The purpose of this article consists in identification of the bases of a normativeness in modem ethics, object of studying in which is not practice, but moral knowledge. The modern moral philosophy developed from opposition between intellectualism where the Good was thought in categories "true" and "false", and sentimentalism for which there is no moral truth, but there are only moral emotions and feelings. Today this discussion is still actual, however it has got new sense in connection with criticism of ethical rationalism and realism in modern metaethics.