James commented that the Popular Mechanics book does a thorough job of debunking the 9/11 conspiracy theories. It doesn't, and David Ray Griffin does a very thorough debunking job on the Popular Mechanics book. I said this to James in the comments, which is worth bringing up front:
"If you don't know then you obviously haven't read it. I have read it and it's crap. The site that I linked to does a much more coherent and thorough job in debunking the conspiracy theories, can I suggest you read that and become a little better informed?
I could easily be wrong about this - particularly the second as I'm not a physicist or civil engineer - but the pathetic level of argumentation put out by the Popular Mechanics book, mindlessly parroted by other ignoramuses, only encourages the speculation. The best thing about the site that I linked to is that it takes the conspiracy arguments seriously and takes the time to show why they are wrong - and I accept that most of them are wrong."
In particular, after posting what I wrote yesterday, I watched this video at that site, which I think is very good, and, with the accompanying analysis, goes a long way to answer one of my core concerns about 'the gravity of the question':
I remain sceptical about my scepticism because this whole issue provokes a lot of cognitive dissonance in me, and as I've said before I'd be tremendously grateful to be relieved of it.