Bob -- > "Rational" has always meant to me that a decision maker has > preferences over the set of possible choices or outcomes and acts > according to his preferences. >Whether those preferences are > representable by a utility or expected utility is another matter. > Rational could also be defined in terms of revealed preference: Can > one use observations of a decision maker's actions and deduce that > his actions are consistent >with acting in accordance with a > preference relation.
Your statements examplify my point: neither of these definitions of "rational" accord with the usage of the word in the philosophy of argumentation, usage which goes back at least to Aristotle. > I see little evidence or need to identify "rational" with the >reparability of preferences into beliefs and utility of outcomes. But >operationally, we need some restrictions on "preference relation" to >have a meaningful testable theory. Thus we may posit some >consistency (transitivity) and some other meaningful axioms. >Otherwise Aristotle's definition is no more meaningful than >Lange's. If there were no paradoxes in the development of the axioms >of these utility theories, the resulting theories would be just as >vacuous. On the contrary, if rational behaviour is defined, following Aristotle, as behaviour for which an actor is able to provide reasons when questioned, then I should think this definition is quite operational. The definition says nothing about the nature, adequacy, optimality, or other properties of the reasons given or of the action-option selected, only that reasons can be provided. My point was not that such a definition leads to a better theory of decision-making than MEU (although it may do). My point was that economists and decision-theorists had taken a particular word and given it a different meaning. One has to wonder why they did this. A sociologist of economics might say the answer to this question is seen when certain behaviour is labelled as "irrational". > Arrow's social choice theory is a much stronger refutation of a > theory than a couple of curious paradoxes that lack universal > appeal. He shows >the inconsistency of a set of reasonable > axioms. So far, at least, such a refutation of individual decision > theory has not been forthcoming. I made no comment on Arrow's social choice theory itself. I only noted that he uses the word "rational" to refer to a particular ordering of action-options, rather than to the giving of reasons for actions. -- Peter
