A conspiracy theory is an explanatory or speculative hypothesis that suggests that two or more persons, a group, or an organization of having caused and/or covered up, through secret planning and deliberate action, an event or situation which is typically taken to be illegal or harmful.
A note on terminology: in this essay, "conspiracy theory" and "conspiracy culture" refer to thinking about actual conspiracies; "conspiracy theory criticism" refers to second-level thinking about conspiracy theory.
Review of Mark Fenster's Conspiracy Theories: Secrecy and Power in American Culture by Bart Beatty in Canadian Journal of Communication, Vol 24, No 4 (1999)