Aggressionism is a philosophical theory that the only real cause of war is human aggression, which refers to the "general tendency to attack members of one's species."[1] It is argued that aggression is a natural response to defend vital interests such as territory, family, or identity if threatened.[1] This theory has dominated much evolutionary thought about human nature.[2]
Many evolutionary biologists discount aggressionism as it promotes human extinction through war.[3] The idea is that if homicide was the norm, the human species would have wiped itself out millions of years ago.[3] There is also the claim that aggression is not a universal instinct in the animal kingdom. However, some sources note that aggression serves the animal kingdom well since it brings the balanced distribution of animals of the same species over the available environment and that it can be viewed as a universal, externally directed drive that is possibly connected to a survival instinct.[4]