||Moral philosophy has been divided traditionally into three categories. At the opposite ends of these categories are metaethics - the theoretical study of moral thought, language, and properties - and applied ethics - the attempt to use philosophical tools to provide practical ethical solutions to pressing moral problems. As a subject category, normative ethics lies between these two opposite ends of moral philosophy. Many philosophers in normative ethics investigate ethical theories the aim of which is to systematically describe what makes acts right and wrong. These theories include utilitarianism, consequentialism, Kantian theories, contractualism, contractarianism, virtue ethics, various pluralist views, natural law theory, and so on. Normative ethics also covers various other middle-level topics in moral philosophy such as the nature and commensurability of moral values, the justification of moral constraints and options, the existence of moral dilemmas; desert, natural rights, the Doctrine of Doing and Allowing and the Doctrine of Double Effect, the connection between evaluative notions such as goodness and deontic notions such as reasons, egoism and altruism, virtues and vices, promises and agreements and so on.