Correlation and Causation and Inequality

In a takedown of the recent S&P study on inequality and growth (HT: MR), John Cochrane gives us the following quip that I wanted to share/save:

Well, that's what forecasting is about. "The weather forecaster causes rain" is a model that forecasts well. Until you try to kidnap the forecaster and make a sunny day.

It sounds like the plot of a very fun movie.

With regards to the S&P report on inequality, worries about inequality impacting aggregate demand shouldn't be too worrisome. Aggregate demand is a cyclical issue that can be managed by monetary policy when needed. 

However, the hypothesis that relatively bad education outcomes are driving both low growth and higher inequality than in the past is more worrisome. The modern education system is ill suited to the needs of many people and those at the bottom of the ladder are increasingly forced to compete on a global basis when they enter the workforce (Or rather, they are forced into local service jobs because of potential global competition). Combined with assortive mating, the children of those with poor education may continue to have poor education and low productivity themselves - thus lowering future economic growth.

It should be pointed out that inequality is not the causal drver of growth in this analysis, education and globalization are the main driving factors. And while this is related to inequality, worrying about the education gap is different from worrying about whether or not the growing wealth of the 1% will impact future economic growth.

Here is a thesis of how inequality of the 1% and growth might be related (particuarly in more corrupt developing countries): High levels of inequality are sometimes a symptom of excessive rent seeking. This rent seeking is damaging to long term economic growth. In these cases redistribution may not improve growth outcomes unless the rent seeking behavior is itself taxed. Since the most successful rent seekers are generally people with significant political influence, it's very unlikely that they'd lose the battle. But it could still be one worth having.