The just war theory is a Christian doctrine that provides criteria for evaluating whether it is morally justified to go to war. The just war theory has its roots in Biblical teachings and philosophies from Christian thinkers such as Augustine of Hippo and Thomas Aquinas. At its core, the just war theory aims to provide moral guidance on when war is permissible and how war should be conducted justly. There are two key components of the just war theory – jus ad bellum and jus in bello.
Jus ad Bellum – Justice of Going to War
Jus ad bellum provides principles to evaluate if going to war is morally justified in the first place. There are several commonly accepted criteria that need to be met to satisfy jus ad bellum:
- Just Cause – There must be a just and righteous reason to go to war, such as defending against an aggressor or protecting innocent lives.
- Legitimate Authority – War must be declared by a lawful government authority according to the nation’s laws and processes.
- Right Intention – The intent should be to pursue peace and justice rather than self-interest or revenge.
- Last Resort – All plausible alternatives to resolving the conflict must be seriously considered before resorting to war.
- Probability of Success – There should be a reasonable chance of success in achieving the war’s aims.
- Proportionality – The anticipated good outcomes must outweigh the expected harms caused by waging war.
If these jus ad bellum principles are not sufficiently met, then going to war is considered morally impermissible. However, satisfying these principles alone is not enough to make the decision to go to war just – the conduct during war must also be just.
Jus in Bello – Justice in War
Jus in bello provides ethical criteria on how war should be waged justly. Soldiers and leaders must act morally and minimize harms during warfare. The main principles of jus in bello include:
- Discrimination – Armed forces must distinguish between combatants and civilians, only targeting combatants.
- Proportionality – Any military action must be proportional to the desired legitimate military objective.
- Military Necessity – Armed forces should only use those measures needed to achieve justified objectives.
Following these jus in bello principles aims to protect non-combatants and limit unnecessary violence during warfare. Actions violating these principles, such as intentionally targeting civilians or using disproportionate force, are considered war crimes.
Key Figures in Developing Just War Theory
The just war theory traces back to Biblical teachings but was also greatly developed by prominent Christian thinkers.
Augustine of Hippo
Augustine of Hippo (354-430 AD) is considered one of the early founders of just war theory in Western civilization. Augustine emphasized that war could only be waged for righteous reasons, including defending the innocent and restoring peace. He argued that moral intentions, rather than self-interest, were imperative for war to be just. Augustine believed war should only be undertaken reluctantly as a last resort after all options for peace have been exhausted.
Thomas Aquinas
Thomas Aquinas (1225–1274 AD) expanded on Augustine’s ideas and developed criteria for the justification of war, including having a just cause, being declared by a lawful authority, and having the right intentions. Aquinas argued that three conditions had to be met for a war to be just: First, the war had to be declared and waged by legitimate authority. Second, those waging war must have a just cause, such as protecting innocents or correcting wrongdoing. Third, warring parties must have the right intentions focused on securing justice and peace rather than self-interest or vengeance.
Francisco de Vitoria
Francisco de Vitoria (1483-1546 AD) was a philosopher and theologian who further developed just war theory in the 16th century. He emphasized that war could only be justified against combatants, not innocents. De Vitoria also formulated early international law concepts, arguing that all nations and peoples had rights derived from the law of nations, which applied universally. This helped lay ethical restrictions around when war was permissible even beyond one’s borders.
Hugo Grotius
Hugo Grotius (1583-1645 AD) was an influential Dutch jurist who made major contributions to international law and just war theory. Grotius emphasized that war could only be justly undertaken as a last resort, when necessary to punish those who have committed unjust actions. He also developed criteria for how wars should be conducted justly, helping establish key principles of modern military ethics.
Emmerich de Vattel
Emmerich de Vattel (1714-1767 AD) was a Swiss philosopher and legal expert who further refined modern just war theory in international law. Vattel argued that war could only be waged for defense against aggression or to punish a nation that refused to make amends for wrongs committed. He also asserted that wars should be fought through regular forces using lawful combat methods, respecting the rights of civilians and enemy soldiers. Vattel’s writings were highly influential in 18th century international law and diplomacy.
Key Biblical Principles
While just war theory developed significantly under major Christian thinkers, its foundations lie in several key Biblical principles:
- The inherent dignity and value of human life (Genesis 1:26-27)
- The avoidance of unnecessary violence (Exodus 20:13)
- Seeking just and righteous purposes above self-interest (Psalm 4:5)
- Striving earnestly for peace (Matthew 5:9)
- Responsibility to protect the vulnerable and oppressed (Proverbs 31:8-9)
- Acting with love even toward enemies (Matthew 5:43-48)
These Biblical values and teachings helped shape just war theory doctrine over the centuries.
Historical Application and Evolution
While early Christian thinkers established the doctrine of just war theory, its tenets continued developing and were clarified in their application throughout history.
Medieval Crusades
During the medieval Crusades beginning in the 11th century AD, just war theory was often invoked to justify military campaigns waged by European Christian nations against Muslim powers. However, later examination found many of the Crusades failed to meet just war criteria.
Spanish Scholastics
In 16th and 17th century Spain, theologians and philosophers known as the Spanish Scholastics such as de Vitoria examined just war theory in the context of Spanish colonization in the Americas. This contributed to refined principles around war between nations.
World War II
In the 20th century, the rise of modern warfare technology and totalitarian regimes confronted existing just war doctrine. The Allied war efforts against the aggression of Nazi Germany and Imperial Japan tested thinkers on the applicability of just war principles.
United Nations Charter
Following the immense destruction of World War II, international law enshrined in the 1945 United Nations Charter aimed to restrict the unilateral ability for nations to wage war, emphasizing collective action, peaceful resolution, and self-defense against aggression.
Modern Era
In recent decades, just war theory continues developing, grappling with newer warfare technology, rise of non-state actors, threat of terrorism, humanitarian interventions, preemptive strikes, and nuclear deterrence. Ethicists continue examining the doctrine’s moral applicability to 21st century conflicts and international relations.
Criticisms of Just War Theory
While just war theory aims to provide a moral framework on war, it has faced some criticism:
- Its criteria can be interpreted subjectively and inconsistently to rationalize warfare.
- Changing technology and types of conflict challenge traditional principles.
- Wars rarely meet perfect just war standards, yet doctrine may still justify imperfect warfare.
- Just war theory is sometimes viewed as contradictory or futile in achieving peace.
Advocates argue just war doctrine still provides an important moral guidepost and can evolve with new context. But debate persists around its limitations in consistently preventing unjust wars.
Christian Pacifism
Christian pacifism offers a contrasting view to just war theory. Pacifism rejects war altogether based on Biblical teachings to love one’s enemies, pursue nonviolence, and turn the other cheek when faced with aggression (Matthew 5:38-48). Early Christian pacifists cited Jesus’ Sermon on the Mount.
Historic peace churches adopting Christian pacifism include Quakers, Amish, Mennonites, and Brethren. They argue that nonviolence and peaceful resolution accord better with Biblical values than ethical criteria that may still permit wars. Pacifists believe just war theory offers paradoxical moral compromises rather than principled nonviolence.
Conclusions
In summary, just war theory represents a long-standing Christian moral doctrine that aims to provide ethical guidance on going to war and how war should be conducted justly. Its foundations lie in Biblical teachings and Christian thinkers from Augustine to Aquinas formulated key just war principles still influential today. Over the centuries, just war criteria have developed and been clarified in their application. The theory continues evolving, grappling with moral questions around modern warfare. Christian pacifism offers a contrasting view rejecting war altogether. Debates around the tenets and limitations of just war theory persist in Christian ethics and its ability to prevent unjust wars.