The tools which have proved most fruitful in uncovering these motives are an array of post-psychoanalytic concepts and the student of psychohistory would do well to be acquainted with some of the basic concepts of psychoanalysis. It seems strange that this question should be answered in the negative that child rearing should be considered irrelevant to cultural evolution or history. However, we must bear in mind that it was not until the middle of this century that we acquired the tools for, and were able to begin the process of, looking candidly at childhood. Even drive theory, by positing essentially innate conflicts which do not derive from the child's environment, did not fully appreciate the relevance of child rearing. In the psychogenic theory of history, the kinds of trauma inflicted upon infants and children are central determinants in the evolution of human culture.
Fetal traumas are also crucial determinants.
Besides trauma theory and the tools of psychoanalysis applied to groups, psychohistorians also employ, inter alia, family systems theory, the study of group processes, neuro-biology, and fetal psychology. Using these tools, history and current events are examined through diaries, photographs, cartoons, art, biographies, and other materials. At times psychohistory overlaps anthropology, sociology, and political science, but views this material from a unique perspective. People who have been reared abusively, develop a self-loathing. The psychogenic theory of history posits an evolution in the direction of greater human compassion because of improvements in child rearing.