Non-cognitivism

Non-cognitivism is the meta-ethical view that ethical sentences do not express propositions (i.e., statements) and thus cannot be true or false (they are not truth-apt). A noncognitivist denies the cognitivist claim that "moral judgments are capable of being objectively true, because they describe some feature of the world." If moral statements cannot be true, and if one cannot know something that is not true, noncognitivism implies that moral knowledge is impossible.

Non-cognitivism entails that non-cognitive attitudes underlie moral discourse and this discourse therefore consists of non-declarative speech acts, although accepting that its surface features may consistently and efficiently work as if moral discourse were cognitive. The point of interpreting moral claims as non-declarative speech acts is to explain what moral claims mean if they are neither true nor false (as philosophies such as logical positivism entail). Utterances like "Boo to killing!" and "Don't kill" are not candidates for truth or falsity, but have non-cognitive meaning.

Emotivism, associated with A. J. Ayer, the Vienna Circle and C. L. Stevenson, though first defended by Axel Hägerström in the early 1900s, suggests that ethical sentences are primarily emotional expressions of one's own attitudes and are intended to influence the actions of the listener. Under this view, "Killing is wrong" is translated as "Killing, boo!" or "I disapprove of killing."

A close cousin of emotivism, developed by R. M. Hare, is called universal prescriptivism. Prescriptivists interpret ethical statements as being universal imperatives, prescribing behavior for all to follow. According to prescriptivism, phrases like "Thou shalt not murder!" or "Do not steal!" are the clearest expressions of morality, while reformulations like "Killing is wrong" tend to obscure the meaning of moral sentences.

Other forms of non-cognitivism include Simon Blackburn's quasi-realism and Allan Gibbard's norm-expressivism.

As with other anti-realist meta-ethical theories, non-cognitivism is largely supported by the argument from queerness: ethical properties, if they existed, would be different from any other thing in the universe, since they have no observable effect on the world. People generally have a negative attitude towards murder, which presumably keeps most of us from murdering. But does the actual wrongness of murder play an independent role? Is there any evidence that there is a property of wrongness that some types of acts have? Some people might think that the strong feelings we have when we see or consider a murder provide evidence of murder's wrongness. But it is not difficult to explain these feelings without saying that wrongness was their cause. Thus there is no way of discerning which, if any, ethical properties exist; by Occam's razor, the simplest assumption is that none do. The non-cognitivist then asserts that, since a proposition about an ethical property would have no referent, ethical statements must be something else.

Arguments for prescriptivism focus on the function of normative statements.

Prescriptivists argue that factual statements and prescriptions are totally different, because of different expectations of change in cases of a clash between word and world. In a descriptive sentence, if one premises that "red is a number" then according to the rules of English grammar said statement would be false. Since said premise describes the objects "red" and "number", anyone with an adequate understanding of English would notice the falseness of such description and the falseness of said statement. However, if the norm "thou shalt not kill!" is uttered, and this premise is negated (by the fact of a person being murdered), the speaker is not to change his sentence upon observation of this into "kill other people!", but is to reiterate the moral outrage of the act of killing. Adjusting statements based upon objective reality and adjusting reality based upon statements are contrary uses of language; that is to say, descriptive statements are a different kind of sentence to normative statements. If truth is understood according to correspondence theory, the question of the truth or falsity of sentences not contingent upon external phenomena cannot be tested (see tautologies).