Outlined Version of the Prime Mover Argument

My articles on the Prime Mover Argument for the existence of God (here, here, and here), also known as Aquinas’s First Way, are a bit lengthy and technical. This is needed for a full understanding/appreciation of the argument. However, it can take some time to really get through them. As such, I thought it might be useful to post a condensed, outlined version of the argument, in the form of a syllogism:

  1. Our senses observe that motion really exists
  2. Motion is a potency reduced to act
  3. Potency can only be reduced to act by another which is itself already in act
  4. Essentially ordered series of such motion must either terminate in a prime mover (which is Pure Act), or else have a circular or an infinite regress
  5. Essentially ordered causal series of such motion cannot in principle have a circular or an infinite regression
  6. Therefore, there must exist a prime mover, which is a being of Pure Act

Now, what can we know about this being of Pure Act?

  1. A being of Pure Act is, by definition, purely actual, with absolutely no potencies
  2. Anything that changes has potencies
  3. Therefore, the being of Pure Act cannot change (is immutable)
  4. In order to distinguish objects from other objects, they must have potencies
  5. Two or more beings of Pure Act would have no potencies, and thus would be indistinguishable, and thus identical
  6. Thus we can say that there is only one being of Pure Act (is one)
  7. All material objects have potencies
  8. Therefore, the being of Pure Act cannot be material (is immaterial)
  9. To come into or go out of existence is to change
  10. Therefore, the being of Pure Act can never have come into, and can never go out of, existence (is eternal)
  11. Every being which exists within time has potencies
  12. Therefore, the being of Pure Act cannot exist within time (is timeless)

So far we have established one being of Pure Act which is immutable, immaterial, and timeless. This already takes us to a conception of God. What more can be said?

  1. The being of Pure Act ultimately actualizes all potencies, so it is the ultimate cause of everything
  2. Thus it can be said to be “all powerful” (is omnipotent)
  3. The being of Pure Act is immaterial (see pt. 7-8 above)
  4. It is possible that all immaterial beings can be said to be personal beings (for a defense/explanation of this, see part 3 of my Prime Mover series)
  5. Furthermore, all causes must contain their effects either eminently or formally
  6. The being of Pure Act is the ultimate cause of all human attributes
  7. Therefore, the being of Pure Act must contain human attributes either eminently or formally
  8. Many human attributes are material in nature
  9. The being of Pure Act is immaterial
  10. Therefore, the being of Pure Act can only be said to contain these physical/material attributes eminently
  11. Some human attributes, such as personhood and moral nature, are immaterial
  12. Thus the being of Pure Act could be said to contain these attributes formally
  13. Therefore, we can say that the being of Pure Act contains personhood and a moral nature (albeit analogically)

Thus we have arrived at a being which is one, Pure Act, immutable, immaterial, timeless, eternal, omnipotent, and personal; and this being we call God.

To see the argument fully fleshed out, with each of the premises defended and key objections responded to, see the articles linked to above.

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