Just an example, if an alien did it and there is proof or big signals of evidence, a person who has cognitive dissonance, will ignore it, because the person has the assumption aliens does not exist, and its crazy to believe in aliens because the majority does not believe in aliens.
First show that this is actually the case.
Just the same with a lot of debunkers. They have the assumption, the government will never do that or its crazy they used planes for there targets
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I have no such assumption, Govs have and continue doing bad things.
My interest lies in what twoofers present as evidence and that I can see is not what they claim it to be.
So the new information, that contradicts their believe in the official story, they will ignore no matter there are signs of evidence or something else.
I have a training in science and work full time in engineering. Weird things happen all the time. I don't just pretend they didn't happen, I find root cause and fix them.
If the US gov wanted to MIHOP 911 they would simply have sent a undercover CIA guy to suggest the idea to Osama. It was a simple idea, with the only normally tough part being finding people who wanted to die for their cause. Osama had those by the dozen so all he needed were 4 that were smart enough to be able to fly a plane.........he found them and the rest is history. the other hijackers wouldn't even have to know what was planned (though it appears they did) for it to work.......4 suicidal nuts and a little money and you have 911.