In 1938, the economic sociologist Robert Merton lamented that, while many writers had touched upon the problem of unintended consequences, no one had oﬀered a systematic treatment of them. Eighty years later, Merton’s observation still holds true. Philosophers and theologians discuss chance and fate, but say almost nothing about the unintended consequences of human actions, policies, and laws. This oversight is understandable, given that most professors have little hands-on experience formulating and executing wide-reaching policies, devising products, or operating in markets. Uninvolved with actual consequences of choices, moralists and political theorists have largely neglected this vital subject. Theologians have dealt with unanticipated eﬀects by attributing them to the unfathomable will of God and thus have avoided analyzing either the causes of these eﬀects or the challenges they pose for moral evaluation and planning.