Inertia

Had a brief discussion about physics and science with a "professional" phyisicist yesterday on Facebook; I had to dust off the cobwebs in the attic of my mind. I was thinking about inertia (especially as formulated by Newton). How would one go about questioning or even refuting it as a postulate or axiom? By looking at the explanation of change? Does anything non-living move itself? And should we not take into consideration natural versus violent motion?

If simple bodies do not move themselves but are moved by another... and if it is the First Mover that moves them when the motion is natural, then the end or purpose of that motion is determined by the First Mover as a part of their nature.

It may be natural for some things to persist in changing place (locomotion) until they come to rest for some reason. But is it possible for other things to be in perpetual motion for a reason that we cannot readily discern? The end of motion is not rest but some perfection extrinsic to the thing? (example: the celestial bodies? - motion in a 'circular' path) At the moment I cannot think of a reason to rule out this possibility outright.

On the other hand, I do not have any a priori reason yet to claim either that all instances of natural locomotion must be of the second kind either. (As the principle of inertia would seem to entail.)

[Various forms of 'rectilinear' motion are due to attractions proper to the natures of certain things? Are there any exceptions?]

One who has been instructed in modern physics will assume inertia is an uncontroversial or evident truth, on par with the fact of the earth being round. How would awaken him from such a dogmatic slumber? (He did subscribe to a form of scientism, saying that the only valid knowledge of physical reality was obtained through the scientific method. And he claimed that teleology was pseudoscience.)