On January 1, 2014, the top federal income tax bracket in the United States went from 35 percent to 39.6 percent.
Many republicans claimed that lowering the rewards for working (the net after-tax wage rate) would lead to less work effort and a lower labor supply. Proponents of the tax increase replied  that this claim was baseless because it “ignored the income effect of the tax increase (net wage decrease).” Explain what these critics meant.