The Term “Conspiracy Theory” Was Invented by the CIA In Order To Prevent Disbelief of Official Government Stories
Ron Unz reports on the cold shoulder given to an extensively researched book that concludes that World War II hero General George Patton was murdered by the CIA because he became a powerful critic of Washington. http://www.unz.com/runz/was-general-patton-assassinated/ 
The book was ignored because the US media and public have been programmed to regard the US government as a truth-teller and those who expose government crimes as “conspiracy theorists.”
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.