Yes. The evidence is in the state of our economy. When people, especially the wealthy, have less of their money to invest, then they won't invest it - in building and maintaining businesses, in hiring and keeping employees, in funding research, etc.
Don't get me wrong, taxes aren't solely responsible for our wretchedness, but they are a very large factor, and a simple one to remedy. Our government, if it wants to keep running as planned, must, must, must cut spending in mountain-moving ways and then cut taxes.
Have a look at
history:
The economic situation in 1920 was grim. By that year unemployment had jumped from 4 percent to nearly 12 percent, and GNP declined 17 percent. No wonder, then, that Secretary of Commerce Herbert Hoover — falsely characterized as a supporter of laissez-faire economics — urged President Harding to consider an array of interventions to turn the economy around. Hoover was ignored.
Instead of "fiscal stimulus," Harding cut the government's budget nearly in half between 1920 and 1922. The rest of Harding's approach was equally laissez-faire. Tax rates were slashed for all income groups. The national debt was reduced by one-third.
The Federal Reserve's activity, moreover, was hardly noticeable. As one economic historian puts it, "Despite the severity of the contraction, the Fed did not move to use its powers to turn the money supply around and fight the contraction." By the late summer of 1921, signs of recovery were already visible. The following year, unemployment was back down to 6.7 percent and it was only 2.4 percent by 1923.
What's even more interesting is that this article goes on to tell about a parallel depression in Japan, the outcome of which was very different.