Philosophy Friday: Thomas Aquinas

Thomas Aquinas: 1225-1274

            Thomas Aquinas brought the dawn of a new age. Like Augustine, Aquinas valued the ancient philosophers. Aquinas’ goal was to present Christianity in a rational and logical way. He is most famous for his “Five Ways,” which are five arguments for the existence of God.

            Aquinas’s first way is an argument from motion. In this argument, Aquinas points to three accidental changes: changes of location, quality and quantity. Changes of location are as simple as a leaf falling from a tree or as complex as a ship sailing across the ocean. Changes of quality refer to changes such as a person growing old or climates heating and cooling. The changes of quantity refer to an increase or a decrease. Aquinas argued that everything that changes must have been changed by an unchanging being. Everything that moves must have been moved by an “unmoved mover” otherwise nothing would have ever been moved at all.[1] 

His second way is the argument from causation, which is closely associated with the first way. The argument of causation is focused on the efficient causes. The efficient cause is the agent that causes an effect. The efficient cause of a log burning is the flame. According to Aquinas, every effect we see must have had a cause, but that cause must also have had a cause. This cycle would go on for infinity if there was not a first cause, and there must be a first cause for any of the subsequent actions to have followed.[2]

The third way is the argument from possibility and necessity. If it is possible for some things to be made or corrupted, than it is possible for them to exist or not exist. If everything has the possibility of existing or not existing, everything at some point does not exist. If so, then nothing could have ever existed unless a necessary being brought it into existence.[3]

The fourth way is the argument from gradation. According Aquinas, everything that exists exists on a scale or a grade of perfection. There are things that are more good and things that are less good. There also exists things that are maximally good, true, and noble. If there is a maximally true thing, than it is a maximally true being, and it is the cause of everything else of lesser goodness. [4]

The fifth way is the argument from governance. This argument states that if something acts in such a way as to bring about the greatest result, one could also say it is attaining an end. Furthermore, if beings act in order to attain an end they are doing so under the direction of an unthinking being, namely, God. [5] 

            Thomas Aquinas’ arguments for the existence of God were influential for Christian philosophy. Aquinas was perhaps the first Christian apologist, but he was certainly not the last. Many philosophers would follow his example in defending the “reasonable” faith of Christianity.

---

[1].  Timothy J. Pawl, “Aquinas’ Five Ways,” Just the Arguments: 100 of the Most Important Arguments in Western Philosophy, ed. Michael Bruce and Steven Barbone (Chichester, West Sussex, U.K.: Wiley-Blackwell, 2011), 10-12.

 [2]. Ibid., 13-15.

[3]. Ibid., 14-15.

[4]. Ibid., 15-16.

[5]. Ibid., 16-17.