So, I think these are two questions.Only conspiracy I know of that has any merit is that the government knew it and let it happened.
I don't agree with that, but the other conspiracy all have gigantic logical holes.
For example, WTC 7 being a demolition: Why would they bother demolishing WTC 7, when they could've just flown a plane into it? It makes no sense. Controlled demolitions take a ton of explosives, and it'd be obvious when it was being setup.
My own theory is that they knew attacks were planned, but didn't have very good details of when and where. From what I remember, they had intel that said that Al Qaeda was planning to use planes as weapons, but didn't know when and where. It's not like they could ground all air traffic indefinitely on some possible plans, but they certainly should've done more to not allow weapons on planes and change the plans after a hijacking to not give in and fight back. Why they fucked up? I say laziness and incompetence. Wouldn't be the first or last time the government was incompetent.So, I think these are two questions.
Foreknowledge. We know that diplomats from the illegitimate 'Saudi Arabian' government were used to funnel funds to the hijackers. We know that employees of Urban Moving Systems, one of several moving companies being run as a Mossad front, were in place to record the attack on the first tower, something that came out of nowhere for just about everyone else on that day. We know that another such Mossad front even provided logistical support for one of the terrorists to move from New Jersey to Florida. Given all that, guys like Dick Cheney and Wolfowitz almost certainly knew.
Meanwhile the CIA's Alec Station was aware of the presence of Nawaf Alhamzi and Khalid Al-Midhar- who had been under their surveillance for years- in the US, but neglected to inform the FBI about this despite there being well-defined protocols in place for doing so (the idea that the Patriot Act was required to 'break down a wall' in intelligence is an outright lie). This despite the fact that Al-Midhar had even been involved in the bombing of the USS Cole. Perhaps they did this because they intended to turn one or both as double-agents, perhaps it was because they were under the influence of foreign agents, perhaps they were just lazy. The laziness explanation sounds rather implausible.
Did Bush know? Maybe, maybe not. Does it really matter? Probably not, people he put in positions of responsibility certainly knew.
This is only reinforced by the failure of the Bush regime to seriously target Bin Laden after the attacks. The Taliban government, horrified by the crimes that this already rather unpleasant Saudi cosmopolitan guest within their country had committed, offered to apprehend him and turn him over to any Islamic government to be righteously tried. Had Bush accepted this, Bin Laden could have received the punishment that he deserved rapidly, and with a fair opportunity to put forth his case.
Of course, as part of that, he might have revealed the governments who supported the plot, and that couldn't be allowed to happen, so it was rejected. Very suggestive.
And in the same way- the opportunity to capture Bin Laden escaping Tora Bora was deliberately sabotaged. If you're trying to capture the man you blame for the most notorious attack on your country, do you send literally tens of (admittedly elite) Delta operators, plus some random locals who might as well have been working for the enemy but were paid off by Green Berets so were supposedly on the American side? Of course not. If they'd intended to capture BL, the request of the commander on the ground for a few hundred Rangers to set up observation points on the border would have been granted. Forget a few hundred, they'd have sent the entire Ranger Regiment and every Airborne Division to first fence off the border with bodies and then run BL to ground. Again, very suggestive.
Demolition wise- who knows. Even the main trade towers, which were hit by planes, were difficult targets for inexperienced airline drivers. I believe there is evidence that contractors who had no authorization to operate in the various buildings were roaming around in the leadup to the attack, and that fire control systems in WTC7 had been shut down during the daylight period in the week leading up to the attack. Who knows- perhaps to install bombs, perhaps to interfere with the fire control system, perhaps unrelated.