Capital in the 21st Century

Thomas Piketty’s landmark 2013 work on wealth and income inequality across modern economies. The core thesis is expressed as r > g: when the rate of return on capital (historically 4–5% per year) exceeds the economy’s growth rate (historically 1–1.5% per year), inherited wealth grows faster than wage income, and inequality compounds over generations.

Key arguments from Erik Torenberg’s notes:

• Rentiers vs. laborers. Laborers live paycheck to paycheck; their income grows roughly with GDP per capita. Rentiers (those living off capital returns) grow at the rate of return on capital — structurally higher than wage growth in most peacetime periods.
• Wars reset the clock. The 1914–1945 period was exceptional: hyperinflation, asset destruction, wartime taxes, and capital controls compressed inequality. The “great compression” of the mid-20th century was the exception, not the baseline.
• The American Dream’s structural basis. America historically had less accumulated rentier wealth than Europe, because it had existed as a sovereign nation for a shorter time. Less generational accumulation meant more room for meritocratic mobility — which weakens as the rentier class compounds.
• The “super-laborer” phenomenon. The rise of the top 0.1% is partly driven by executives and founders who earn both from labor (high salaries) and capital (equity stakes) — fewer “rich bums,” more “rich earners.”
• Piketty’s prescription: a global wealth tax. Alternative diagnostics point to housing supply (housing transfers wealth from laborers to rentiers through rent), college debt, and mechanisms to give laborers equity participation in growth.

Piketty’s r > g formula is the most widely-cited single result in economic inequality research in the past decade.

Where this appears

• Book Notes From Thomas Piketty’s… (tweet)