What is t*?
Thomas Sowell says that when tax rates are raised on high-income individuals, they respond to incentives by arranging their financial affairs differently to minimize those taxes.
Folks, like blogger Megan McArdle, lecture/patronize opponents of tax increases that current marginal tax rates are not near the bend in the Laffer Curve (the point where increasing tax rates would reduce revenue).
This is from Mark Perry’s blog, Carpe Diem:
The U.K. government is learning about the economic lesson that “if you tax something, you get less of it.” Following an increase in the top marginal income tax rate to 50%, tax revenues from high-income taxpayers are falling, and are not going up, as the Treasury somehow expected by ignoring the economic lesson that “people respond to incentives.” A U.K. Treasury official explained the disappointing drop in tax revenues by saying it “was partly due to highly-paid individuals arranging their affairs to avoid paying the 50% rate.” Duh.
Our Dinner Table 
People can legitimately argue that we may be on one side of the curve or the other. But I don’t see how anyone can argue that the curve doesn’t exist. But I see it all the time. 😉