 The Objection from Instrumentalism. Stevenson’s theory may seem to be an “instrumentalist” theory that explains the meaning of moral sentences by appealing to the illocutionary acts they are typically used to perform, that is, to their typical illocutionary forces. However, a great many uses of moral sentences fail to have such force. For example, when moral sentence 1 is used in utterances of sentences 2 or 3, it is used without its usual expressive force.