Fifty years after President John F. Kennedy's assassination, the belief that more than one person was involved remains strong. Based on our review of polls on a variety of conspiracy theories stretching back to World War II, we show that this conspiracy is the most widely held one in America. Here are some findings from our new AEI Public Opinion Study:
JFK: In an April 2013 poll, 59 percent said others were involved in a conspiracy to kill President Kennedy. Even as early as November of 1963, people had doubts as to whether Lee Harvey Oswald was the sole shooter. Sixty-two percent in 1963 told the National Opinion Research Center that other people were involved in the assassination.
Pearl Harbor: In the few polls we have, a sizable minority of the population believes President Roosevelt knew about the attack on Pearl Harbor in advance and used the attack as an excuse to go to war. Although we could find no polls from the time of the attack, a 1997 Scripps Howard and Ohio University Poll revealed that 16 percent thought it was very likely and 26 percent somewhat likely that Roosevelt knew in advance.
Aliens and Roswell: Polls taken by Roper Starch Worldwide from 1977 to 1999 show that around 20 percent believe UFOs exist. A similar proportion embraces the view that UFOs have landed in the United States at Roswell, New Mexico and that the government is engaged in a systematic cover-up of this event. A March 2013 Public Policy Polling survey found that 21 percent embraced this view.
MLK: Some believe that the assassination of Martin Luther King Jr. was carried out by the US government and argue that James Earl Ray was a scapegoat. In a 1976 Harris poll, 60 percent believed the assassination was the work of a conspiracy. In a 2008 CNN poll, 55 percent endorsed the notion of a conspiracy. African Americans are more likely than whites to believe his assassination was a conspiracy.
9/11: Pollsters have asked about several conspiracies surrounding the events of 9/11. In a July 2006 Scripps Howard and Ohio University poll, 16 percent said it was likely that the "people in the federal government either assisted in the 9/11 attacks or took no action to stop the attacks because they wanted to United States to go to war in the Middle East."
Obama's Birthplace: Even though a majority of Americans consistently tell pollsters that they think the president is a U.S. citizen, a substantial portion (as high as 39 percent in one poll) think Obama was born abroad. Republicans are more likely than Democrats to hold this view, but the proportion of Republicans who believe this has declined.
Quantifying the number of conspiracy theorists in America is not possible with survey questions asked at different points in time. We know that long-held deep suspicions of federal government power undergird some of the answers people give pollsters about these events. Softer questions that ask people if the government isn't telling the full story or if there is more to know produce stronger responses than questions about whether plots or schemes are afoot. Our collection of survey data in this new AEI Public Opinion Study suggests that with the exception of the Kennedy assassination, only around 10 percent generally believe in most conspiracies.
Karlyn Bowman is a Senior Fellow at the American Enterprise Institute, where Andrew Rugg is a research assistant.