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Essay on Just War Theory
YISS, G7 Summer Writing Program

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In Summa Theologiae: War and Justice (1485), Thomas Aquinas discusses when war is justified. He delineates three requirements for a war to be just. Next, Aquinas provides justifications for when one is allowed to use self-defense and to what extent. Aquinas's rules can be applied to modern-day warfare, such as the case of the Russian-Ukrainian war.  

War and Justice

There are two pillars in Aquinas's thinking: Jus Ad Bellum, which is the justification of war, or, in order words, the conditions needed for a war to be waged. There is also Jus in Bello, which is how the war is conducted. Aquinas first discusses Jus Ad Bellum by providing three requirements that must be fulfilled for a war to be just.
 
The first requirement is that a competent person of authority must declare war. Aquinas claims that the person who declares war must be someone in power, such as a ruler, but never a civilian or private person. This is because "it is not appropriate for a private person to declare war, since he is able to pursue his rights by recourse to the judgment of someone in higher rank." Aquinas also states that the job of civilians and ordinary people is to maintain peace within themselves, while the responsibility of declaring war should exclusively be done by the ruler. 

The second requirement is that there must be a just cause for the war. The people being attacked must deserve to be attacked, such as committing misconduct. Wars can have a just cause if they either "avenge wrongdoing" or a nation has "to be punished for failing to restore something that has been unjustly seized." However, if there is no reasonable cause behind an attack, the war is unlawful and wrong.

The last requirement is that the "intention of those making war must be good." In other words, the attacker must try to "promote some good or avoid some evil." They should not declare war to hurt or cause harm to others. War should also not be declared for the purpose of achieving domination or conquering other nations. The war cannot be just if the attacker has any of these traits.

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One point that is very crucial to consider is that every one of the three requirements must be fulfilled. For example, a war that was declared by a figure of legitimate authority to fulfill good intentions cannot be considered as a just war. Without a just cause, one cannot rightfully wage war. These three conditions are called necessary conditions, which means that if a war has only met less than three conditions  the war cannot be justified. The opposite of a necessary condition is a sufficient condition, which means if one meets a single condition, that alone can satisfy the conclusion. However, in Aquinas's reasoning, the attacker cannot lack any of the three conditions when waging war; therefore, they are necessary conditions.

 

Next, Aquinas explains what Jus in Bello is by arguing that killing a human in self-defense is permissible. He first defines the doctrine of double effect. That is, "One and the same act can have two effects, only one of which is intended, while the other is outside the intention." Aquinas says that all moral acts should be "categorized in accordance with what is intended, not what happens outside the intention." When the doctrine of double effect is applied to the ethics of self-defense, it translates to "the act of saving one's life and killing the aggressor." Even though it has double effects, Aquinas says self-defense can be justified as the desire to preserve one's life is natural and acceptable.

 

However, Aquinas imposes a limit to self-defense: "An act can become impermissible if it is out of proportion to the end at which it aims." This is called the principle of proportionality. That is, one must only use moderate force proportional to the damages that one has received in self-defense. Aquinas believes that self-defense loses its innocence if the force used in self-defense is greater than that of the attacker. 


Aquinas also says that one must have the right intentions for self-defense. There cannot be any private animosities or hatred toward the attacker that could encourage the victim to use more force than necessary. In addition, the one attacked must not intend to kill another in self-defense. Self-defense is justified and rightful if one does not have any of these desires.

Russia and Ukraine

We can use Aquinas's reasoning to determine whether Russia's attack against Ukraine is justified. First, we should consider Jus Ad Bellum and its three requirements. The first requirement is fulfilled as a person in authority declared war: Putin, who is the president of Russia. Next, we must analyze Putin's justifications for waging war on Ukraine. 

 

One justification that Putin gives is that NATO’s expansion threatens Russia's overall security. Putin is worried that the West will try to overthrow Russia. However, the issue with this justification is that NATO is not actively trying to enlarge itself--it is the countries that are trying to join NATO. In addition, research indicates that many countries looking to join NATO are minor nations seeking support and protection, as they are more vulnerable to attack. Moreover, NATO has not expressed any desire to take over Russia. Therefore, it is unreasonable for Putin to justify his war because of NATO expansion. 


Another defense that Putin uses in order to justify the war in Ukraine is the claim that Ukraine is committing genocide against ethnic Russians. Genocide is the destruction and killing of an entire race, ethnic group, or nation. Putin claims that in Donbas, a region of Ukraine, people "have been facing humiliation and genocide perpetrated by the Kyiv regime." However, these claims are baseless and do not have any concrete proof or evidence.

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Moreover, Putin's intentions are not pure. There are many claims that he wants to recreate the Soviet Union and that he is a megalomaniac. There is evidence to suggest that his main goal is to place Ukraine under the Russian umbrella. For example, there was a similar case when Russia attacked Crimea. Crimea did not provoke Russia in any way; Russia, on the other hand, wanted greater mobility to deploy its troops through the Black Sea. The annexation of Crimea is similar to the current Russian-Ukrainian war. Putin does not desire to create peace; instead, when looking at the effects of the war, we can see destruction and chaos. 

 

Lastly, we should consider Putin's conduct of war to determine if his war is genuinely just or not. According to Putin, his declaration of war was for self-defense against NATO, which he expected would eventually try to overthrow his nation.

 

However, in this case, the principle of proportionality shows that Russia is acting unjustly. NATO did not disclose any solid, concrete claims that it would attack Russia or surround the nation's area with NATO members. Russia, on the other hand, attacked not only the Ukraine military but also Ukrainian civilians. There have been countless cases of Putin's troops attacking residential areas and schools. According to the Geneva Conventions, this is a war crime. Putin claims that the buildings were used as military bases, yet the force Putin has used is severely out of proportion to his justification to attack in self-defense.

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