“What I’m really interested in is called social ethics,” Welch explains. What a society counts as moral or immoral is subject to the particular zeitgeist—the spirit of the times. For example, at the time of the slave trade, “most people who were slave owners thought it was moral. Even a few blacks, once they were freed, had slaves.” As a social ethicist, Welch has been trying to understand not just the way individuals make moral choices but how a whole society begins to decide “what counts as moral.”