are only capable of converting a relatively small subset of all ethical claims into imperatives. Like Ross and Brandt, Urmson disagrees with Stevenson's "causal theory" of emotive meaning—the theory that moral statements only have emotive meaning when they are made to change in a listener's attitude—saying that is incorrect in explaining "evaluative force in purely causal terms". This is Urmson's fundamental criticism, and he suggests that Stevenson would have made a stronger case by explaining emotive meaning in terms of "commending and recommending attitudes", not in terms of "the power to evoke attitudes". Stevenson's Ethics and Language, written after Ross's book but before Brandt's and Urmson's, states that emotive terms are "not always used for purposes of exhortation." For example, in the sentence "Slavery was good in Ancient Rome", Stevenson thinks one is speaking of past attitudes in an "almost purely descriptive" sense. And in some discussions of current attitudes, "agreement in attitude can be taken for granted," so a judgment like "He was wrong to kill them" might describe one's attitudes yet be "emotively inactive", with no real emotive (or imperative) meaning. Stevenson is doubtful that sentences in such contexts qualify as normative ethical sentences, maintaining that "for the contexts that are most typical of normative ethics, the ethical terms have a function that is both emotive and descriptive." Philippa Foot's moral realism Philippa Foot adopts a moral realist position, criticizing the idea that when evaluation is superposed on fact there has been a "committal in a new dimension." She introduces, by analogy, the practical implications of using the word injury. Not just anything counts as an injury. There must be some impairment. When we suppose a man wants the things the injury prevents him from obtaining, haven’t we fallen into the old naturalist fallacy? Foot argues that the virtues, like hands and eyes in the analogy, play so large a part in so many operations that it is implausible to suppose that a committal in a non-naturalist dimension is necessary to demonstrate their goodness. Standard using and standard setting As an offshoot of his fundamental criticism of Stevenson's magnetic influence thesis, Urmson wrote that ethical statements had two functions — "standard using", the application of accepted values to a particular case, and "standard setting", the act of proposing certain values as those that should be accepted — and that Stevenson confused them. According to Urmson, Stevenson's "I approve