Critics of market societies have denounced the corrosive social effects of unchecked capitalism for as long as pro-market ideologues have defended the system against such charges. But a new study offers that rare thing in the social sciences: a natural experiment to measure the correlation between capitalist development and social degradation. The results amply vindicate market-society critics.

In social science, there are few, if any, controlled experiments. Unlike natural scientists, social scientists can’t set up controlled environments in their laboratories and test things to their heart’s content. Still, it is possible—if rare and exceedingly difficult—to find perfect “natural experiments” in social science, when historical conditions align in such a way that the phenomenon to be studied is unleashed on a society in a clear and obvious way.

To examine the effects of rapid capitalist economic development, one country offers such a compelling natural experiment: my native Ireland. Until the 1990s, Ireland was an economic laggard. It was nowhere near as wealthy as its neighbor, Britain. At the same time, it maintained a very cohesive culture, with the Catholic faith at its center. In 1973, for example, more than 90 percent of Irish adults attended church services weekly.