Partisan bias and hostility have increased substantially over the last few decades in the American electorate, and previous work shows that partisan strength and sorting help drive this trend. Drawing on insights from moral psychology, however, we posit that partisan moral convictions heighten affective polarization beyond the effects of partisanship, increasing partisan animosity and copartisan favoritism. Testing this theory using data from two national samples and novel measures of affective polarization in everyday life, we find that people who tend to moralize politics display more partisan bias, distance and hostility, irrespective of partisan strength. These results shed light on a different moral divide that separates the American public and raise key normative questions about moral conviction and electoral politics.
