And yet, you did not answer the question.
I answered
What do we know with absolute certainty?
The institutions in USA are corrupt, they lie, and manipulate the truth.
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Your reply, "1. Lee Harvey Oswald, by himself and unassisted shot and killed John F. Kennedy." -- this holds almost no weight, these days. Everything is questionable in the post Iraq-War lies of Bush. That was your president! Bush confidently lied to the world, assured of no consequences. Because that's what the institutions have done to their own people for so long there. Facts are easily manipulated in USA, and if not, then they're invented. Just another event in the procession of evil that has taken place, on 11/22/63, and since.
Where do you think USA stands right now in the world, a trusted ally? a trusted partner? a joke of a nation full of people twisted and manipulated by its own media?
Your institutions are not fit to serve the people and I don't blame the calls to burn it all down and start again. USA is almost done. I would ideally like to see a truth curtain go up between the UK and USA. Something similar to what China uses to keep themselves being also being imploded by American stupidity. They encourage their kids to be doctors and scientists. Not twerking transexuals. To have almost all cultural influences of USA kept away from vulnerable minds here I think would be appropriate.
The assassination of JFK and the continual crediting of a lone shooter scenario (by some) are just another (of many) ticking time-bomb's when it comes to USA's home-truths. I guess that's brought out in the denial of releasing the files regarding the assassination, why else? American's maybe cannot handle the real truth(s) of their nation. Exceptional, willful, ignorance!