Atif Mian and Amir Sufi:
Why the Income Distribution Matters for Macroeconomics, by Atif Mian and Amir Sufi: A central argument we have made on this blog and in our book is that the distribution of income/wealth matters a great deal for thinking about the macro-economy. Convincing some of this fact is not easy...
Perhaps the easiest way to see the importance of the income distribution is to examine how households respond to a windfall of cash or wealth. Do they spend the money, or do they save it? And does the spending response to a windfall of cash depend on the income of the household?
The answer is a resounding yes: low income households spend a much higher fraction of cash windfalls than high income households. In the parlance of economics, low income households have a much higher marginal propensity to consume, or MPC, than high income households.
This is one of the most well-established facts in empirical research in macroeconomics. Here is a summary: ...[reviews evidence]...
The implications of the differences in spending propensities across the population are enormous, especially if we believe that inadequate demand explains economic weakness during severe recessions. For example, facilitating debt forgiveness or progressive fiscal stimulus rebates will likely boost spending during the most severe part of a recession.
But perhaps even more interesting are the implications for the secular stagnation hypothesis, which holds that we are in a long-run stagnating economy because of inadequate demand. Is it a coincidence that the secular stagnation hypothesis is being revived exactly when income inequality is accelerating? If a higher share of income goes to the wealthiest households who spend very little of it, then perhaps these two trends are closely related.