Newton's third law, causality, contemporaneity and Hume

Newton's third law (that every action has an equal and opposite reaction), seems to me to describe two aspects of the same whole, for the action and reaction occur during at the same time. Our ability to note how two things are contemporaneously interrelated via this third law totally belies Hume's crude conception of antecedent/consequent events as the only knowledge we can have of causality. (On the other hand, a Humean can object that this law is an example of superimposing a mathematical conception of objects [which involves a kind of simultaneity] onto the data of experience.)

If they are simultaneous, however, then why do we call one the "action" and the other the "reaction"? Such language misleads us into imagining that one occurs before the other. The answer might be that in our experience, one of the two things exerting equal and opposite forces usually seems to initiate the process: e.g., when I run on a track, I initiate this process, even though the earth exerts an equal and opposite force equal to the force I exercise upon the earth. This initiative is quite real; nevertheless is is unrecognized by one who merely notes the equivalence of opposed forces.

In spite of the Hume-friendly language used by Newton, the case of a contemporaneous action/reaction is more similar to Aristotle's per se cause than it is to Hume's antecedent and consequent. For the per se cause...