A conspiracy theory is an explanation of an event or situation that invokes a conspiracy by sinister and powerful actors, often political in motivation, when other explanations are more probable. The word has a connotation, implying that the appeal to the conspiracy is based on prejudice or insufficient evidence. Conspiracy theories resist falsification and are reinforced by circular reasoning both evidence against the conspiracy and an absence of evidence for it, are re-interpreted as evidence of its truth, and the conspiracy becomes a matter of faith rather than proof.
Researchers suggest, on a psychological level, conspiracist ideation-belief in conspiracy theories -
can be harmful or pathological, and is highly correlated with psychological projection, as well as with propaganda, which is predicted by the degree of a person's Machiavellianism. Conspiracy theories once limited to fringe audiences have become commonplace in mass media, emerging as a cultural phenomenon of the late 20th and early 21th centuries.