rational or irrational; irrational or rational

Rational is all that, all actions and all behavior which furthers the growth and development of a structure. Irrational are all such acts of behavior which slow down or destroy the growth and structure of an entity, whether that is a plant or whether that is a man. These things, according to the Darwian theory, have developed in the sense of being a safe part of the interests of survival of the individual and of the species. Hence basically they further the interests of the individual and of the species and therefore they are rational. Sexuality is perfectly rational. Hunger and thirst are perfectly rational. (…)

According to man one has to say: Irrational are not his instincts but his irrational passions. The animal has no envy, no destructiveness for its own sake, no wish to exploit, no sadism, no wish to control, all these are passions which are by and large hardly present at least in the mammals. In man they develop not because they are rooted in his instincts but because they are produced by certain pathological conditions in his environment which produce pathological traits in man. ― (1991d [1974]: Therapeutic Aspects of Psychoanalysis, in: E. Fromm, The Art of Listening, New York (The Continuum Publishing Corporation) 1994, pp. 72f.)