A conspiracy theory is an accusatio

A conspiracy theory is an accusation that a group or organization has colluded to cause or cover up an event or phenomenon. In recent decades the term has acquired a derogatory meaning of imagined conspiracies and not actual conspiracies.
It has been suggested that people believe in conspiracy theories to explain, for example, power relations in social groups and the existence of evil forces. Different types of conspiracy theories have been distinguished, ranging from those merely based on a hunch to ones backed by evidence; and from localized, single-event conspiracies to pervading universal phenomena. Jesse Walker has focused on the conspirators’ juxtaposition with society: above, within, or below and has also proposed the existence of benevolent, angelic conspiracies.
The evolution of conspiracy theory has been traced by some to its psychological and socio-political origins. Proposed psychological origins include projection; the personal need to explain “a significant event [with] a significant cause;" and the product of various kinds and stages of thought disorder, such as paranoid disposition, ranging in severity to diagnosable mental illnesses. Similarly, socio-political origins may be discovered in the need of people to believe in event causation rather than suffer the insecurity of a random world and universe.
Michael Barkun and others have debated the effect of conspiracism, a world view that places conspiracy theories centrally in the unfolding of history. Barkun says it has become “the dominant paradigm of political action in the public mind” squeezing out democracy. In much of human history political regimes have colluded to form real conspiracies within and without (e.g., Hitler and Stalin agreeing to divide Europe) and used conspiracy theory to manipulate their subjects