He identified three factors: Protestants tend to work a few more hours per week than Catholics. Protestants are more likely than Catholics to be self-employed. Protestant women are more likely than Catholic women to work full-time. It appears that Jörg Spenkuch found living proof of the Protestant work ethic. That was the theory put forth in the early 1900s by the German sociologist Max Weber, which argued that capitalism took off in Europe in part because Protestants embraced the earthly notion of hard work as part of their divine mission.
