Conspiracy theory
Conspiracy theories are a belief that a covert and deceptive organization or people is responsible for important world events, and that these people are hiding their own involvement, acting from behind the scenes and spreading misinformation. Usually, the term is used pejoratively, to denote irrational, paranoid and empirically unsupported beliefs that purport to describe world events through all-powerful unseen agents. These beliefs often fall foul of Occam's Razor, are unfalsifiable, often illogical, based on political presuppositions (often of an extreme kind: racist or anti-semitic). Similarly, those within political movements (of all stripes) which conspiracy theorists ally themselves with are often keen to distance themselves from conspiracism.
Conspiracy theories are often dominated by secret societies and groups: the Jews, international bankers, Masons, the supposed New World Order, fraternal groups like Yale University's Skull and Bones society, the Roman Catholic Church (or groups within the Church like the Jesuits or Opus Dei), the Knights of the Templars, the Bilderberger Group, the Rockefeller Foundation, leaders of the nations in the European Union, Satanists, the medical, psychiatric or legal professions, among many others. These groups are said to use power in all forms, dominating all institutions in society: schools and universities, the government, churches and religious institutions, the media, business and the military. These conspirers are said to operate in ruthless ways: playing ideologies and countries off one another, masking their true intent behind multiple layers of facade, and hiding their secrets both far out-of-sight in their eerie catacombs and secret crypts, and in plain sight in their public-facing symbols and the naïve dismissal of ordinary people.