First Way, Part III: The Big Kahuna

P revious episodes in this exciting series, now drawing toward its thrilling climax:

Background lays out the history of the Argument from Motion and the impatience of those who demand that it prove more than it asserts to prove (e.g., that it prove that Jesus is Lord or some such thing, as if the objector were genuinely concerned about this shortfall). The initial proposition in Euclid does not prove every conclusion in Euclid, and the same is true in other sciences as well.
Part I A Moving Tale discusses the concept of "motion" used in the Argument from Motion, and how this is persistently misunderstood today. Kinesis means the actualization of a potential, so "change" is a better summation of the concept than the modern term "motion," which to the our ears sounds like local motion only.

Recall that we are using "motion," "change," "actualization [of a potential]," and "kinesis" as synonyms.

Part II Two Lemmas demonstrate that

Whatever is being actualized right now is being actualized by another. In many cases, a thing is changing as a whole because it is being changed by one of its parts. The cat crosses the room to the milk dish because its legs are moving it; its legs are being moved by its muscles, etc. This is because the changer must be actual while the changee must be in potency and what is in potency cannot make something else actual.
There cannot be an infinite regress of instrumental changers, since an instrumental actualizer has no power to actualize diddly squat unless it is concurrently being actualized itself. Obvious instrumental changers include... well, instruments: golf clubs, clarinets, et al., which have no power to strike balls, make music, etc. unless they are concurrently being employed by a golfer or musician. Not all instruments are obvious: e.g., the muscles are used instrumentally by the nerves to move the arms. But not all changers are instrumental, either, and such "accidental" series can in principle (if not in fact) regress without limit.

A number of objections and misunderstandings were also dealt with in these prior posts.

We are now ready for the Big Kahuna:
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