The second of the four parts of the book concerns human nature. First, Singer investigates the psychological reasons why human beings don’t give more in foreign aid.

Singer first examines the human proclivity for self-interested behavior. He describes a psychological experiment with two test subjects and two tasks. One task is labeled interesting and engaging; the other is supposedly boring. Most subjects agree that the moral course of action is to flip a coin in order to determine which subject performs which task. However, when given the choice, many people either don’t flip the coin or lie about the results so as to receive the more pleasant, engaging assignment. Despite this clearly self-interested result, Singer notes that people do plenty of altruistic things of no obvious benefit to themselves. Singer writes that there are psychological factors at stake that self-interest cannot explain away.

Singer writes that other experiments show people respond with strong altruistic emotions when there is an identifiable victim. People are more likely to give if they know they can change the life of a single person with a distinct identity—a phenomenon known as the “identifiable victim effect.” They donate less to causes in which there are large numbers of unidentified persons in need, even if the need is more substantial: “[T]he subjects of the experiment reported feeling stronger emotions when told about one child than when told about two” (47).