Myths of Rich and Poor authors W. Michael Cox and Richard Alm take on income-based measures of inequality here. Here's Don Boudreaux. Greg Mankiw offers a useful excerpt. Critics tend to point to trends in income shares as a proof of the "injustice" of the market economy--note the popular slogan "the rich get richer while the poor get poorer"--but there's a larger point that must be recognized. Channeling my inner Thomas Sowell, people don't buy food, clothing, and shelter with percentage shares. They buy them with real income. And, as Russell Roberts points out, that has been increasing, too.