Ethical subjectivism is the meta-ethical view which claims that:
This makes ethical subjectivism a form of cognitivism. Ethical subjectivism stands in opposition to moral realism, which claims that moral propositions refer to objective facts, independent of human opinion; 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.
The most common forms of ethical subjectivism are also forms of moral relativism, with moral standards held to be relative to each culture or society (c.f. cultural relativism), or even to every individual. The latter view, as put forward by Protagoras, holds that there are as many distinct scales of good and evil as there are subjects in the world. However, there are also universalist forms of subjectivism such as ideal observer theory (which claims that moral propositions are about what attitudes a hypothetical ideal observer would hold). Although divine command theory is considered by some to be a form of ethical subjectivism, defenders of the perspective that divine command theory is not a form of ethical subjectivism say this is based on a misunderstanding: that divine command proponents claim that moral propositions are about what attitudes God holds, but this understanding is deemed incorrect by some, such as Robert Adams who claims that divine command theory is concerned with whether a moral command is or isn't "contrary to the commands of (a loving) God".
[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.