Skip to content
Skip to main content

About this free course

Download this course

Share this free course

The moral equality of combatants
The moral equality of combatants

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

1 Three components of the Just War Tradition

In this course we are going to be thinking about war, and the morality of war. To understand what philosophers have written in this area, we need to distinguish two things. The first is a tradition of thought, and the second an area of philosophical enquiry.

The first, known as ‘the Just War Tradition ’ is a long historical tradition which is difficult to summarise in a non-controversial manner. It is, more or less, the claim that there is a set of conditions which can act as a kind of checklist for whether a war is just or not. The Just War Tradition takes its form because it originated as a source of advice for princes and kings who were considering whether or not to wage war. In particular, the early modern just war theorists were advising Christian princes on whether their warfare was justified. They were advised that, if their actions met the conditions specified the Just War Tradition, then they were morally justified in waging war. One reason why the Just War Tradition is important today is that it has been encoded in the rules of war – the laws covering international conflict – at the Geneva Convention, the Hague Convention and so on. These conditions were conventionally divided into two groups, one concerned with when one may go to war and the other concerned with how one may fight. These two sets of conditions are standardly known by their Latin tags: Jus ad Bellum and Jus in Bello . The word ‘ jus’ refers to something like rightness, or justifiability, or justice; ‘ bellum’ and ‘ bello’ both mean war (the ending of the word changes in Latin, according to the role of the word in the sentence, just to make life difficult for schoolchildren); ‘ad ’ means ‘to’ or ‘towards’; and ‘in’ means ‘in’. ‘Jus’ is sometimes spelled with an ‘I’, but however it is spelled, the word is conventionally pronounced softly, with a ‘y’ sound at the start. For ease of reference I will shorten the Jus ad Bellum to JaB and the Jus in Bello to JiB . These conditions are summarised in the box below.

There are six conditions of Jus ad Bellum and two conditions of Jus in Bello . Here is the account given by a present-day just war theorist, Uwe Steinhoff.

The Jus ad Bellum ( JaB ) conditions:

  1. A legitimate authority (king, president, parliament and the like) decides on the entrance into war.
  2. One has a just cause for entering into war (for example, defence against an aggressor).
  3. One pursues the war with the right intention, namely for the purposes of a just cause (thus, for instance, one does not harbour the plan of not ceasing conflict once the aggressor has been thwarted or possibly even punished, and of getting further advantages for oneself, such as the increase of one’s own power or the acquisition of territories or resources).
  4. The war fulfils the condition of proportionality, that is, it is a proportionate means, which is to say that it does not create more mischief than it averts.
  5. The war also fulfils the condition of having prospects of success (in the sense of prospects of victory).
  6. The war is the last resort ( ultima ratio ), that is, there are no other promising alternatives available.

The Jus in Bello ( JiB ) conditions:

  1. The condition of proportionality must be fulfilled. That is, the violence used in the war must be proportional to the injury suffered. States are prohibited from using force not necessary to attain the limited objective of addressing the injury suffered. (One is not to bomb a country ‘into the Stone Age’ if victory may also be had less destructively.)
  2. The principle of non-combatant immunity must be observed, that is, some distinction must be made between combatants and non-combatants or, respectively, between legitimate and illegitimate human targets of a direct attack. That is, civilians are never permissible targets of war, and every effort must be taken to avoid killing them. The deaths of civilians are justified only if they are unavoidable victims of a deliberate attack on a military target.
(Based on Steinhoff, 2007, pp. 2–3)

Just war theory is a project, in philosophy, which considers the justifiability of war and killing in war, and concludes that there are occasions when it may be justified. Any theory that says that there can be a just war, even if only in theory, is a just war theory. Any sustained argument about the conditions of a just war is a contribution to just war theory. This is not a historical tradition, but (merely) an area of philosophy.