Just War Theory

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Just Ad Bellum- lawful authority & Just cause

Just Ad Bellum- lawful authority

  • War can only be declared by a lawful authority
  • Argued today lawful authority is a much more difficult to interpret
  • The concept of lawful authority also protects citizens from uprising

Just Cause- 1st developed by Aquinas

  • War should only be waged for a just reason
  • A nation has the right to protect its citizens if they are attacked or molested by another state
  • In order to correct a violation of rights
  • Grotius says a nation has the right to interfere in the affairs of a neighbour in order to prevent injustice from happening

Criticsm- Virtually everything could be made a just cause. These wide ranging reasons would lead to warfare emergence

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Ad Bellum- Right Intention & Last resort

Right Intention

  • Must strive for good and avoid evil
  • This fits in with Aquinas' philosophy and creates a teleological basis like knowing what your aims are
  • Aquinas uses the concept of peace when talking about right intentions
  • Whatever is done in what must ensure peace and harmony afterwards

Criticsm- War can actually create disharmony for the country that has been invaded

Voltaire- regarded war as totally irrational

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Ad Bellum- Last Resort & Likelyhood of success

Last Resort

  • Grotius said war must be a last resort
  • Lists methods countries should take in order to prevent war
  • Today UN is the intl. broker of disputes. They use security council- economic & domestics, & NATO for breaking disputes early on

Criticsm- can not effectively apply as most wars today are between rogue states.

  • The elemet of suprise is crucial in modern warfare as well

Likeyhood of sucess

  • Grotius asserts the likelyhood of sucess must be taken into account before war
  • Can you know what the results will be like?
  • The odds of sucess are not science- especially in an age of insurgency e.g. rebels in revlot
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Jus in Bello- Proportionality


  • The wars should be proportional to the reasons/damage caused
  • Wars should not be fought becuase of national honour
  • If we remove the idea of national honour, patriotic principle recognises the worth of the common link of humanity


  • The nature of modern warfare is contray to proportionality
  • Soldiers rely on logistics, communication, transport and provision
  • The fact war can attack infarastrucutre means war is dissproportionate but can be won quicky
  • It has the moral advantage of ending war quickly
  • It can be argued that saving lives at the cost of proportionality is better
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In Bello- Civillians in war & Weaponery

Civillians in war- Aquinas is clear civillians and innocent parties in war should not be targeted

  • Abused (later writers added)
  • Civillians are not to be used as a human shield
  • Grotius says civillians should not be held accountable for what their rulers do
  • Adds people should not suffer from the mistakes of their rulers
  • Violence should be shown to agressors and not those caught up in conflict
  • Collateral damange- The unintentional destruction of innocent people and their party
  • Civillians are not to be directly targeted. Torture must not be used and those captured in battle are to be returned to their families


  • Developed by Aristotle and Aquinas and it is largely asssumed that wars take place on the battle field
  • It became a clear code of ethics was needed to instruct Christians on ho to limit destruction
  • The development of new technology often forces a reciprocal on how to limit destruction
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Just Post Bellum

Considered as important before and after conflict

Many ethicsts argue war can only be moral if

  • it's result has been carefully considered
  • It's result is proportional to the reasons of war in the first place
  • The result can be ultimately succesful

The importance of sucess plays an important part in modern just war theory

Aquinas hardly mentions the Just Post Bellum situation but 'winning the peace' is a modern central issue


  • Just was theoy has been rejected on the grounds of the issues that come with post bellum. E.g. intl.relations and history

Brian Orend applies Grotius' principle and says that the Just Wat theory is the human rights of war

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Strengths and Weaknesses


  • Tries to protect innocet victims of warfare
  • Encourages combatants to think about hte moral implications of actions
  • Tries to prevent excess of warfare by the notion or retribution
  • Cultural traditions and laws of defeated nation are respected


  • Question of discrimination between a soldier and a combatant is central to just in Bello
  • The later 20th century has seen it as increasingly difficult to diffrentiate between who is guily and who is innocent
  • In certain countries, men and women are meant to do yearly military service as an obligation. Does this mean they are military figthers when they are home watching TV with  their children?
  • We can never achieve justice and equality
  • Just war theory is open to major abuses- it can be seen as a way people can justify wars no matter what
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  • Belief that under no circumstances is war okay
  • They believe in Christs teaching of turning the other cheek
  • Christian pacifists argue it is never okay to fight even if attaked

Pacifist virtue ethics- Violence demonstrates the individual therefore violene always harms moral agents.

  • This Christian view did not last. When Christianity became the official faith of the Roman Empire, Christians were called to fight under the banner of Jesus

Quakers see look to the peace testimony to bring peace to civil society.

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Christian approach

Because of the varied time span of the writing of the Bible there is no single viewpoint to war and peace. The Bible has two sides.

The Old Testament- shows a God of wrath and revenge bringing the destruction to the enemy of his people

  • Later Old Testament- shows a God of peace
  • New Test- written some decades after Jesus died

Sermon on the Mt

  • 'Blessed are the peacemakers'
  • Matthew- turn the other cheek

Johns Gospel

  • Christian duty to act in the same way God did- pacifist nature

Martyrdom Complex- Not resist violence but accept fate. Different biblical traditions show different christian approaches. Jesus says accept war as a last resort.  

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If war produces more happiness or pleasure than unhappiness, then  the principle of utility allows war.

  • It depends on whether the loss of life, the number injured or killed outweigh the benifit.
  • Utilitarians are difficult on the concept of war, it is probably best to say war should be the last resort.
  • Preference- prefrence or all those should count first
  • Appose war if the loss of human life looks too great


  • It is difficult to find a maxim which approves of universal killing as it is a contradiction on the law and will of nature
  • Treat all as an ends not a means
  • Act towards a kingdom of ends
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