Endless.

From the Firing Line episode that aired December 3, 1981, guests Paul Hollander and Ernest Van den Haag discuss why intellectuals are so dumb ...

WFB: Is it safe to say that once you've learned political truths you are not again easily deceived?

PH: No, I'm afraid that's not quite true, because many people who learned something from the case of the Soviet Union fell again on China and on Cuba, and are now falling for Nicaragua right after Cuba; so I think this quest for a good society outside your own is endless.