In the history of human society, War has been one of the most enduring and common forms of international relations. The nature of war has evolved throughout time and across eras, but the basic form and character of war remains essentially the same: a military confrontation between state and non-state actors on ideological or ethnic grounds.

The ethics of war are based on three factors: Just Cause, Legitimate Authority and Right Intention. Ideally, they are all satisfied so that there is no justification for fighting and the resulting injuries are morally proportionate to the good achieved (Waltz 2001).

Just Cause

The just cause of a war is an attempt to avert harm. In some cases, this can be achieved through a just and morally legitimate means of violence such as retribution, but most often it is a result of the failure of other means to avert harm or even prevent it in the first place.

Legitimate Authority

The state is the primary entity that engages in war. Its legitimate authority is its right to act in pursuit of its interests. The state may not be invincible, but it is able to exert sufficient control over its enemies to avoid unnecessary and unjustified harms.

This legitimate authority can be exercised through a wide variety of means, including negotiation, threats, force, diplomacy and coercion. It can be exercised by a military authority or by an individual, but it is usually exercised through the use of force.

Having legitimate authority is not enough to make a war just, though it can be an important staging-post on the way to judgements of necessity and proportionality. Alternatively, the legitimacy of a state’s authority can be demonstrated through its compliance with the international laws of war.

Just Intention

The just intention of an actor involved in a war is that it should not knowingly engage in an action that would lead to unnecessary and unjustifiable injury. This is a critical part of the morality of war, and it is crucial to the evaluation of necessity and proportionality.

Proportionality

The proportionality of a war must be assessed by determining whether the morally weighted goods achieved in war outweigh the morally weighted bads. This can be done through a number of different methods, but it is usually best to begin by examining the morality of the actions that are intended to achieve the just cause.

The morality of war has its origins in the idea that humans are motivated by their own altruistic desires to protect others and to defend their own societies from danger or harm. The fact that this impulse has been the primary driving force for most of mankind’s history is not a surprise; it is a natural and universal aspect of humanity. However, it is also a complex phenomenon that can be difficult to fully understand and resolve.