??? The 16th amendment changed that. A natinal consumption tax is something that would cause everyone to have skin in the game and is by no means a bad thing. Cain may not be a George Washington (or is he?), but I certasinly don't believe he is one of the progressives who is out to destroy liberty and unite us under a one world governance. He spent YEARS as a talk radio host where he was free to spew wahtever he pleased without regard to how people would judge him and he spoke in terms of American exceptionalism and often times promoted libertarian ideas (one of his staunchest backers was Neal Boortz, a natioanlly syndicated libertarian host).
If you have the time and inclination there are some superb treatises questioning the constitutionality of the 16th Ammendment. If you dig deeply enough and read the reference material you may come to see it as I do. No guarantees but I have come to the conclusion that those "old dead white guys" were a lot smarter than we give them credit for. Just sayin'.
Ask him about the Federal Reserve System...