From Wikipedia, the emotivism is defined as the set of ethical theories that, in the Ethics and Philosophy of twentieth century, especially at the Anglo-Saxon philosophers, argue that moral judgments have no cognitive value but that emotions and feelings that accompany them determine an incentive conditioning to act morally.
Immanuel Kant brought an indictment of psychologism. For the German philosopher, in fact, this conception was irreducible to the feeling that could never be confused with morality. Feeling is something impulsive, weak, inconsistent, on which morality can not rely on ":a certain sweetness of soul that passes easily into a warm sense of piety, is beautiful and lovable, because it reveals a certain participation in the events of others [...] but this good-natured sentiment is weak and blind. "
The term "emotivism", introduced in the syntax of scientific language, has been created in the last century with the recognition of semantics of use and as distinction between indicative and emotional valence of human discourse implemented in the article: 'The meaning of meaning' written by C.K. Ogden and I.A. Richards. In order that the term ‘emotivism’ had a less extended sense, it is necessary to wait for the definition of Ayer. For him the word "emotivism" merely indicates an attempt to reduce the ethical discourse to the emotional use.
For Charles Leslie Stevenson moral judgments must be traced to personal emotional causes, but rather than in feelings, morality has its origin in the psychological sphere and the opposing moral attitudes can be explained as those that occur with a sense of satisfaction.
Also for Stevenson moral judgments are of emotional and private nature, but rather than being direct expression of feelings, they refer to "attitudes", to psychological dispositions to approve or disapprove courses of action, and the contrasts between different moral attitudes develop in similar manner to the conflicts that arise in the realm of taste. Against the reduction of moral judgments to emotions, theoretical proposals, such as Hare’s, have tried to re-establish the specific nature of moral language, connecting it to a form of practical rationality.
So, if starting from Principia Ethica of G. E. Moore (1903) research for an ethics free from naturalistic or metaphysical assumptions had begun to ponder on the meaning of moral terms commonly used, with the affirmation of emotivism, this application of the methods of analytical philosophy to ethics is seriously contested. The ethical emotionalism is a significant moment in the way, peculiar to the Anglo-Saxon moral philosophy of the twentieth century, which led to the affirmation of the studies on meta-ethics (at the expense, at least until the sixties, of normative ethics) and of analyses on the moral language .
The emotivism, in the radical formulation drawn by A.J. Ayer, is however a moment of profound criticism of the philosophical path because It supports the lack of meaning of moral statements.
The emotivism in its most complete and radical form consolidates, however, with the publication in 1936 of the work 'Language, Truth and Logic' by A.J. Ayer, a work in which the author, in accordance with the prescriptions of logical positivism, applies to the judgments of ethics and to the expressions of the mysticism the principle of verification.
The criterion used here to test the authenticity of those who present themselves as statements of fact is the criterion of verifiability. We say that a statement is significant in a factual sense for any given individual, if and only if it knows how to verify the proposition that the statement is intended to express. Specifically, if he knows what observations would lead him, under certain conditions, to accept the proposition as true or false.
The ethical emotivism refuses the status of verifiable expressions, and then all those propositions that express command, state of mind, moral convictions; the only propositions with sense are those to which is possible to apply the principle of verification, i.e. those that can be true or false.
The neo-positivist tradition before the Second World War considered the ethical propositions as meaningless, as not attributable to tautologies nor to empirical statements: the emblem of this condemnation is the script 'Language, Truth and Logic' by Ayer. The consequence of such conviction is that ethical propositions are nothing but expressions of feelings or emotions. From these assumptions, Stevenson builds on the ethical emotivism, that he at first distinguishes between empirical propositions and tautologies, on the one hand, and ethical propositions, on the other. While the former has a complete sense and a descriptive meaning, which gives rise to cognitive acts in the listener, the second (ethical one) has also an emotional meaning. In other terms they evoke emotions and feelings in those who listen. So the ethical propositions, despite the absence of descriptiveness, have, in their prescriptiveness, a precise meaning, which is an emotional one. To clarify this distinction, Stevenson uses a rather effective example: if I say "this man is a black", I formulate a proposition having descriptive and, consequently, a cognitive value (in fact, this proposition gives me information about the reality in front of me) . If I say "this is a black man," I formulate an emotional proposition, that rather than describing reality, elicits a negative feeling in the listener.
Then, when I express a proposition like "do so because it is a good deed," I am somehow providing descriptive elements, but end up being reabsorbed in the emotionality: in fact, when I say "do so because it is a good action ", rather than describe reality, I want to persuade you to act in a way which I think is positive. Stevenson insists on the impossibility of descriptive cogency of moral statements: compared to Ayer, he emphasizes the subjectivity of such statements, opening the door to a possible relativistic drift (stemming from the lack of objectivity of moral statements that allow me to define universally what is 'good').
Although very constructive, the road of emotivism is a path not entirely satisfactory. Considering emotivism as a meta-ethical theory that neglects the existence of moral disagreements and does not admit the normative value of evaluations, it incurs in the same charges of reductionism it introduces in relation to other theories. In this way, the emotionalism takes the dead end of reductionism.