For all the brain power thrown at the problem since then, however, specific evidence about inequality’s effects has been hard to find. Mr. Jencks said he could already picture the book’s reviews, “Professor Doesn’t Know What He Is Talking About.”…
One problem with these analyses is that they are based on correlations between levels of inequality and variables like life expectancy or the odds of poor children climbing the income ladder. But such correlations can’t prove inequality causes other social ills. They can’t disentangle inequality from the myriad things pushing American society this way and that.
Life expectancy in the United States might lag that of other countries because the United States still does not have universal health care. Scandinavia may enjoy higher upward mobility than the United States because governments in Sweden, Denmark and other Scandinavian countries invest a lot in early childhood education and the United States does not.
Lane Kenworthy, a sociologist at the University of Arizona, is all too aware of these limitations. He was to be Mr. Jencks’s co-author on the book about inequality’s consequences. Now he is going it alone, hoping to publish “Should We Worry About Inequality?” next year.
“People that worry about inequality for normative reasons have been very quick to jump on plausible hypothesis and a little bit of evidence to make sweeping conclusions about its consequences,” Professor Kenworthy told me.
It sounds like these sociologists are asking for some more methodological rigor in studying how inequality affects social life. Finding direct relationships between social forces and outcomes can be difficult but I look forward to seeing more work on the subject.
Read more in this follow-up interview with Lane Kenworthy.