“The rich are getting richer and the poor are getting poorer.” Senator Bernie Sanders first said those words in 1974 and has been repeating them ever since. Senator Sanders is not alone in his belief. Three out of four Americans agree with the statement, “Today it’s really true that the rich just get richer while the poor get poorer.”

Senator Sanders is half right: the rich are getting richer. However, his assertion that the poor are becoming poorer is incorrect. The poor are becoming richer as well.

Economist Gary Burtless of the Brookings Institute showed that between 1979 and 2010, the real (inflation-adjusted) after-tax income of the top 1% of U.S. income-earners grew by an impressive 202%. He also showed that the real after-tax income of the bottom fifth of income-earners grew by 49%. All groups made real income gains. While the rich are making gains at a faster pace, both the rich and the poor are in fact becoming richer.

In addition to these measurable real income gains, decreases in prices have given the poor increased purchasing power, helping to raise living standards for the worst off in society. As a result of falling prices such as for groceries and material goods, along with gains in real income, Americans have more income left after basic expenses.

Technology has also become cheaper, improving our lives in unexpected ways. For example, consider the spread of cell phones. There was a time when only the wealthiest Americans could afford one. Today, over 98% of Americans have a cellular subscription, and the rise of smart phones has made these devices more useful than ever.

Unfortunately, progress has been uneven. In those areas of the economy where competition is hobbled, such as education, housing, and healthcare, prices continue to increase.

Still, the percentage of the population classified as living in relative poverty has decreased over time. Why then do three quarters of Americans, including Senator Sanders, believe that the poor are “getting poorer?”

A simple logical error underlies Sanders’ belief. If we assume that wealth is a fixed pie, then the more slices the rich get, the fewer are left over for the poor. In other words, people can only better themselves at the expense of others. In the world of the fixed pie, if we observe the rich becoming richer, then it must be because other people are becoming poorer. Fortunately, in the real world, the pie is not fixed. U.S. GDP is growing, and it’s growing faster than the population.

Poverty remains a pressing issue, but Senator Sanders is incorrect when he says that the poor are becoming poorer. In the words of HumanProgress.org advisory board member Professor Deirdre McCloskey,

The rich got richer, true. But millions more have gas heating, cars, smallpox vaccinations, indoor plumbing, cheap travel, rights for women, lower child mortality, adequate nutrition, taller bodies, doubled life expectancy, schooling for their kids, newspapers, a vote, a shot at university, and respect.