According to Lawrence Keeley, "90-95% of known societies engage in war". Why? What compels homo sapiens to kill each other? Why do we fight? Part one will describe two hypotheses.
War is Rational:
Sun Tzu argued that political struggles would eventually lead to armed conflict. Clausewitz took this one step further by saying that "war is a mere continuation of policy by other means". Machiavelli completed this entire line of thought by saying that war was the most efficient means of attaining any political goal.
War is Inevitable:
Hobbes argued that humans are inherently violent. Raymond Dart and Robert Ardrey found a scientific basis for this by claiming that homo sapiens became the dominant humanoid through their martial prowess (and we have kept this prowess ever since). Another group of philosophers believe that war can be attributed to the reckless aggression caused by testosterone in males.
For more information, read:
Sun Tzu's Art of War
Clausewitz's On War
Machiavelli's The Prince
Hobbes' LeviathanMilitary History Podcast is sponsored by Armchair General Magazine