A. J. Ayer had already written that ethical statements were factually meaningless but served to express favorable or unfavorable feelings toward something. So someone who said “capital punishment is just” may be expressing an attitude like “Hurray for capital punishment.” “Stealing is wrong” is equivalent to saying “Boo for stealing.” Charles L. Stevenson (1908–79) furthered the analytic approach to philosophy in his book Ethics and Language and in a series of articles.

According to Stevenson, statements making use of value predicate terms like good or right are expressions of a felt “pro-attitude” that their readers or listeners are expected to share. On the other hand, statements containing value terms like wrong or evil reveal a disapproving attitude. Stevenson's view became known as emotivism.

Sometimes a disagreement in attitude results from a disagreement about the facts of the case, and the conflict might disappear if an agreement on the facts is reached. At times, however, two people may agree about the facts surrounding capital punishment (or abortion, euthanasia, or some other issue), while one regards it as “state-approved murder” and the other regards it as the “highest justice.” The disagreement can only be resolved by a change of attitude, Stevenson thought. The linguistic component of such changes will be “persuasive definitions,” and in the present dispute about capital punishment redefinitions of murder and justice. But this process of redefinition is likely to be carried out rhetorically, and so one attitude that does not result from a mistake of fact is no more reasonable or unreasonable than another.