Economic theory assumes that people behave rationally by trying to maximize utility or profit. Therefore, Becker (1962) considered in what way people might be defined as behaving irrationally & suggested 2 types of irrationality. A dichotomy of suicidal individuals, impulsive versus chronically disturbed, previously proposed by Lester (1988), is shown to parallel the dichotomy of irrational behaviour described by Becker. (3 refs.)