On the Starship Troopers controversy:  If a novel about a dedicated professional soldier does not leave the impression that warfare is the only real occupation for a real man, it's a failure.  I think Heinlein succeeded admirably, and the didactic parts of the books are both necessary and fascinating.  For the rest, I am on Poul's side.
 

Originally published in The Proceedings of the Institute for Twenty-First Century Studies #134, March 1960.