In the history of war, religion, culture, and law have all played a role in conflict resolution. Pre-industrial wars focused on livestock and precious materials, while modern conflicts have increasingly focused on resources, like oil and minerals. Many believe that world populations will increase in the future, creating a shortage of these resources and increasing the risk of war. These factors will undoubtedly contribute to future wars, but the best way to avoid them is to prevent them before they start.

Despite the fact that philosophical discussion of war is a broad area of study, it is vital to distinguish between different schools of thought. For instance, while the definition of war can capture a clash of arms, it is also possible to define war as a state of mutual tension, a threat of violence, or a declaration by a sovereign body. Philosophers from various sub-fields are aware that war has a profound influence on human behaviour and expectations. Thus, writings about war typically have a normative component, as ideas of war can be self-fulfilling prophecies.

Modern uses of the term “war” may imply a clash between the early definitions, and may unwittingly incorporate conceptions of particular political schools. A more accurate definition of war would be a conflict between two or more groups, or between two or more species. The use of this term has also been extended to non-traditional conflicts, such as the conflict over religion. It can also refer to a conflict that centers around good and evil, as well as a political or ideological ideology.

Although we are conditioned by our circumstances, our human freedoms and the freedoms of our peoples have been at stake in wars for centuries. In modern times, the very concept of war has undergone a transformation. The terrorist attacks on September 11 changed the definition of war. Now, war is no longer confined to nation-states, but it is a relation between a state and its people. It is a global phenomenon.

Despite the horrific impact on millions of people, war continues to cause suffering throughout a society. While deaths during a conflict are just one component of war’s consequences, the psychological trauma and physical and economic infrastructure collapse can last generations. As a result, a society may be left without food and water, a lack of trust, and a breakdown of normal human relations. In wartime, women and children are the most vulnerable, and wartime is a major threat to their well-being.

Philosophers, particularly anthropologists, have also studied war and its causes. The first major theory of war, a branch of evolutionary psychology, argues that it is an extension of animal behavior, characterized by territoriality and competition. However, technological advances and evolutionary processes have accelerated human destructiveness. This theory has been advocated by Konrad Lorenz and criticized by John G. Kennedy. However, traditionalists have argued that war and peace have nothing to do with each other, and that they are indistinguishable.