George Mason University economist Donald Boudreaux offers Barron’s readers a less-than-glowing review of Thomas Piketty’s book on capital and income inequality.

Thomas Piketty’s Capital in the Twenty-First Century might soon stand with Karl Marx’s Capital, which inspired its title, as one of the most influential economic masterworks of the past 150 years. But sad to say, this 696-page tome, ably translated by Arthur Goldhammer, is no more enlightening about capitalism in the 21st century than Marx’s Capital was about capitalism in the 19th century.

As a publishing phenomenon alone, the Paris School of Economics professor’s treatise, which has been hailed by three Nobel laureates—Paul Krugman, Joseph Stiglitz, and Robert Solow—commands our attention. It is also noteworthy as a symptom of a perverse ideology that seems to dominate progressive thinking, including that of President Barack Obama and President François Hollande of France, and of a flawed method of economic analysis.

Many of us care about whether, and to what extent, the broad masses of people have improved absolutely their material conditions of life. While Piketty (pronounced “PEEK-et-tee”) doesn’t entirely ignore that question, he focuses instead on the causes and cures of relative disparities in monetary income and wealth across groups of people and over centuries. Some ways of narrowing those disparities, such as punitive rates of taxation, might run the risk of dragging down everyone, rich and poor alike. But for Piketty, the importance of diminishing monetary inequalities is so monumental that he all but totally ignores such risks. …

… Flaws aplenty mar Piketty’s telling of the capitalist saga, flaws that spring mainly from his disregard for basic economic principles. None looms larger than his mistaken notion of wealth.

Every semester, I ask my freshman students how wealthy they would be if they each were worth financially as much as Bill Gates but were stranded with all those stocks, bonds, property titles, and bundles of cash alone on a desert island. They immediately see that what matters is not the amount of money they have but, rather, what that money can buy. No principle of economics is more essential than the realization that, ultimately, wealth isn’t money or financial assets but, rather, ready access to real goods and services.

Piketty seems barely aware of this reality, focusing on differences in people’s monetary portfolios. He therefore ignores the all-important supply side: what people—rich, middle class, and poor—can buy with their money. Yet, to the extent that inequalities are at all relevant, the only ones that really matter are inequalities in access to real goods and services for consumption. Bill Gates’ living quarters are larger and more elegant than mine and, I dare say, yours. But even the poorest people in market economies have seen their ability to consume skyrocket over time. And the poorer they once were, the greater has been the enhancement of their ability to consume.