Fears of a petty conspiracy – a political rival or business competitor plotting to do you harm – are as old as the human psyche. But fears of a grand conspiracy – that the Illuminati or Jews plan to take over the world – go back only 900 years and have been operational for just two centuries, since the French Revolution. Conspiracy theories grew in importance from then until World War II, when two arch-conspiracy theorists, Hitler and Stalin, faced off against each other, causing the greatest blood-letting in human history. This hideous spectacle sobered Americans, who in subsequent decades relegated conspiracy theories to the fringe, where mainly two groups promoted such ideas.

The politically disaffected: Blacks (Louis Farrakhan, Cynthia McKinney), the hard Right (John Birch Society, Pat Buchanan), and other alienated elements (Ross Perot, Lyndon LaRouche). Their theories imply a political agenda, but lack much of a following.

The culturally suspicious: These include "Kennedy assassinologists," "ufologists," and those who believe a reptilian race runs the earth and alien installations exist under the earth's surface. Such themes enjoy enormous popularity (a year 2000 poll found 43 percent of Americans believing in UFOs), but carry no political agenda.
The major new development, reports Barkun, professor of political science in the Maxwell School at Syracuse University, is not just an erosion in the divisions between these two groups, but their joining forces with occultists, persons bored by rationalism. Occultists are drawn to what Barkun calls the "cultural dumping ground of the heretical, the scandalous, the unfashionable, and the dangerous" – such as spiritualism, Theosophy, alternative medicine, alchemy, and astrology. Thus, the author who worries about the Secret Service taking orders from the Bavarian Illuminati is old school; the one who worries about a "joint Reptilian-Bavarian Illuminati" takeover is at the cutting edge of the new synthesis. These bizarre notions constitute what Michael Kelly termed "fusion paranoia," a promiscuous absorption of fears from any source whatsoever.[44]