I once read or heard someone say that we often can learn more from the  
"mistakes" of the great thinkers of the past than from many of the  
"small truths" of modern economics.  
  
Someone may have mentioned a paper by Kenneth Boulding on why study the  
history of economic thought.  
  
There were some good points in that.  One might also point out that many  
of 'great' modern economists also did history of economic thought:  
Samuelson, Hicks, Baumol, Leontief, Hayek, etc.  
  
One issue that may be worth considering is whether the history of a  
field of study has different implications depending on whether or not  
the object of study in that discipline is one that changes over time  
(and whether that change is relatively fast-paced and significant).  
  
Mat Forstater