Thomas Aquinas was a catholic priest from Italy.
He was from the Dominican Order. His works are part of High Scholastic.
He was a proponent of natural theology (theology which is based on reason and experience).
He provided arguments on the nature of God, human virtues, etc.
His philosophical and technological ideas are based upon Aristotle's metaphysics and logic.
His best known work is Summa Theologiae.
Question 40 of Summa Theologiae is the question of just war.
Waging war is unlawful, both, by the will of God and by the fact that war is contrary to peace (virtue), therefore, war is contrary to virtue and therefore its a
Thomas Aquinas response to this argument: (just as Augustine points out) God and the bible may label war as a sin, but they do not forbid soldiering.
In other words, for Aquinas only unjust war is sinful and unlawful.
If war is waged the right way, then it is not a sin, and it is not to be considered unlawful.
What is the right way to wage war? And what was is not unlawful?
To answer this question. Aquinas formulates the first 3 conditions of jus ad bellum.
1. It must be waged by the proper authority.
2. Just war requires a just cause. Ex: there should be an identified aggressor in order for the was to be waged.
3. Just war requires rightful intention, such as peace. War shouldn't be waged unless it is for the avoidance of evil, and securing peace.
ALL THREE CONDITIONS MUST BE MET FOR A WAR TO BE CALLED JUST WAR.
Clerics and bishops should not participate in war. Why?
They are not prepared to fight and they can serve people better in counselling than it fighting.
Wars should be fought by professional soldiers.
Laying ambush is justified, since it is not a real deception / sin, but rather concealing information, intentions from the enemy.
Since the purpose of just was is securing peace, laying ambush is acceptable.
Same argument is made for fighting on holy day.
What did Aquinas barrow from St. Augustine?
Augustine elaborates on co