Politics in Minutes (2016)

Just war theory

There has always been conflict between nations and, despite an almost universal condemnation of the use of force, international conflicts frequently result in war. But can war ever be justified? This was a question first addressed by medieval Islamic and Christian philosophers, who came to the conclusion there is such a thing as a ‘just war’, if it satisfies three main criteria: it must have proper authority (declared by a state or ruler); just cause (to recover something that has been taken); and right intention (the goal of restoring the peace).

The idea of jus ad bello - the right to go to war - later became a matter for international agreement rather than moral philosophy, and more detailed criteria for justifiable use of force were established. These included the ideas of proper authority, just cause and right intention, but also added principles of proportionality, probability of success and last resort. The rules of jus in bello regulating conduct in war were internationally agreed by a succession of Geneva Conventions.