Why Be Moral?

The dissertation mainly discusses an important question in ethics:Why should we do this action? The answer to this question runs through the whole history of the research of ethics. From the Linguistic Turn in twentieth century, the rise of meta-ethics is the most remarkable event. Their questions are different with other past ethics:Do moral properties, such as rightness and goodness, exist? What is the semantic function of moral statement? How can moral judgment motivate to act as a reason? With G. E. Moore’s famous open question argument, a moral property cannot be reduced to some natural properties. But this argument causes double misunderstanding, not only injure itself, but also contribute to the rebirth of naturalism. On the one hand, non-cognitivists, who inherited the open question argument’s refutation of naturalism, argue that the moral judgments only express non-cognitive state, such as emotions or desires. On the other hand, naturalists get a rebirth through the relation between moral property and natural property. These constitute the center moral discussion in the whole past century.Our point is intuitionism. This view suggests that rightness of an action is a moral fact, and moral judgment express a cognitive state, and can motivate to act as a reason. We adopt two ways to justify this view. First, we try to find the ground from different kinds of ethics to support it. Second, we criticize the non-cognitivists by Frege-Geach problem, and the naturalists by the relation of two kins of properties. The discussion of other standpoints is critical, while the discussion of intuitionism is exploratory.The main body of this dissertation is divided into five chapters. In the first chapter, we discuss three philosophers, Aristotle, Hume and Kant, and try to find a positive answer. The second chapter describes the intuitionism in Sigwick, Moore and Ross. Though different intuitionists have different point about the priority of rightness or goodness, they have agreements that moral property is a non-natural fact. The third chapter discusses Ayer’s refutation of descriptivism. The validity of practical reason which challenges to the non-cognitivists is the account that the moral judgments express some non-cognitive state, incapacitation of being true or false. Following sections discuss the other kind of non-cognitivists’ solution to this problem, but they all failed. In the fourth chapter, we discuss two kinds of naturalism. The non-reductionism claims that moral properties are supervene upon natural properties. The reductionism holds that moral properties are reducible to natural properties, and the definition turns out to be empirically justifiable. In chapter five, from three different perspectives, we discussed the view of internalism, realism and coginitism.