Non-cognitivism says there is no ethical knowledge, because ethical statements are not statements that can be proved true or false. Thus "Euthanasia is wrong" is not a statement about facts. Non-cognitivists make a distinction between facts and values
Emotivism will not tell you how to live a moral life, but helps us understand moral statements: as action guiding and as conveying certain attitudes. A.J.Ayer said "ethical terms do not serve only to express feelings. They are calculated also to arouse feeling, as so to stimulate action". This means when we talk about "good" and "bad" we are expressing emotional states of approval and disapproval; any other interpretations are are meaningless. Emotivism comes from the vienna circle and developed from a theory called logical positivism which holds that any truth claim must be tested by sense experience. Ethical statements cannot be tested by sense experience, so they are not truth claims and can only express feelings.
Hume's fork (supported by Ayer): Analytic statements-statements of mathematics or logic and Synthetic statements- statements of science, history or ordinary life.
Ayer does not believe ethical statements have no meaningful function. It cannot be compared to normative ethical theories and it does not give any reason why one's feelings should be better than another's or why it should stimulate one's actions rather than those of another. It reduces ethical statements to a level where they are nothing.
Stevenson gave a more detailed version of emotivism and did not use the verification principle but discussed the emotive meaning of words - many moral terms are both descriptive and emotive, expressing also what we feel about them. So when one makes a moral judgement they are not only giving vent to his feelings, but also trying to influence others' attitudes. Emotivism connects "caring", "approving" and "disappointing" with the very meaning of ethical words. This doesn't mean ethical statements can be based on emotions, these are not merely arbitrary but based on our experience of the world and how we want it to be. Stevenson saw ethical statements as not only expressions of emotion, but the result of attitudes based on fundamental beliefs, ethical disagreements between people are disagreements about fundamental principles.
Criticisms for Emotivism
Emotivism is sometimes known as the Boo/Hurrah Theory. A word such as "steal" invokes feelings about what happened-it is an interpretation of the event. Emotivism shows how ethical stataments wemake can depend on our attitudes, upbringing and feelings and so James Rachels criticised emotivism as being "simple subjectivism". He said it can lead to the notion that "where morality is concerned, there are no 'facts' and no one is 'right". Rachels points out that moral judgements appeal to reason; they are not just expressions of feeling. A statement like "I like chocolate" needs no reason, moral judgements do or else they are arbitrary.
Ayer suggests that ethical statements are more than expressions of feeling, but have the intention to stimulate others to act in the way they feel is right. Stevenson asked why one perons's feelings about a matter should be any better than those of another. All emotivism does is draw attention to the reasons why people have different opinions and then let other's decide. It has been shown that stimulating people through powerful and emotive speeches can have some unfortunate consequences eg. Hitler. Emotivism may be seen as allowing complete freedom of action on the grounds that everyone's opinion is equally valid and so everyone can do as they like.
Hare attacked Hume's view that it is impossible to deduce a prescriptive statement from a descriptive statement and attempted to show that ethical language is presciptive. The role of ethical statements is to say what ought to be done and such prescriptions are moral because they are universal. Hare argues that universal prescriptivism gives a better account of the nature of ethical statements than others. They try to explain what we are doing when we make ethical judgements. Hare says that although this approach is useful, universal presciptivism is superior. Ethical statements are prescriptive which means they do not state facts and are not true or false, but they express our will or wishes; they are imperatives. Hare argues that however we use the word "good", we always do so in relation to a set of standards
A good chair is one that supports your back, is comfortable and fit for the purpose.
The word "good" has a descriptive meaning. If used in a moral sense, we are using a set of standards that apply to a person or an action and we commend that person or action. This means it also has a prescriptive meaning. This can happen with any words that commend and describe, such as "steal" and "murder".
Hare is saying that there is a difference between the descriptive meaning and the prescriptive meaning, when we use words with and ethical meaning, we use them prescriptively. Prescriptivism holds that to achieve consistency in moral judgements when we say that someone else ought to do something, we ought to do it as well. We are not only saying "Boo to stealing" with prescriptivism, but that stealing is wrong as we would not prescibe it for ourselves.
Criticisms for Prescriptivism
If moral judgements are founded on prescriptions, this still does not mean there is a valid reason for following one person's presciptions rather than another's. Hare recognised that morals are not necessarily universal and one's preference may differ from another's. The only constraint is that one should put oneself "in another's shoes" before making the judgement.
Prescriptivism says that "ought" judgements are universalisable prescriptives or imperatives and not truth claims-they are not objective and there is no moral knowledge or moral truth. This goes against the way people approach ethics-in general people think it is wrong to commit crime. According to Hare, we could just as easily choose the opposite if we wished and we could change our moral principles as we choose or as our circumstances alter.