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