dual instinct theory
in classical psychoanalytic theory, the view that human life is governed by two antagonistic forces: the life instinct, or Eros, and the death instinct, or Thanatos. This was a late theoretical formulation by Sigmund Freud, who held that “the interaction of the two basic instincts with or against each other gives rise to the whole variegation of the phenomena of life” (Beyond the Pleasure Principle, 1920).