And wealth is much more unequally distributed than income, so while a division of society into those who own things and those who work for a living is overly simplistic it's not totally off-base. All the shares of stock and houses and cash assets that people own constitute capital, or wealth. But Piketty uses an expansive definition of capital so that it is the same as wealth. There are different concepts of capital floating around in the economics literature. Piketty argues that this is how the economy of early 20th century Europe worked, that the tyranny of inherited wealth was destroyed only by the devastation of two world wars, and that in the 21st Century the United States and Canada will suffer from the same affliction. The provocative argument of Capital in the 21st Century is that market capitalism, including the kind of welfare state capitalism practiced in continental Europe, will eventually lead to an economy dominated by those lucky enough to be born into a position of inherited wealth. What does Capital in the 21st Century argue? In his new book, Piketty largely leaves that research agenda behind in favor of an inquiry focused on wealth inequality.

The vast majority of the contemporary debate on inequality is focused on the agenda set by that work. The duo was the first to carefully exploit American income tax data to show how highly concentrated income was in the hands not just of the top 10 or 20 percent of households but the top 1, 0.1, or even 0.01 percent. Thomas Piketty is a French economist who rose to prominence over the past decade thanks to his collaborations with Emmanuel Saez on income inequality.

The best solution would be a globally coordinated effort to tax wealth.

If it continues, the future will look like the 19th century, where economic elites have predominantly inherited their wealth rather than working for it.

Absent extraordinary interventions, we should expect that trend to continue.

The ratio of wealth to income is rising in all developed countries.

Can you give me Piketty's argument in four bullet points? But if you just want the bottom line, we have you covered. The good news is that there's no advanced math, and anyone who puts in the time can read the book. It's also 696 pages long, translated from French, filled with methodological asides and in-depth looks at unique data, packed with allusions to 19th century novels, and generally a bit of a slog. Thomas Piketty's Capital in the 21st Century is the most important economics book of the year, if not the decade.

Matt yglesias book