Week 26 – Thomas Aquinas, just-war theory

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 argued that things change, because they have a potentiality to change. For example, if you want to heat your dinner, you put it in the microwave. But the microwave is only able to heat your meal because the meal had a potentiality of becoming hot and the microwave had a potentiality of heating it. Once this occurs, your meal is now actualized and heated. Thomas Aquinas built upon this concept and tried to find the “Unmoved Mover”. Aquinas describes motion as going from a potential state to an actual state (same as Aristotle). He also says that no potential can actualize itself, it must be made actual by something outside itself. Example: a car is being pushed by the application of the hands and force of a person. But those hands are able to take their position thanks to the nervous system and so on. So who is the Unmoved Mover? Who is the first member of these actions? It must be someone who, unlike all of the other member of the series, does not have to be actualized by anything else; this being must be Pure Act (pure actuality) and it must have no potentiality. With no potency to realize, this being could not move nor change. And that is God.

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

God is immaterial

If he was material, he would have to be changeable – but a purely actual being cannot be changeable. If he was changeable, he would have to be potential. God also has to be outside time and space; being inside time and space likewise entails changeability (you can change from being at 2PM to 3PM).

God is all-powerful

Aristotelian’s principle: a cause cannot give what it does not have; thus the cause of a feature must possess that feature either formally or eminently. Formally = in the case of a lighted torch causing a stack of papers to light on fire; eminently = in the case of a cigarette lighter, which, while not itself on fire, has the ability to produce fire. Another good example is that something that doesn’t have heat cannot heat up your dinner. This means God must be all-powerful in order give us all the things we have.

Describe the main principles of just-war theory.

Just-war theory focuses on the issue of under which conditions can be a war considered legitimate. It was primarily a Christian invention. It included conditions like “The vassal doesn’t violate his feudal oath if he refuses to follow his lord into an unjust war”, “War is justified only by the injustice of an aggressor, and that injustice ought to be a source of grief to any good man, because it is human injustice”. Thomas Aquinas added three conditions that must be met in order for a war to be legitimate: the authority of the sovereign by whose command the war is to be waged; a just cause is required; it is necessary that the belligerents should have a rightful intention, so that they intend the advancement of good, or the avoidance of evil.

Today, all of the principles mentioned above stay the same, but it is also necessary to have a probability of success (e.g. don’t attack a country you know you won’t conquer) and non-combatants may not be targeted. (such as schools, hospitals, etc.)

Leave a Reply