mostly presumes) or is only dealing with ethics/God/free-will. It can and must understand the basic presuppositions of science -- something it cannot do itself -- as well as the basic structure of beings (ontology). It will have absolutely NO impact on scientific results, but it does adress the foundations of them, something a PDE cannot.
p.s. Motion makes very little sense anyway... already in the easy case of mechanical motion where an object is
BEING-in-place-A and moves to place-B (=
NOT-BEING-in-place-A). So, if it is truely
ONE-and-the-
SAME object... how can it at the same time BE and not-BE.
The question of Being, the meaning of Being (!= the question of the meaning of a human life) is quite foreign to science and is typically philosophical (i.e. ontological). What is Being? Every-thing "is." But what is "isness." How can things be?
Causality is not a "thing" it's a mathematical/phenomenalogical abstraction. But that doesn't make it metaphysical anymore than money or school grades are metaphysical.
I know. I was applying the Socratic method... So, what makes the abstraction of causality "appliceable" to the phenomenal world? Why is it not an empty concept like "the concept of God," "the concept of a first cause," or "the concept of a unicorn" (if you prefer) which our mind can freely construct but doesn't necessarily need to have any basis in that thing called reality. This is basicly Kants transcendental deduction; cf.
http://plato.stanford.edu/entries/kant-transcendental/#TraDed
I remember in class my prof showing us that we see everything in frames, like a video is 24 frames per second and that we figure out time from this but time itself, isn't 'real', just something we also impose on the world to get a better understanding of it. This is not my view in particular but Kant's, but i agree, just can't remember half of it now so will have to reread it later.
Well, it's not so much "impose on reality." It's the way our intuitions (sensations, if that term is more easy) are ordered. The event of a swan flying up is composed of "different events" (viz. it being on the ground, half-way, and in the sky,...). These different sensations not randomly connected but they have a certain order. Moreover, these sensations (stage-1,stage-2,...stage-n) have no principle to order themselves or connect themselves. Time, or better: temporality, for Kant is the way we structure/arrange our sensation (before, after, etc.).