For the first four, maybe, but not for the fifth (one reason why I stumbled over its inclusion). What these "great outbursts" are supposed to have in common is world-historical significance, which in every case except 1980s Iran means that a great power is involved. As for the Khmer Rouge, if I were to write a history of the past century organized around these five outbreaks, I'd make them a postscript to "1960s China".
When we get to the present day, I'm not convinced that my fifth item warrants inclusion. Both sides of American politics on occasion accuse the other of conspiracy and of baseless conspiracy theorizing, but this is a chronic condition of politics in all societies. I think what has happened is that a certain type of conspiracy - stealth WMD attacks by an invisible enemy - has become the threat around which the world is reorganizing, and so the conspiracist dimension of politics has become central in a way that it wasn't before. Thus people argue about whether Iraq sponsored al Qaeda, whether Iraq sent the anthrax, whether the Bush administration cynically promoted these ideas in order to engineer the war, whether they fell prey to conspiracist thinking and fought the wrong war, whether the anthrax was meant to frame Iraq or to stimulate biodefense research, etc. Perhaps one can similarly find a structural reason why conspiracism became prevalent and relevant on those earlier occasions too.
You replied: For the first four, maybe, but not for the fifth (one reason why I stumbled over its inclusion).
That was why I asked. The present-day U.S. didn't seem to fit the pattern (unless you were to propose one of those bizarre 9/11 conspiracy theories).
What these "great outbursts" are supposed to have in common is world-historical significance, which in every case except 1980s Iran means that a great power is involved. As for the Khmer Rouge, if I were to write a history of the past century organized around these five outbreaks, I'd make them a postscript to "1960s China".
I think the Khmer Rouge's devastation of their own country resonated with the world in a way out of proportion with Cambodia's actual influence on world affairs. But you're probably right in grouping it with China's so-called Cultural Revolution.
In the same way, Iran really is part of a larger conspiracy-theory phenomenon that extends through much of the Muslim world, just as Pipes pointed out. Moreover, to the extent that this is based in anti-Semitism, there is an overlap with Nazi Germany (witness the re-emergence of the "blood libel" claims or the popularity of the Protocols of the Elders of Zion, in places like Saudi Arabia and Egypt).