I think that Dennis Robertson had a very good answer to this   
question. Why teach the history of thought? Because: "highbrow   
opinion is like a hunted hare; if you stand long enough it will come   
back to the place it started from".  
  
In other words, history of thought may be useful in order to avoid   
"the attractive Anglo-Saxon kind of unnecessary originality" (which, in my view, is by no
means an exclusive character of the Anglo-Saxon culture).
  
Lilia Costabile