Nevermore, welcome to the forum, If I havent already said so.
I've been led to believe that 9-11 was the first time in history where two steel framed buildings completely collapsed after an initial, non-catastrophic impact by a plane and subsequent short duration fire.
Well given it is the first time that a jet airliner has crashed into a skyscraper (first that I know of), there is no precedent, so yes it is the first time for a number of things, including the collapse.
What is your frame of reference for calling the fires "short duration". I will assume until you correct me that you mean short compared to some other highrise fires that have lasted for hours and hours without the building collapsing...but in ALL of those cases, there was no impact damage, no severing of supportr columns, no removal of fireproofing.
You seem to approach this from a causality perspective. An aircraft crashes into a WTC building (cause X) leads to the building collapsing (effect Y). X must not be a "necessary" cause of Y since steel framed buildings have collapsed without a plane being involved. So X must be a "sufficient" cause of Y. However, if X is only a sufficent cause of Y then it seems logical that there could be other causes (Z) for collapse Y.
if your range is 0<possibility<infinity, than yes I suppose there are other "possible" causes, but given the evidence to date, the overwhelming MOST PROBABLE CAUSE is:
...the combination of Jet Airliner impact with subsequent severing of support columns, combined with removal of 60% or more of the spray on firep proofing via the impacts, and the multi-level (8-10 levels each) fires heated to much higher temps that that of the igniting jet fuel, via contents of the building burning, that together caused the collapse of the towers.
Or are you suggesting that the causal relationship here is rather an INUS condition ("insufficient and non-redundant parts of unnecessary but sufficient causes")? (note: see Wikipedia's entry for Causality).
ummm ya okie dokie...moving on.
If this is either a sufficient causality or an INUS condition I would think, given the assumption that this was the first instance where a plane impact and short duration fire caused the collapse of a steel frame structure, further digging for an explanation is justified.
5 years worth of your suggested "digging" has yielded jack squat in terms of legitimate evidence for any alternate theories. And I disagree, if we use your theory, than what about the possibility of "no-planes"? Should we waste tax dollars looking into that. Or how about some new alien technology?
Forget the "conspiracy theorists" for a second and consider how important understanding the cause of the collapse effects safe architectural design, emergency response, insurance coverage and building demolition. Should the professionals in these industries be satisfied with the simple causality you offer?
yes, because hundreds of qualified experts in the field looked at the evidence and came up with the MOST PROBABLE CAUSE for the collapses. Other theories, had they any legitimacy, I am sure would have been considered by these intelligent, patriotic individuals.
TAM