Or does it require hundreds of thousands of people on the inside?
For instance there are people who believe that 9/11 was possibly an inside job, but don't think the towers were demolished, so obviously for their conspiracy, it doesn't require all these planting eyewitnesses all over New York and Washington that you are on about does it?
And lets just assume for a minute that the buildings were demolished, then you are employing another logical fallacy that it would require an army of people.
Didn't you ever see what Timothy McVeigh did to the building in Oklahoma? He nearly totalled the entire building, imaging if he had a friend or two with him with trucks? They could have completely flattened that building which was like 8 stories, all in one morning.
So image what a few McVeighs could do the WTC if they had more experience, time and equipment?
Besides, I digress......
Put it simply, if you believe that no explosives were needed and the towers came down, then logically, only one explosives could have been planted and it would have still happened according to your logic, which kind of shoots down the whole, it requires tons of explosives and lots of men, with many days,weeks, months argument down in flames.