Lower top rate and gain more revenue?

You cannot get a clear test on tax policy to determine the revenue gain from a change in rates unless you can control or isolate other factors. This is what makes economics so difficult and this is what makes economics different from other hard sciences which allow for experimentation. Nevertheless, the following graph has to be considered when discussing policy. The tax cut occurred at the highest marginal level and revenues actually increased. If the policy of raising rates is to get more revenue, the conclusion may be flawed.