Moral Realism (or Moral Objectivism) is the meta-ethical view (see the section on Ethics) that there exist such things as moral facts and moral values, and that these are objective and independent of our perception of them or our beliefs, feelings or other attitudes towards them. Therefore, moral judgments describe moral facts, which are as certain in their own way as mathematical facts.

It is a cognitivist view in that it holds that ethical sentences express valid propositions (and are therefore "truth-apt" i.e. they are able to be true or false), and that they describe the state of the real world. It contrasts with various types of Moral Anti-Realism, including non-cognitivist or expressivist theories of moral judgment, error theories, fictionalist theories and constructivist or relativist theories.

Moral Realism has the advantage of purportedly allowing the ordinary rules of logic to be applied straightforwardly to moral statements, (so that we can say, for example, that a moral belief is false or unjustified or contradictory in the same way we would about a factual belief). It also allows for the resolution of moral disagreements, because if two moral beliefs contradict one another, Moral Realism (unlike some other meta-ethical systems) says that they cannot both be right and so there should be some way of resolving the situation.

Critics have argued that, while Moral Realism may be able to explain how to resolve moral conflicts, it cannot explain how these conflicts arose in the first place. Others have argued Moral Realism posits a kind of "moral fact" which is non-material and unobservable (in the way as objective material facts are observable), and therefore not accessible to the scientific method.

Plato and (arguably) Immanuel Kant and Karl Marx were moral realists, as well as more contemporary philosophers such as G. E. Moore and Ayn Rand (1905 - 1982).

There are two main variants:

• Ethical Naturalism
  This doctrine holds that there are objective moral properties of which we have empirical knowledge, but that these properties are reducible to entirely non-ethical properties. It assumes cognitivism (the view that ethical sentences express propositions and can therefore be true or false), and that the meanings of these ethical sentences can be expressed as natural properties without the use of ethical terms.
• Ethical Non-Naturalism
  This doctrine (whose major apologist is G. E. Moore) holds that ethical statements express propositions (in that sense it is also cognitivist) that cannot be reduced to non-ethical statements (e.g. "goodness" is indefinable in that it cannot be defined in any other terms). Moore claimed that a naturalistic fallacy is committed by any attempt to prove a claim about ethics by appealing to a definition in terms of one or more natural properties (e.g. "good" cannot be defined interms of "pleasant", "more evolved", "desired", etc).
• Ethical Intuitionism is a variant of Ethical Non-Naturalism which claims that we sometimes have intuitive awareness of moral properties or of moral truths.