Chapter four introduces many terms and concepts related to interests. Altruism means concern for the well-being of others, and egoism means concern for one’s own self-interest. The chapter is further subdivided into the following sub-sections:Psychological Egoism: This section offers a definition of psychological egoism: “psychological egoism is a descriptive theory about what people are like” (p. 70) and it says that people basically act with their own self-interest in mind. There are two keyinterpretations here. On one interpretation, it says that people are basically selfish. On the other interpretation, it says that people may act with long term self-interests in mind, so immediate selfish drives are not necessarily a factor. The section develops other interpretations, and it closes with some comments about how hard it would be toprove that the theory is true. How do we assess motivations for actions when people are often not sure of their own motivations?