Almost 50% of the population pay 0 tax, how is lowering taxes on the lower brackets going stimulate anything?
Same hogwash, different day. 50% of the population pays no federal income tax, but they still pay a lot of other taxes. For extremely high earners, those other taxes shrink to insignificance, because they spend only a small % of income on lifestyle, no matter how lavish.
Total taxes are a lot flatter than you think, actually regressive at the top-
http://www.ctj.org/pdf/taxday2011.pdf
Raising taxes on people who aren't spending their incomes but rather saving them will have little to no effect of the economy. Why do you think interest rates are so low, anyway? It's because we have a savings glut in a liquidity trap... the private sector is deleveraging tremendously, particularly the wealthiest.