The following rejoinders come to mind:  
  
1. "They do teach the history of medicine at HMS, as they do at most top med schools."
You can direct them to the following website as proof:
  
http://www.hms.harvard.edu/dsm/WorkFiles/html/academics/history/history.html  
  
2. "How many Nobel winners in medicine cite long-dead physicians as a way of confirming
the importance of their contributions?"  For the rhetorically impaired, you might just
point out that economists love to filiate themselves to HET when it helps their case to do
so, and that as long as they're making the ol' Argument to Authority, they and their
audience should at least know the basic facts.
  
Heath Pearson