The Study of War is a vast, complex and ever-changing phenomenon. It is a subject that has been debated in many ways by diverse writers throughout history. For example, Cicero defines war as “contention by force,” Hugo Grotius writes that it is a “state of perpetual conflict between contending forces,” Thomas Hobbes describes it as a convulsive disease of the body politic, Karl von Clausewitz writes that war is politics by other means, and Denis Diderot says that it is a form of competition for control of resources, territory and conditions of life. It is important to be cautious when examining definitions of war, as they often mask a particular political or philosophical stance paraded by the writer. It is also essential to examine proposed definitions of war in terms of their logical validity and internal consistency.

Contemporary theories of war largely divide into three groups: those that attribute war to certain innate biological and psychological factors or drives, those that attribute it to social relations and institutions, and those that attribute it to man’s rationality and ability to control bellicosity. These theories range from those that seek to explain the cause of war in scientific and mathematical terms, such as those based on the principles of ethology, physics and mathematics developed by biologists and psychologists. The emphasis placed on these theories may, however, ignore the fact that some individuals and groups of humans are born with inherited pugnacity, and that man’s intellectual capacity to control this trait is dependent upon the cultural environment in which he or she is raised.

Another set of theories focuses on the nature and causes of war as it has evolved over time in response to changes in culture, technology, and economy. These theories often stress the introduction of new weapons systems, the advancement of transport and then powered flight, and the development of economic empires as key events that have changed war’s character. These arguments may also overlook the fact that civilians have always constituted the overwhelming majority of fatalities in most wars, including those in which explosive weapons are used in urban areas.

Finally, some scholars attempt to establish an ethical value in war, with the implication that if it is fought for the right reasons it can be morally justified. This view, like pacifism, is highly contentious and is largely dependent on one’s belief about a human’s ability to change his or her innate tendencies to violence. It is also largely dependent on a person’s beliefs regarding determinism, in that if the cause of war is irrevocably predetermined by genetic or biological factors, then it cannot be prevented. Nevertheless, this is not necessarily the case and some scholars believe that culture and education can help reduce a country’s propensity to go to war. This, in turn, will likely lead to a reduction in fatalities and injuries.