A Qualitative Theory of Cognitive Attitudes and their Change

Since the seminal work of Hintikka on epistemic logic [28], of Von Wright on the logic of preference [55, 56] and of Cohen & Levesque on the logic of intention [19], many formal logics for reasoning about cognitive attitudes of agents such as knowledge and belief [24], preference [32, 48], desire [23], intention [44, 30] and their combination [38, 54] have been proposed. Generally speaking, these logics are nothing but formal models of rational agency relying on the idea that an agent endowed with cognitive attitudes makes decisions on the basis of what she believes and of what she desires or prefers. The idea of describing rational agents in terms of their epistemic and motivational attitudes is something that these logics share with classical decision theory and game theory. Classical decision theory and game theory provide a quantitative account of individual and strategic decision-making by assuming that agents' beliefs and desires can be respectively modeled by subjective probabilities and utilities. Qualitative approaches to individual and strategic decision-making have been proposed in AI [16, 22] to characterize criteria that a rational agent should adopt for making decisions when she cannot build a probability distribution over the set of possible events and her preference over the set of possible outcomes cannot be expressed by a utility function but only by a qualitative ordering over the outcomes.