Ethics examines war in terms of what is morally right or wrong, and different ethical perspectives offer various views on when and how war can be justified. One of the most well-known ethical frameworks is Just War Theory, which outlines the conditions under which war can be morally justified. According to this theory, war should only occur for a just cause, such as defending against aggression or protecting innocent lives. It must be declared by a legitimate authority, such as a government, and fought with the right intentions, aiming for peace and justice rather than personal gain. War should also be a last resort, with all peaceful alternatives exhausted, and it must have a reasonable chance of success. Furthermore, the violence used in war must be proportional to the harm it seeks to prevent, ensuring that excessive force is avoided. During the war, combatants must distinguish between military targets and civilians, avoiding harm to innocent people whenever possible.

On the other hand, Pacifism argues that war is always morally wrong. Pacifists believe that conflicts should be resolved without violence, advocating for non-violent methods like negotiation, diplomacy, or civil disobedience. For pacifists, war, regardless of the circumstances, is never a morally acceptable option because it leads to suffering and destruction that can be avoided through peaceful means.

In contrast, the ethical perspective of Realism suggests that war is a natural and sometimes inevitable part of international relations. Realists emphasize that states are primarily driven by self-interest and the pursuit of power, which often leads to war. According to realism, moral concerns may be secondary to national security and survival, and the ethics of war are often shaped by the political and strategic interests of states.

Lastly, Consequentialism, particularly utilitarianism, evaluates war based on its outcomes. From this perspective, a war can be justified if it results in the greatest benefit for the greatest number of people. Consequentialists argue that the ends can justify the means, meaning that even if war involves significant harm, it may be morally acceptable if it produces a better outcome for the larger population.

Each of these ethical frameworks provides a distinct perspective on war, examining its morality based on causes, intentions, outcomes, and the methods used in conflict.