..or much of any other government-related position. Stephen Walt gives a list of the 10 Commandments--the 10 "thou shalt not hold or even consider" positions that are considered outside of "acceptable" foreign policy discourse. I've given serious consideration to ALL of them at one time or another. Probably about half of them are things I believe today.
This reminds me of when I was a very young research analyst, and after handing in a report I had out a lot of work into, my boss (for whom I had and still have the greatest respect) returned it with the comment
"Well thought out. Almost certainly true. Don't ever say it again."
I think that was the point I decided I'd get out of professional consulting and focus on the university. University political science departments have their own taboos, but once you get tenure you are less vulnerable to sanction. And officially, at least, every idea is supposed to be considered on its merits--even the "unacceptable" ones.