Dave Colander wrote  
In thinking about Robbin's definition, it is important to remember that  
he, like the classics, differentiated economics and political economy.  
Economics (the science) was the science of choice. Political economy was  
applied policy analysis. In his Ely lecture he made this clear. He  
agreed with JN Keynes, that political economy would be much broader and  
included many non-economic issues.  
  
  
Roy Davidson responding  
It is important to distinguish between economics and political  
economy.Contrary to the implication that political economy is somehow  
less scientific than economics, depending upon the definition of the two  
disciplines, the reverse may be the case.  
  
At least some classical writers have defined political economy as "a  
study of the natural laws relating to the production and distribution of  
wealth." Assuming this definition and economics as a study of choices,  
the latter would seem to be broader and less scientific.  
  
Roy Davidson