Psychologists such as E.F.M. Durban and John Bowlby have argued that human beings, especially men, are inherently violent. While this violence is repressed in normal society, it needs the occasional outlet provided by war. This combines with other notions such as displacement, where a person transfers their grievances into bias and hatred against other ethnic groups, nations, or ideologies. While these theories may have some explanatory value about why wars occur, they do not explain when or how they occur. In addition, they raise the question why there are sometimes long periods of peace and other eras of unending war. Nor do they explain the existence of certain human cultures completely devoid of war. If the innate psychology of the human mind is unchanging, these variations are inconsistent. A solution adapted to this problem by militarists such as Franz Alexander is that peace does not really exist. Periods that are seen as peaceful are actually periods of preparation for a later war or when war is suppressed by a state of great power, such as the Pax Britannica.

If war is innate to human nature, as is presupposed by many psychological theories, then there is little hope of ever escaping it. One alternative is to argue that war is only, or almost only, a male activity, and if human leadership were in female hands, wars would not occur. This theory has played an important role in modern feminism. Critics, of course, point to various examples of female political leaders who had no qualms about using military force, such as Margaret Thatcher, Indira Gandhi or Golda Meir.

Other psychologists have argued that while human temperament allows wars to occur, this only happens when mentally unbalanced people are in control of a nation. This school of thought argues leaders that seek war such as Napoleon, Hitler, and Stalin were mentally abnormal, but fails to explain the thousands of free and presumably sane men who wage wars on their behalf.

A distinct branch of the psychological theories of war are the arguments based on evolutionary psychology. This school tends to see war as an extension of animal behaviour, such as territoriality and competition. However, while war has a natural cause, the development of technology has accelerated human destructiveness to a level that is irrational and damaging to the species. Humans have similar instincts to that of a chimpanzee but overwhelmingly more power. The earliest advocate of this theory was Konrad Lorenz. These theories have been criticised by scholars such as John G. Kennedy, who argue that the organised, sustained war of humans differs more than just technologically from the territorial fights between animals. Ashley Montagu strongly denies such universalistic instinctual arguments, pointing out that social factors and childhood socialisation are important in determining the nature and presence of warfare. Thus while human aggression may be a universal occurrence, warfare is not and would appear to have been a historical invention, associated with certain types of human societies. Others have attempted to explain the psychological reasoning behind the human tendency for warring as a joined effort of a class of higher intelligence beings at participating in, experiencing and attempting to control the ultimate fate of each human, death.

In the fictional book Nineteen-Eighty-Four, author George Orwell talks about a state of constant war being used as one of many ways to distract people. War inspires fear and hate among the people of a nation, and gives them a "legitimate" enemy upon whom they can focus this fear and hate. Thus the people are prevented from seeing that their true enemy is in fact their own repressive government. By this theory war is another "opiate of the masses" by which a state controls its people and prevents revolution.

The Italian psychoanalyst Franco Fornari, a follower of Melanie Klein, thought that war was the paranoid or projective “elaboration” of mourning. (Fornari 1975). Our nation and country play an unconscious maternal role in our feelings, as expressed in the term “motherland.” Fornari thought that war and violence develop out of our “love need”: our wish to preserve and defend the sacred object to which we are attached, namely our early mother and our fusion with her. For the adult, nations are the sacred objects that generate warfare. Fornari focused upon sacrifice as the essence of war: the astonishing willingness of human beings to die for their country, to give over their bodies to their nation. Fornari called war the “spectacular establishment of a general human situation whereby death assumes absolute value.” We are sure that the ideas for which we die must be true, because “death becomes a demonstrative process.”

Source : http://en.wikipedia.org