The sciences say little about what distinguishes man from animals. With the advent of science, the mode of human life was assimilated with life in the inclusive sense of the entity that refers to the ensemble of living beings. Life and death stand in a complementary relationship in the service of the principle of constancy. The dualism of the life and death drives was also intended to counter the vitalists' belief in a single and unique vital force determining the living world. Cybernetics or information theory has tried to impose another conception of living beings. Cybernetics announced the beginning of a conception treating both living beings and machines as self-organizational systems. Cognitivism is linked to a major signifier: an intelligent machine or programmable computer. Cognitive-behavioural techniques pay little attention either to the psychic structure of patients or to their history. Cognitive therapies require scarcely any empathy on the clinician's part.