Time and decision

The lecture deals with the problem of modelling time in decision processes. It is divided into three parts. The first part gives a survey of the concept of time in the history of thought and three concepts are identified: physical, perceived, structure of possibility. Then a short survey of the consideration given to time in ancient and modern logic. It is shown how modern model logic has produced a number of formalized languages which take into account temporal evolution and is providing a substantial back-up to the simulative languages of A.I. The second part analyses the time structure of decision making. With reference to a model “decision maker — system —ambient”, the times of the three terms of the model are discussed. The time of d.m. is shown to present all three aspects identified in the history of thought. The time of the systems or time horizon of the decision, is discussed under the aspects of perceived versus objective time, values in time, advantages and disadvantages of long-term vs. short-term decisions. The time of the ambient is considered in relation to the temporalized complexity of the world. The third part deals with the connections of time with uncertainty and with rationality. Uncertainty is discussed from the logical and informational points of view. A link is suggested between time and the fuzzy presentation of future events. Strategies for splitting the time horizon to better model uncertainties are also examined. Then the connection between the consideration given to time and the type of rationality adopted, sequential or synoptic, are discussed.