A war is a state of intense violence and conflict, generally between states but also between groups within a state. A war involves the systematic use of violence and is usually characterized by the deliberate intention to kill people, destroy property and disrupt economic and social life. It is a serious, protracted human disaster that can be hard to come to terms with. It carries catastrophic consequences for individuals, families and whole nations. Death is the most obvious consequence but other effects include endemic poverty, malnutrition, disability and economic/social decline. War causes long term damage to human health, especially among children, and devastates the fabric of societies and communities. A recent survey in Afghanistan, Colombia, Liberia and Lebanon, for example, found that sixty-six percent of the population reported having a family member killed or injured during hostilities.

Modern scholars have struggled to explain the causes of War. Theories centring on man’s innate drives have been developed by ethologists drawing analogies with animal behaviour, and by psychologists and psychoanalysts. Some optimists believe that it is possible to prevent war by understanding the origins of human nature, while others are pessimistic about the avoidability of war.

In the last analysis, war is a rationalised form of violent collective action. It is organised to achieve particular objectives – protection, the acquisition of critical resources, power, prestige or legitimacy, a sense of honour and credibility, reaction to perceived injustice, ambition or opportunism – by means of specific techniques, military technology and tactics, political objectives, dynamic interaction between actors and chance and friction.

The strategic thinking that underpins warfare, both the rationalist position that a state can justify any war as a necessary means to an end and the Clausewitzian concept of the ‘duel of opposing forces’ is an attempt to understand the reasons for success and failure in armed conflict. Inevitably, such theories are based on assumptions about the nature of human beings that are implicit in and therefore often invisible to observers.

The underlying assumption is that war is inevitable because the world contains great powers, countries whose manpower and capacity to manufacture armaments far exceed that of any other. These countries will remain the dominant powers as long as they are able to develop their industries to a high level and keep their militaries ahead of those of other nations.