The purpose of the physical sciences is to predict the order in which events will succeed one another. Human behavior, also, can sometimes be successfully predicted. However, even successful predictions of human behavior do not provide an understanding of it, for understanding a human action requires knowing its goal, even though such knowledge of goals either cannot or need not be obtained in the case of nonhuman behavior. Which one of the following most accurately expresses the argument's conclusion? ['The methods used to predict human behavior must involve reference to the psychological states of human agents.', 'Successful predictions of human behavior do not constitute an understanding of that behavior.', 'In some cases, but not in others, understanding an event consists in the ability to predict the occurrence of that event.', 'The goal of the physical sciences is to predict the order in which events will occur.']