Western Civilization I, Week 26 – Thomas Aquinas, Just-War Theory

(1) How does Thomas Aquinas, following Aristotle, argue for the existence of God on the basis of the concepts of potency and act (or potentiality and actuality)?

Aristotle’s potency and act refers to when something moves from the potential to be something to the actuality of being something. For example, if you have a pot of water, it has the potential to be boiling. Once you turn on the heat, it moves to actually being boiling. Based off of this concept, Aristotle came up with the Unmoved Mover, basically saying that there has to be some unmovable force that moves everything else in the universe. If you picked up a stick and poked a can with it, did the stick make the can move? No, it was your hand making the stick move that made the can move. But then what moved you? Aristotle argues that everything has the potential of motion, and the Unmoved Mover has to actualize that potential. Thomas Aquinas claims that the Unmoved Mover Aristotle speaks of is God.

(2) Choose two of the divine attributes discussed in lesson 127 and explain how Aquinas derives them.

    Aquinas says that one of the divine attributes of God is that He is pure actuality, meaning that He never just has the potential to be something, He is it. He is the one who actualizes potential of other things. Aquinas uses this argument to prove God’s oneness. He says that if there were multiple Gods, then neither would be pure actuality. If there were two co-kings of a kingdom, neither would be the highest power in that kingdom because the other can still veto their decisions and make choices for the kingdom, etc. If God is not the highest power, He would still have the potential to be the highest power, and that would mean that there would have to be some being above God who can actualize God’s potential. On another note, if there were multiple Gods, there would have to be a way to distinguish one from the other. This would have to mean that one lacks something the other has. If this is the case, said God has unrealized potential that needs to be actualized by a higher being. God also has to be immaterial, because if He were material, that would imply that there is some other being actualizing His potential since material things cannot actualize their own potentials.

(3) Describe the main principles of just-war theory.

Just-war theory talks about the right way to go about a war, and touches on three stages of warfare. Jus ad bellum, jus in bellum, and jus post bellum.
Jus ad bellum, meaning “justice before war” talks about appropriate reasons for going into a war. One justified reason to go to war is if another nation or state takes some of your land. In that case it is alright to take back the land that was stolen from you, but not more. War must also be declared by the proper authority. The ruler of a nation can declare war, but any individual or group cannot. Another good reason for war is in defense of the helpless/poor/weak, or in self-defense.

Jus in bellum refers to justice during a war, and explains that civilians, injured soldiers, captives, and people who surrendered should not be attacked, and prisoners of war should be treated fairly and not tortured. The just war theory states that harming the civilian population, such as by cutting off access to resources, exported and natural, should be moderate and only if absolutely necessary. The theory also writes off weapons and warfare strategies that cause mass destruction.

The next stage of war, jus post bellum, or justice after war, talks about how the reason for ending the war and the declaration of surrender should be proportionate to the reasons for going to war in the first place. For example, if the reason for starting the war was to gain back stolen land, then the surrender should be after the land is retaken.


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