does not require morality to exist objectively; Linville considers the view that this will lead to moral scepticism or antirealism. C. S. Lewis argued that, if evolutionary naturalism is accepted, human morality cannot be described as absolute and objective because moral statements cannot be right or wrong. Despite this, Lewis argued, those who accept evolutionary naturalism still act as if objective moral truths exist, leading Lewis to reject naturalism as incoherent. As an alternative ethical theory, Lewis offered a form of divine command theory which equated God with goodness and treated goodness as an essential part of reality, thus asserting God's existence. J. C. A. Gaskin challenges the first premise of the argument from moral objectivity, arguing that it must be shown why absolute and objective morality entails that morality is commanded by God, rather than simply a human invention. It could be the consent of humanity that gives it moral force, for example. American philosopher Michael Martin argues that it is not necessarily true that objective moral truths must entail the existence of God, suggesting that there could be alternative explanations: he argues that naturalism may be an acceptable explanation and, even if a supernatural explanation is necessary, it does not have to be God (polytheism is a viable alternative). Martin also argues that a non-objective account of ethics might be acceptable and challenges the view that a subjective account of morality would lead to moral anarchy. William Lane Craig has argued for this form of the moral argument. Argument for conscience Related to the argument from morality is the argument from conscience, associated with eighteenth-century bishop Joseph Butler and nineteenth-century cardinal John Henry Newman. Newman proposed that the conscience, as well as giving moral guidance, provides evidence of objective moral truths which must be supported by the divine. He argued that emotivism is an inadequate explanation of the human experience of morality because people avoid acting immorally, even when it might be in their interests. Newman proposed that, to explain the conscience, God must exist. British philosopher John Locke argued that moral rules cannot be established from conscience because the differences in people's consciences would lead to contradictions. Locke also noted that the conscience is influenced by "education, company, and customs of the country", a criticism mounted by J. L. Mackie, who argued that the conscience should be seen as an "introjection" of other people into an agent's