Does intelligence have a U-shaped relationship with leftism?

• Solon (2014) makes an interesting and thoughtful contribution.
• He concludes that intelligence has a U-shaped relationship with leftism.
• I propose a number of qualifications to his conclusion.

Solon (2014) makes an interesting and thoughtful contribution to the literature on intelligence and political beliefs. He concludes that there is a U-shaped relationship between intelligence and leftism such that people with very low and very high intelligence tend to be more left-wing. One piece of evidence he cites is the prevalence of support for the Democratic Party among scholarly elites in the United States. Here I propose a number of qualifications to Solon's (2014) conclusion. I begin by noting that Solon (2014) employs quite a specific definition of ‘left’, which does not reflect how the term is often used in political discourse. I then analyse the functional form of the relationship between verbal intelligence and 23 separate measures of political beliefs from the U.S. General Social Survey. Some of the results support Solon's (2014) thesis, while others do not. I also review previous studies that have found evidence contradicting Solon's (2014) thesis. Finally, I outline several reasons why the prevalence of support for the Democratic Party among scholarly elites does not constitute overly compelling evidence that there is a U-shaped relationship between intelligence and leftism.