Abstract from Facundo Alvaredo et al’s paper “The Top 1 Percent in International and Historical Perspective” :
The top 1 percent income share has more than doubled in the United States over the last 30 years, drawing much public attention in recent years. While other English-speaking countries have also experienced sharp increases in the top 1 percent income share, many high-income countries such as Japan, France, or Germany have seen much less increase in top income shares. Hence, the explanation cannot rely solely on forces common to advanced countries, such as the impact of new technologies and globalization on the supply and demand for skills. Moreover, the explanations have to accommodate the falls in top income shares earlier in the twentieth century experienced in virtually all high-income countries. We highlight four main factors. The first is the impact of tax policy, which has varied over time and differs across countries. Top tax rates have moved in the opposite direction from top income shares. The effects of top rate cuts can operate in conjunction with other mechanisms. The second factor is a richer view of the labor market, where we contrast the standard supply-side model with one where pay is determined by bargaining and the reactions to top rate cuts may lead simply to a redistribution of surplus. Indeed, top rate cuts may lead managerial energies to be diverted to increasing their remuneration at the expense of enterprise growth and employment. The third factor is capital income. Overall, private wealth (relative to income) has followed a U-shaped path over time, particularly in Europe, where inherited wealth is, in Europe if not in the United States, making a return. The fourth, little investigated, element is the correlation between earned income and capital income, which has substantially increased in recent decades in the United States.
And here is Greg Mankiw’s abstract from his much discussed (and unjustly maligned) paper:
Imagine a society with perfect economic equality. Then, one day, this egalitarian utopia is disturbed by an entrepreneur with an idea for a new product. Think of the entrepreneur as Steve Jobs as he develops the iPod, J. K. Rowling as she writes her Harry Potter books, or Steven Spielberg as he directs his blockbuster movies. The new product makes the entrepreneur much richer than everyone else. How should the entrepreneurial disturbance in this formerly egalitarian outcome alter public policy? Should public policy remain the same, because the situation was initially acceptable and the entrepreneur improved it for everyone? Or should government policymakers deplore the resulting inequality and use their powers to tax and transfer to spread the gains more equally? In my view, this thought experiment captures, in an extreme and stylized way, what has happened to US society over the past several decades. Since the 1970s, average incomes have grown, but the growth has not been uniform across the income distribution. The incomes at the top, especially in the top 1 percent, have grown much faster than average. These high earners have made significant economic contributions, but they have also reaped large gains. The question for public policy is what, if anything, to do about it.