This document discusses psychological egoism and various philosophers' perspectives on human behavior and motivation. It summarizes the key points of psychological egoism as the view that all human actions are ultimately motivated by self-interest. It then outlines Thomas Hobbes' and Epicurus' views that behavior is motivated by seeking pleasure and avoiding pain. Finally, it presents James Rachels' arguments against psychological egoism, including that people sometimes act against their desires, unselfish acts are defined by their object which is helping others, and unselfish people derive satisfaction from helping others rather than themselves.