In his book The Anatomy of Human Destructiveness, Erich Fromm provides an analysis of human aggression. He discusses the differences between aggression in animals and in humans, and discusses how the specifically human forms of cruelty are connected to existential needs.
Fromm delineates three important existential needs: the need to be one with the world and to overcome existential loneliness, the need to have an effect on the world, and the need for stimulation. It becomes clear that for each existential need there is a healthy way and a destructive way to satisfy it.
With respect to the need to be one with the world, the healthy way to deal with it is to overcome existential loneliness through love and connection to others. Most religions proclaim this as the ultimate goal, exemplified by mystics like Jesus and the Buddha. But existential loneliness can also be alleviated by narcissism: by setting oneself at the center of the universe, the universe is identified with one’s self. This is usually accompanied by tyrannical, sadistic control over the world. Even more dangerous, the existential problem can be solved by destroying all others. Existential fear and feelings of powerlessness are alleviated by destroying that which is separate from the self.
The need to have an effect on the world can be satisfied by loving and nourishing others, but it can also be satisfied by controlling, hurting and destroying them.
Stimulation can be achieved through creative activity, but it can also be achieved through cruelty and destruction. The latter strategy is effortless, and requires neither sensitivity nor discipline. Some people are emotionally so numb, and so unable to be alive and creative, that the only way to feel something is to harm themselves or others. They may murder, just to feel alive.
Fromm notes that if we develop to the highest possible degree the constructive, loving way to deal with existence, we become fully human. Those who go into the opposite direction are existential losers. But both ways are adaptive to dealing with existential problems.
Sadism is an example of a destructive way to deal with existence. Fromm defines it as the need to wield absolute control over another living being. Absolute power means that the sadist can hurt and humiliate someone who is utterly at his mercy. This effectively makes the sadist a god, in relation to that person. As an example for a highly sadistic person, Fromm analyzes Stalin. Stalin often had the wives of his subordinates arrested, and he kept the husbands working for him, such that they had to see him every day. They had to condemn their spouses for their betrayal of communist ideals. It is not hard to imagine what satisfaction Stalin derived from wielding such absolute power over his subordinates. Sadists strive for power over people, because they are crippled themselves, unable to be truly alive.
Fromm calls love of life, growth, and creativity biophilia; attraction to control and destruction he calls necrophilia. According to Fromm, every individual is located somewhere on a continuous spectrum between biophilia and necrophilia. A biophilic person is someone who is drawn towards life and growth, who strives to develop love and connection. A necrophilic person is someone who is drawn towards control and destruction, who wants to subjugate others, to cripple them, to prevent their growth, and to destroy them. Many people are located somewhere in the middle, such that their destructive tendencies are somewhat mitigated by their potential for love. Some people, Hitler for example, are at the necrophilic extreme of the spectrum, mystics like Jesus or the Buddha approach the biophilic ideal.