The truther narrative is that our own government did 9/11 as an excuse to invade iraq. So if that's not your claim then what is?
I don't even know who the truthers are.
My claim is that I spent a month carefully going over the 911 report to teach this as a case study in my forensics class and I discovered it was a horribly done investigation, truly stunning at what wasn't done. The explanation made no sense. Their were many tests that should have been done which weren't. Evidence was destroyed and even if you accept the official narrative of guys with box cutters did all this, they were dead when the investigation took place so they had nothing to do with that.
That is the "what" it is very easy to see the "what" not so easy to see the why.
I can tell you what happened as a result of the official narrative.
1. Patriot act was passed, greatly curtailing civil liberties and expanding the governments ability to become a tyrant.
2. We invaded Iraq which had nothing to do with the attack. That is generally agreed on by everyone.
3. We put our military in position in both Iraq and Afghanistan to control major oil and gas fields.
This does not mean that everyone who voted to invade Iraq had prior knowledge of 911, I suspect very few of them did, if any of them. Nor does it mean that when they voted to invade Iraq they knew that Iraq was innocent. It is very likely that the majority of them didn't.
However, the fourth thing that happened is definitely what I think was the goal. I think this because Dick Cheney said this almost 9 months prior to 911. He said that they needed a whole lot of money to completely overhaul our military with state of the art drones and robots and that the only way to get the American people to agree to this is if we had another Pearl Harbor event. (I paraphrased but this is what he said).
Therefore I do believe Dick Cheney was behind 911 and it was he who said the day of the attack that we needed to pin this on Iraq. I suspect almost no one else in government knew anything about this. Once the attack happened it would be easy to manipulate them.