From Dualism to Pluralism: The Third World in Judgment Under Uncertainty

Recent studies have shown that judgments under uncertainty are biased. That is, judgments in which uncertainty is involved deviate systematically from the norms of statistical theory. These biases are observed when people solve deductive paper-and-pencil problems intuitively, i.e., without conceptual and computational aids. This article examines the relevance of these biases. In which world are the judgments (and the biases) relevant, in the world of concepts and principles or the world of objects, events and people? The well-known “cab problem”, in which people are apt to ignore the impact of base-rates, was chosen as an illustrative example. - It was argued that people err in a world of concepts and scientific principles, or what Popper called “the third world”. Thus, it becomes necessary to adopt a pluralistic view: World 1 is the world of physical objects and states, World 2 is the subjective world (perception, thinking, dispositions to act), and World 3 is the world of scientific concepts, problems and theories. Bayes' rule, which is an adequate rule for solving the cab problem, belongs to World 3. Although the context of the cab problem refers to World 1 (cabs, an accident, visibility conditions, etc.) the norm (Bayes' rule) belongs to World 3. Thus, it is “our second world grasp of the third world” that is biased. If and how our biased grasp of World 3 affects thinking and acting in World 1 (the ecology) is not answered by the studies of judgment under uncertainty. In fact, these studies demonstrate the necessity of making clear what of World 1 and World 3 is under consideration. On the whole, the pluralistic view brings to the fore the question of how “our second world grasp of the third world” affects our interaction with World 1. - The notion of man as an intuitive scientist and the role of education were discussed from the pluralistic point of view.