The current status of the psychoanalytic theory of instincts appears ill defined and uncertain. Accordingly some of our basic concepts and postulates concerning the theory of life and death instincts are critically examined. Freud's views regarding the death instinct seemed to have been influenced by the biological theories current at that time. These theories were largely based on the physics of closed systems. In an attempt to explain the nature of life processes, the principle of entropy

(the second law of thermodynamics), valid for closed systems only, was extended to include organic systems. Since, however, life can occur only in open systems, the principle of entropy is not applicable under these circumstances.