I'm not a proponent of an additional FTT, I personally think increasing it is a horrible idea. However I also do my best to be intellectually honest, and being intellectually honest in this debate means pointing out that:
1. We've had a transaction tax for nearly a 100 years.
2. Therefore is hyperbole the claim it will "exterminate US markets" as is claimed in this very thread. If you check out the other thread hundreds of posts long on an FTT, which has apparently been imminent for at least a decade, you'll see page after page of this type of hyperbole. So pointing out the hysterics around this discussion are exactly that is in no way an attempt to "delegitimize opposing arguments". In fact it's the opposite, an attempt to focus those opposing arguments on more valid points.