“In 2013 Professor Lance Dehaven-Smith in a peer-reviewed book published by the University of Texas Press showed that the term “conspiracy theory” was developed by the CIA as a means of undercutting critics of the Warren Commission’s report that President Kennedy was killed by Oswald. The use of this term was heavily promoted in the media by the CIA. https://www.amazon.com/Conspiracy-Theory-America-Discovering/dp/0292757697/ref=sr_1_1?s=books&ie=UTF8&qid=1471971025&sr=1-1&keywords=Conspiracy+Theory+in+America
It is ironic that the American left is a major enforcer of the CIA’s strategy to shut up skeptics by branding them conspiracy theorists.”
https://www.paulcraigroberts.org/2016/08/24/the-term-conspiracy-theory-was-invented-by-the-cia-in-order-to-prevent-disbelief-of-official-government-stories/