For many liberals, diversity has become an unquestioned good—like justice, freedom, and happiness, the more diversity, the better. My research on morality, however, spurred me to question it. Given how easy it is to divide people into hostile groups based on trivial differences,36 I wondered whether celebrating diversity might also encourage division, whereas celebrating commonality would help people form cohesive groups and communities. I quickly realized that there are two main kinds of diversity—demographic and moral.
