Since the early 2000s, research by Thomas Piketty and Emmanuel Saez (and
their coauthors, including Anthony Atkinson and Gabriel Zucman) has revolutionized
our understanding of income and wealth inequality. The crucial point
of departure for this revolution is the extensive data they have used, based largely on
administrative tax records. Piketty’s (2014) Capital in the Twenty-First Century is the
latest contribution in this line of work, especially with the new data it provides on
capital and wealth. Piketty also proposes a framework for describing the underlying
forces that affect inequality and wealth, and unlikely as it seems, a bit of algebra that
plays an important role in Piketty’s book has even been seen on T-shirts: r > g