Metaethics is the branch of philosophy that studies the nature of moral properties and moral judgments.

Emotivism is a moral theory that emphasizes the role of emotions in moral decision-making.

According to Emotivism, moral judgments express emotions.

A.J. Ayer is the most prominent philosopher associated with Emotivism.

Moral Objectivism is the belief that moral judgments are objective and independent of personal feelings.

Deontology is a moral theory that emphasizes the importance of following moral rules and duties.

Immanuel Kant is the most prominent philosopher associated with Deontology.

Consequentialism is the belief that the rightness or wrongness of an action is determined by its consequences.

Virtue Ethics is a moral theory that emphasizes the importance of developing good character traits.

Aristotle is the most prominent philosopher associated with Virtue Ethics.

Moral Relativism is the belief that moral judgments are relative to the culture or society in which they are made.

Existentialism is a moral theory that emphasizes the importance of individual freedom and choice.

Jean-Paul Sartre is the most prominent philosopher associated with Existentialism.

Moral Nihilism is the belief that there are no objective moral values or duties.

Kantianism is a moral theory that emphasizes the importance of following universal moral principles.