Ethical subjectivism (also known as moral subjectivism and moral non-objectivism)[1] is the meta-ethical view which claims that:
This makes ethical subjectivism a form of cognitivism (because ethical statements are the types of things that can be true or false).[4] Ethical subjectivism stands in opposition to moral realism, which claims that moral propositions refer to objective facts, independent of human opinion;[5] to error theory, which denies that any moral propositions are true in any sense; and to non-cognitivism, which denies that moral sentences express propositions at all.[6]
Non-objectivism (as it will be called here) allows that moral facts exist but holds that they are, in some manner to be specified, constituted by mental activity...The present discussion uses the label "non-objectivism" instead of the simple "subjectivism" since there is an entrenched usage in metaethics for using the latter to denote the thesis that in making a moral judgment one is reporting (as opposed to expressing) one's own mental attitudes (e.g., "Stealing is wrong" means "I disapprove of stealing").
[Objectivism and subjectivism] have been used more vaguely, confusedly, and in more different senses than the others we are considering. We suggest as a convenient usage, however, that a theory be called subjectivist if and only if, according to it, any ethical assertion implies that somebody does, or somebody of a certain sort under certain conditions would, take some specified attitude toward something.
A subjectivist ethical theorist is a theory according to which moral judgements about men or their actions are judgements about the way people react to these men and actions - that is, the way they think or feel about them.
Cognitivism is the denial of non-cognitivism. Thus it holds that moral statements do express beliefs and that they are apt for truth and falsity. But cognitivism need not be a species of realism since a cognitivist can be an error theorist and think all moral statements false.
As a first approximation, then, moral anti-realism can be identified as the disjunction of three theses: i) moral noncognivitism ii) moral error theory iii) moral non-objectivism.