Primitive tribes must be the most equal of societies. Few of us, though, aspire to that kind of equality.

The thought occurred on reading about (note, not reading) Thomas Piketty's Capital in the 21st century that seems set to be the best-selling economics text of recent times. Piketty, who has in some quarters been hailed as a latter-day Marx, notes that income inequality in the US remained stable from 1910 to 1920, rose from 1920 to 1929, fell steeply after the Great Crash of October 1929 until the end of the war, remained stable until around 1980, and then rose steadily again, until in 2007 it rose above the level of 1928. A graph can be seen on Piketty's web site. To set right what he sees as a dire situation, possibly to prevent a capture of western governments by its poverty-stricken masses, Piketty suggests a general wealth tax and a top income tax rate of 80%.

Piketty seems to think that greater equality is something much to be desired. To test this I searched on the net for inequality measures for the Soviet Union to compare with the US. And I found some interesting figures in a paper Income Distribution in the USSR in the 1980s by Michael V. Alexeev and Clifford G. Gaddy. For the US some comparable figures can be found on the Federal Reserve Bank of St Louis web site.

The table below compares the two:

Gini Coefficients for the USSR and the US

Year	USSR	USA
1980	0.290	0.403
1985	0.284	0.419
1988	0.290	0.426
1989	0.275	0.431
1990	0.281	0.428

Readers may recall that the only revolution that happened was in the USSR, not in the US.

Poring over English factory inspector reports in the sixties and seventies of the 19th century Marx reached the conclusion that the overthrow of capitalism was imminent. If nothing else, Marx's prognostications should serve as a warning that one must not use short-term data to jump to eternal conclusions. In the graph the current trend of rising inequality dates from around 1980. Is there any other variable that could explain this as well as the shifts in inequality mentioned earlier: stable from 1910 to 1920, a rise from 1920 to 1929, a fall thereafter until 1945, stable until 1980, and a rise thereafter?

It is illuminating to look at the following graph of US long term interest rates.

It is taken from The real rate of interest from 1800-1990: A study of the US and UK by Jeremy J. Siegel. The graph of inequality on Piketty's site and the interest rate graph here follow a similar trajectory. The period from 1910 to 1920 is a period of rising rates and stable inequality. Thereafter the interest rate falls and inequality grows. Similarly the period from 1980 is a period of rising inequality, and interest rates begin to fall from around that date. The Depression years were an exception. So were the war years but then that was a period of wage and price controls.

One cannot help but feel that low interest rates help push up asset prices and thus boost those who earn a substantial part of their income from financial assets. Now it so happens that the people who complain about rising inequality, Paul Krugman to take one example, are also the ones clamouring loudest for keeping interest rates low. Talk about the law of unintended consequences.