Well, I think it's obvious that the best evidence for 9/11 CT's is that the freaking buildings collapsed!
The one truther I've ever seen in real life opened the subject in our conversation with this gem: "You know, buildings don't commit suicide." (The preceding conversation between us had been on the subject of the choices of fish available in the sushi bar we were in, so this was a rather abrupt change of subject.)
And he's right! I've been in many many buildings, large and small, and not one of them has exhibited the slightest trace of self-destructive ideation. (Which is a good thing, because
giving them lithium would apparently be counterproductive).
Buildings in the Western world are so well engineered, constructed, and inspected that we all take their durability for granted. Whatever hesitance our grandparents might have felt about walking into some grand atrium overhung by soaring tiers of seemingly unsupported balconies or crossing a fragile-looking span over a fatal abyss has long vanished. Only
once in a great while does our trust in the structural soundness of our urban environments prove to be mistaken.
So, seeing the collapses on 9/11, seeing other disasters in which large buildings did not collapse, and thinking (either at the time, or in retrospect) that the wtc buildings "must have been" demolished is understandable. Not stupid, not silly, and not (unless the individual is in a position where he or she should already know better) ignorant. It only becomes a stupid, silly, and ignorant belief when the better explanations of the event, better supported by evidence -- offered by the same sources of engineering, construction, and building inspection expertise that they trust to make buildings stay standing in the first place -- are ignored or disregarded.
Respectfully,
Myriad