Mark Thoma has the best data post so far on the execrable Romney speech, linking to the Hamilton Project work on taxes. This work makes a crucial point: even aside from the fact that there are other taxes besides the income tax, even aside from the larger point that lower-income working Americans are hardly grifters, the fact is that the vast majority of Americans do pay income taxes at some point in their life:

Thanks to the child tax credit and Earned Income Tax Credit, a fair number of working families with young children pay no income tax; thanks to the exemption on Social Security, many older Americans pay no income tax. But in middle age, close to 80 percent of the population pays income taxes, and even more, of course, pay federal taxes of some kind.

So the notion that almost half of our citizens are grifters isn’t just vile; it’s also based on a complete misunderstanding of tax realities.