The negative income tax proposed by Milton Friedman represents one of the fundamental ideas of modern welfare policy. However, the academic literature has raised two difficulties with it, one challenging its purported work incentives and the other suggesting the possible superiority of work...

The inequality of earnings and of family incomes in the United States has increased since the late 1970s. The large rise in earnings inequality between the 1970s and the 1990s could reflect either a rise in disparity of permanent incomes, a rise in earnings instability, or some portion of both....