Flashbulb memories, grassy knolls and conspiracy theories

In an article in Prospect magazine titled “What were the causes of 9/11?”, the author, Peter Bergen, notes that the terrorist attacks of September 2001 gave rise to numerous conspiracy theories. Which is not really surprising, when people were struggling “to explain what otherwise appears inexplicable”. Discussing these theories, Bergen continues:

The usual suspects have been assembled on 9/11′s grassy knoll.

– a sentence packed with cultural allusions. Leaving aside “the usual suspects” (which in this case included the US government, the CIA, the oil companies, and others), why are they assembled on a “grassy knoll”? The answer takes us back to another of the key events of recent history: the assassination of President J.F. Kennedy on 22nd November 1963. Fifty years on, speculation about the circumstances of his death is as lively as ever. The verdict of the official inquiry was that Kennedy was shot from a nearby building by Lee Harvey Oswald acting alone (the so-called “lone gunman theory”), but conspiracy theories abound.

The best-known of these is that a different gunman (this time, not acting alone but as part of a wider plot) fired at Kennedy from a “grassy knoll” (a knoll is a small area of raised ground) close to the road on which the President’s car was travelling. The expression has become synonymous with conspiracies and cover-ups, as these examples from the corpus show:

The cause of the fire [the Great Fire of London] became the grassy knoll of late seventeenth-century conspiracy theorists.
The exact version of what happened next is lost in the mists of time, Lancashire football’s very own equivalent of the grassy knoll.
David O’Leary is quoted as saying that Jimmy will be sold “over my dead body”. Watch out for those grassy knolls, David!

Kennedy’s assassination is a prime example of what is sometimes called a flashbulb memory – an extremely vivid memory triggered by an exceptional and usually catastrophic event. It is linked to the question: “Where were you when you heard about X?”, where X (depending on where you’re from and how old you are) could be the death of Princess Diana, the assassination of John Lennon, or (for people in the Philippines) Typhoon Haiyan. For most older people, Kennedy’s assassination is the prototypical flashbulb memory, while for a younger generation, its place has been taken by 9/11.

Conspiracy theories are common to many of these “flashbulb” moments, but it is arguable that Kennedy’s shooting remains the most contentious of them all. The term conspiracy theory is first seen around 1900, but if you track its progress on Google’s Ngram viewer, you will see that it really took off in the decade following Kennedy’s death. And grassy knolls still pop up when people want to imply that an official explanation of some major disaster may not be all that it seems.