For Alan No predictions "emerge" from a theory, or logic. A theory, or logic, as I am using the term, refers to a means of organizing one's thoughts about the observations one makes or can imagine. For a given set of observations or imaginations, the organization differs and, accordingly, the predictions one would make about future actions would probably differ from that which would result from a different means of organizing. But I am writing about theory in the abstract. To the vast majority of the users of the logic of choice, economics is not more than a combination of folk understanding and human psychology. I agree.Such economists define the term "choice" precisely as you say, in terms of a folk understanding and metaphysical beliefs. This is not meant to disparage economics. After all, we are all folks and we all rely on metaphysical beliefs. So we adopt a means of interpreting behavior that relies on some conception of a "common understanding," with variations that we introduce as we believe the situation dictates. Economists are no different from the woman walking down the street in this essential respect, although they certainly know a great deal more about how to organize their observations. Yes, people do make predictions all the time. But the issue here is about the nature of economics, not about the nature of sociology or of everyday life. It seems to me that you are writing about complexity. The kinds of predictions you are attributing to economics involve many choosers and, therefore, many complex minds that interact in complex ways before and during their choosing processes. Complexity (an overused term, I admit) certainly limits what economists can predict and understand. But it is unclear to me how your remarks are relevant beyond this. The law of demand is indeed implied by the logic of choice. However, one must specify the constraints on choice. Under specified conditions or assumptions, we deduce that individuals MUST choose to buy a larger quantity at a lower price. This logic is what I mean by the revolution with which we associate Gossen's name. P. S. I will be on the road for over a week and will probably be unable to continue this discussion until I reach my new destination. Pat Gunning