In part 1 of this series, I explained what I mean by metaphysical demonstrations that lead to the God of classical theism. In part 2, I summarized an Aristotelian argument and defended the first two premises. Here, I defend the next step of the argument, which eventually leads us to a first mover who is pure actuality.

Some might protest that we are moving too slowly through the argument. But remember, patience is a virtue! In fact, even one atheist says Feser’s arguments are better than others because he carefully unpacks and develops them.

This atheist generously awards Feser’s book the designation of “Not a Steaming Pile of Crap” which Feser takes as great compliment.

Now, let’s dive back into the argument.

The Argument Outline

Recall that I summarized the argument as follows:

1. Change occurs.
2. This entails a distinction of actuality and potentiality.
3. Change requires a changer, and more generally, actualization requires an actualizer.
4. The existence of things here and now requires a hierarchically ordered causal chain of actualized potentials.
5. Hierarchically ordered causal chains of actuality and potentiality cannot go on indefinitely but must terminate in a first member, who is pure actuality.
6. There exists a first mover (the first member of the chain) that is pure actuality.
7. The first mover, existing as pure actuality, possesses the divine attributes.
8. The first mover is God.
9. Therefore, God exists.

In this post, I explain and defend premise (3) above.

Premise 3

Change requires a changer, and more generally, actualization requires an actualizer. This comports with common sense. Recall the example of the shoe horn on my desk. It is actually plastic and warped a certain way. It is potentially broken or melted plastic as well as potentially bent more than it is now. These potentialities are ways it can be or inherent capacities.

Whatever is merely potential cannot cause anything to change. The capacity to be melted plastic cannot cause the shoe horn to become melted plastic. Rather, a source of actual heat must be applied. The change from plastic to melted plastic requires a changer of some sort.

This reasoning holds generally. No inherent capacity can bring itself about, but rather requires something actual to bring it about. That’s what premise 3 says: change requires a changer, and more generally, actualization requires an actualizer.

Can Things Actualize Themselves?

If this premise is false, that commits one to the view that potentials can actualize themselves. That inherent capacities can cause themselves to be actualized, which is absurd. To see why, we examine another example.

Consider the idea of raising your arm above your head. Some might argue that your arm raised itself, so some things can actualize their own potentials. That analysis errs.

When you raise your arm, you cause the action, not the arm itself. In your mind, you form the intention to raise your arm, and the darn thing goes up. So, your willful choice (which involves the mind, brain, nervous system, and so forth) actualizes the movement of your arm.  So, this is the case of one part of a single organism actualizing another part’s potential, but not a case of a potential actualizing itself.

Feser deals with even more objections to this premise (i.e. the principle of causality) in Five Proofs of the Existence of God and Scholastic Metaphysics: A Contemporary Introduction. Suffice it to say that premise 3, which says actualization requires an actualizer, is secure. It follows from reason and comports with common sense. The common objections hurled its way all fail.

Next time, we turn to premises 4 and 5 in this argument for the God of classical theism.