Gambles which induce the decision-maker to experience ambiguity about the relative likelihood of events often give rise to ambiguity-seeking and ambiguity-avoidance, which imply violation of additivity and Savage's axioms. The inability of the subjective Bayesian theory to account for these empirical regularities has determined a dichotomy between normative and descriptive views of subjective probability. This paper proposes a framework within which the two perspectives can be reconciled. First, a formal definition of ambiguity is given over a continuum ranging from ignorance (...) to risk, and including ambiguous contexts as subsets. Second, it is shown that the systems of inductive logic account for the effects of ambiguity. Then, Carnap's X-system is applied as a psychological model and compared to Einhorn and Hogarth's non-normative psychological model. Finally, the implications of this research to the modeling of subjective probability judgements are discussed. (shrink)

Findlay and Lumsden have proposed a model of creative potential which accounts for divergent thinking but not for convergent thinking. This limitation impedes the applicability of the model to scientific creativity, where competence and thus convergent thinking play a fundamental role since the early stages of creation. This limitation is a natural consequence of the fact that Findlay and Lumsden's model is purely intrapsychic. This paper proposes a model of scientists' creative potential which accounts for both divergent and convergent processes. (...) First, drawing from Csikszentmihalyi's and Kuhn's theories, scientists' creative potential is defined as a matching between the cognitive structure and the epistemic and social structure of the domain. Second, based on this sociopsychological definition, an extension of Findlay and Lumsden's model is proposed. The model states that the highest creative potential is achieved by those scientists who deeply understand the core of the domain and still have cognitive power to access, and experiment on many ideas that are not presently included in the domain. The new model is shown to have greater explanatory power than Findlay and Lumsden's model and to include the latter as a limiting case. (shrink)