Isn't the issue discussed in this thread essentially equivalent to    
the question of whether or not economics is a discipline progressing    
in a linear and cumulative way --that is, with new bits of knowledge    
added to a definitive corpus? If the answer is yes, history of thought   
would be a redundant pastime adding no useful knowledge to the    
discipline; if the answer is no, then there is a scope for HoT, for    
the simple fact that there is no way now to know whether we ('we'    
whom?) are (now) on the right track or not.  
  
Unless we take the history of economics to coincide with the history    
of analytical instruments and theorems (by the way, did anyone notice    
that the best article prize given by eshet is called "history of    
economic analysis"?), which one could maintain that do improve and    
cumulate, one could easily argue that the history of economic (or any    
other discipline, for that matters: mathematics included) is far from    
linear, but is characterized by unexpected return of old issues and    
viewpoints (this sentence, cited by memory from an Italian    
translation (!!), was used by the Nobel prize Ilya Prigogine in    
association with the historian of science Isabelle Stengers to    
describe the history of physics).  
  
Daniele Besomi