[CCIP]

I think you're right in that in some sense, it's always a matter of belief - there's probably noone out there who has actually seen all the evidence and has the expertise to interpret it on their own, meaning that anyone's views of it boil down to a) who they trust as credible sources of analysis; and b) common sense (which is itself 'sourced' from somewhere). The amount of evidence anyone has on their hands, however, is in that case not relevant if they only have a narrow view on interpreting it.

But here's where I'm with Steve and where I think the Achilles' heel of conspiracy theories lies: in order to pull something so complex off and cover it up, you have to push the data through a very narrow interpretation channel. And that interpretation channel has to take as granted some very unlikely and un-common-sense things, along with the notion that what we know about the workings of public officials is a complete lie. No matter how much data you have, you still have to force it into a convoluted sort of puzzle. Sheer probability and breadth of perspective tends to defeat this most of the time. In the real world, the convoluted version is very rarely the right one. The narrow version tends to ignore broader interpretations and realities of how information travels these days.

Sadly, the fact that 9/11 itself was such a bizzare and incompetently-handled event easily lends itself to these things.