Reformulating the argument from change

Since roughly half the people I talk to about the argument from change don't understand the argument against an infinite regress of sustaining causes of change (and that's on me for not explaining it clearly enough), I've decided to offer an additional argument:

1. Changing things exist. (Premise)

2. Everything that changes exhibits actuality and potentiality. (Premise)

3. No potentiality can actualize itself. (Premise)

4. The regress of potentialities being actualized itself exhibits potentiality. (Premise)

5. Therefore, Pure Actuality exists. (Implied by 1 - 4)

Since I've recently written on the first three premises, I want to focus on (4).  What I like about this formulation is that it doesn't matter if the regress is finite or infinite.  Even if the regress of sustaining causes of change were infinite, it would still exhibit potentiality, since every member of the regress exhibits potentiality.

Like many cosmological arguments, premise (4) might be charged with committing a composition fallacy.  However, since there are many instances in which the whole is like its parts, we need to be careful.  It seems quite reasonable that the regress, finite or infinite, need not be actualized.  In other words, it's not a necessity that any member of the regress, or the regress as a whole should be actualized.  This implies that the regress as a whole must exhibit potentiality.

Now, since the regress exhibits potentiality, and no potentiality can actualize itself, it follows that the regress of potentialities being actualized can only be actualized by something external to the regress of entities that exhibit potentiality.  That's why Pure Actuality must exist, whether the regress of sustaining causes of change is finite or infinite.

Another nice feature of this version of the argument is that it's immune to the fairly common "quantum mechanics objection."  Although I don't find that objection sound, we can do a complete end-run around this issue, since the regress of potentialities being actualized also includes things that change on the macro level.