Argument from Gradiation: Outline
The fourth way borrows heavily from the concept of the platonic forms, although it's important to note that Aquinas did not consider God to be a platonic form. Forms are essentially ideals. No dog in the universe may be a perfect example of what a dog is, but an ideal, or form, still exists. The same is true for circles, squares, and so on. Because the forms are perfect, they also have the most reality within them. Thus the universe can be conceived as an ascent from less real to more real, and Aquinas borrows from this rhetoric.
- We perceive that things differ in degrees
- When speaking of how things differ, we always compare it to its maximum
- Humans can be both good and bad
- Therefore, the maximum goodness does not exist within humans
- Therefore, perfection, or maximum good, must exist elsewhere
- We call this maximum good God
Argument from Gradiation: Explained
Aquinas presupposes that there are different levels of being within the universe. Humans have a greater amount of being compared to animals while angels and other divine entities surpass humans on their amount of being. The entity with the ultimate amount of being is God. Aquinas also supposes that the more being that resides within an entity, the greater the good within that entity. Thus if God is supreme being, he is also supreme good. The idea of a maximum is already presupposed in our ability to recoginize that different things exist at different degrees. We notice that warm objects differ from cold objects because we compare the heat of an object to a maximum amount of heat.
Objections
Argument from Polar Concepts
If Aquinas' fourth way can be used to determine that a supremely good being exists, then can we not conclude that a supremely evil entity exists? If there are to be degrees of evil, there must also be a maximum evil. If not, how can we conclude a maximum good from degrees of good? The problem with a supremely evil being is that such a being would be all-powerful and quite literally the anti-version of God. Satan is often considered to be the anti version of God, yet Satan isn't considered to be all-powerful.
Sources
Archie, Lee C, "Thomas Aquinas, 'The Argument From Gradiation,'" Philosophy of Religion, June 26, 2006.
Dawkins, Richard. The God Delusion. Black Swan, 2016.
Gracyk, Theodore. "St. Thomas Aquinas: The Existence of God Can Be Proved in Five Ways." Aquinas: Five Ways to Prove That God Exists -- The Arguments.