In this paper we explore the idea of aggression as a defence against threats to the psychological self. This aspect of the self allows reflection about people in psychological terms and develops, in the first three years of life, through appreciation of mental states in the other. When the object is unpredictable or hostile, recognition of this is painful to the child, and his reflective function will not be adequately established. The defences of aggression or avoidance will be invoked very frequently. In time, aggression may become an organising influence in the construction of the self; pathological destructiveness then takes the place of emotional relatedness and concern for the other. Psychoanalytic treatment no longer works primarily by addressing conflict. Instead, particularly through interpretations of transference and countertransference, the analyst recreates an intersubjective process which enhances the patient's reflective self, this time in the safety of a benign relationship.