Income shares, secular stagnation and the long-run distribution of wealth

Four alarming stylized facts have recently emerged in the United States: (a) a decline in the labor share of income; (b) a decline in labor productivity; (c) an increase in the top 1% wealth share and (d) an increase in the capital-income ratio. In Capital in the XXI Century, Thomas Piketty's argument is that the r > g inequality determines an increase in the capital-income ratio; if the elasticity of substitution in production is above one, the profit share rises. We provide a contrasting explanation that draws from the Post Keynesian approach to differential saving propensities between classes and the Classical-Marxian theory of induced technical change. In a simple model of "capitalists" and "workers," we show that institutional changes that lower the labor share-declining unionization, increasing monopsony power in the labor market, the global 'race to the bottom' in unit labor costs or the exhaustion of path-breaking scientific discoveries-can reduce labor productivity growth because of the lessened incentives to innovate to save on labor costs. A falling labor share reduces workers' total savings, and wealth concentrates in the capitalists' hands. A higher profit share and wealth share both put pressure on accumulation: but the long-run growth rate, which is anchored to labor productivity growth, has fallen. To restore balanced growth, the capital-income ratio must rise, independent of the elasticity of substitution. These tendencies are not inevitable: taxation can be used to implement any wealth distribution targeted by policymakers, while worker-crushing institutional arrangements can also in principle be reversed through policy. Neither change appears likely given the current institutional and global policy climate.