D’Erasmo, Mendoza, and Zhang have a new NBER working paper on this question. It is the most serious and scientific approach to American debt sustainability I have seen, ever. Here are two key sentences:
The dynamic Laffer curves for these taxes [capital taxes in the U.S., labor taxes in Europe] peak below the level required to make the higher post-2008 debts sustainable.
The results of the applications of the empirical and structural approaches paint a bleak picture of the prospects for fiscal adjustment in advanced economies to restore fiscal solvency and make the post-2008 surge in public debt ratios sustainable.
One point the authors emphasize is that, unlike after earlier episodes of American debt binges, America today has not reestablished a comparable primary surplus. The authors suggest taxes on labor or consumption can restore fiscal solvency, but higher taxes on capital won’t work, given dynamic and Laffer curve considerations. They do not devote comparable attention to changes in the trajectory of government spending.
It is wrong to call this “science” outright, but it is the closest to science we have on these questions. There is a possibly different ungated copy here (pdf).
And along related lines, consider this new Brookings study of boosting the top tax rate to fifty percent, by Gale, Kearney, and Orszag:
We calculate the resulting change in income inequality assuming an explicit redistribution of all new revenue to households in the bottom 20 percent of the income distribution. The resulting effects on overall income inequality are exceedingly modest.
You will not hear everyone shouting that one from the rooftops. And of course it does not all get redistributed to the bottom twenty percent, believe it or not.