Inequality and Vertical Mobility over the very long run

The recent increase in inequality in the U.S. and other developed countries has stimulated debate among economists. This debate is best exemplified by Thomas Piketty’s Capital in the twenty-first century and his critics. Taking aside the predictions for the future and the role that capital gains play in this debate, a deeper question is: what is a “normal” level of inequality in historical terms? In other words, if we take the estimates at face value, and inequality today is similar to that of the 19th century and higher than most of the middle of the 20th century, which one is the historical anomaly? Is it normal to have high levels of inequality, and the 20th century was an exception, or is it normal to have low levels of inequality and the 19th century was an exception? Without information on inequality before the 19th century, it is hard to answer the above questions.