The greatest political support for taxing the rich emerges when compensatory arguments can be credibly applied in policy debates. This happens when it is clear that taxing the rich more heavily than the rest serves to correct or compensate for some other inequality in government action.
Taxing the Rich: A History of Fiscal Fairness in the United States and Europe
by Kenneth Scheve, David Stasavage
Chapter One: Why Might Governments Tax the Rich?