ABSTRACT
Many economists still accept the assertions of Marschak (1954) that 'uncertain knowledge is not ignorance' and 'empirical social science consists of statements about probability distributions'. The potential invalidity of such strong assertions is at the heart of the wide range of radical views reported in the four sections below. Our discussion considers views which have been associated with major challenges to the primacy of conventional probabilistic-based perspectives, giving more attention to the recognition of vagueness, imprecision, imagination and other aspects of mental activity, contextual issues (including evolving goals, particular circumstances and information), and the troublesome impracticality of applying probability theories and some experimental evidence to major decisions and risk evaluations covering substantial hazards.
