As the arguments about assumptions and premises between John M. and Fred F. seem  
to get tangled up in verbal knots,  I have a concrete suggestion. We should go  
back to John Stuart Mill's On the Definition of Political Economy; and on the  
Method of Investigation Proper to it. His thesis is that any science, including  
the inexact moral sciences, must use the deductive method to discover the  
regularities that can be resolved to a few basic principles derivative of the  
elementary laws of human nature.  But he is equally convinced that to make it of  
any use in policy formation (which he termed the art of political economy) to  
improve society (a goal with which we all agree), this must be followed by a  
posteriori application of the theorems derived from a priori reasoning.  
                   
He called the a posteriori method of "great value in moral sciences, namely, not  
as means of discovering truth, but of verifying it, and reducing to the lowest  
point the uncertainty....arising from the complexity of every particular case."  
Mill made the behavioral  assumptions of: 1) desire for wealth, 2) aversion to  
labor and 3) present enjoyment of costly indulgences as suitable for what he  
termed the economic department of life. And he was meticulous in recognizing the  
cultural difference among groups of people when he wrote about the complexity of  
social phenomena and "disturbing causes". Too bad the trajectory of economics  
since his contributions took the formalist, deductive path and ignored some of his  
most valuable ideas.  
                   
Going back to the questions raised in some posts about the definition of  
economics, Mill defines political economy as the "science which traces the laws of  
such of the phenomena of society as arise from the combined operations of mankind  
for the production of wealth, in so far as those phenomena are not modified by the  
pursuit of law of any other object".  Mill's relevance to the present state of  
economics afflicted with deep fissures seems powerful.  
                   
Sumitra Shah