In Experiments in Living: A Study of the Nature and Foundation of Ethics or Morals in Light of Recent Work in Social Anthropology, Macbeath’s themes are concerned with the nature and the knowledge of our duties and obligations, the principles according to which they are determined and the ways in which we discover them—whether they are regarded as duties to obey or rules to realize ends. Accordingly, he deals mainly with the outward and visible side of morality, the sorts of acts which are right and the kinds of ends which are good, the patterns of behaviour and the institutions and ways of life in which they find expression. Throughout his treatment of ethics and the moral life, the author defends the assumption that the main structure of the moral life, the nature of the moral idea and the grounds of moral obligation are in principle the same everywhere and for all people; and that, therefore, only a theory which will account for the moral judgments of all persons can be regarded as a satisfactory ethical theory. Nevertheless, Macbeath contends that if there is an identity principle underlying the moral judgments of all humankind, it must be compatible with a great diversity in the sorts of acts which are regarded as right and in the states of affairs which are regarded as good by different peoples. The author contextualizes his subject through the study of the moralities of contemporary primitive peoples—Trobriand Islanders, a Bantu tribe, Australian aborigines and Crow Indians. He draws on such groups partly in order to show the wide range of facts for which ethical theory has to account and partly because the contrasts between the ways of life and the moral judgments of different peoples are more obvious in the simpler conditions of primitive life, just as others become clearer in larger and more complex societies. Overall, throughout his discussions of primitive contemporary peoples, Macbeath holds that the way of life of every people known to history or anthropology is an attempt to embody a moral ideal, the elements of which are determined by 1) the desires and dispositions of human nature, i.e., persons are rational and self-conscious, and 2) by the conditions of cooperation between individuals which are necessary for the realization of selves in their unitary character. Furthermore, he argues that the good life is not good in spots or patches to which the rest of it is mere means, but throughout. As for personal character, he purports that it is improved and moral goodness realized by doing whatever is right in the circumstances, whether it be removing rubbish that disfigures a street or ‘the rubbish that lies in the way of knowledge’. Thus, Macbeath tries to break down the separation between moral duties, on the one hand, and social, economic, political, religious or legal duties, on the other. Toward the end of his lectures/text, the author acknowledges that he has been concerned with the life of man between birth and death, with nothing more than occasional side glances at the cosmic arena in which life is lived. This is not because he considers metaphysical and theological speculations idle or unimportant; it is rather because he chose as his subject the last, and perhaps the least, though not the least important, of the subjects prescribed by Lord Gifford—the nature of morality and the grounds of moral obligation—and because he is convinced that these can be discovered by an analysis of moral consciousness and the consideration of man as a person among persons, without reference to any metaphysical or theological system. If his analysis is sound, Macbeath believes there is one and only one thing which is absolutely and unconditionally good, moral goodness, and the goodness of conscientiously doing that which we believe to be right and trying to realize what we believe to be good. In turn, he argues that there is one and only one absolute evil, the evil will: the deliberate doing that which we believe to be wrong, not because we believe it to be wrong, but despite the belief that it is wrong. Importantly, for the author, this would still be so, and the duty of realizing the one and avoiding the other would be unconditionally binding, even if there were nothing beyond the grave, and even if there were no answer from the universe to one’s cry for cosmic support in his or her moral struggle expect the echo of his or her own voice. In the end, Macbeath concludes that though the conclusions he arrives at about the moral life do not seem to him to derive their justification or authority from any metaphysical or theological system, they are not without metaphysical implications. They have to be taken into account in constructing cosmological systems, and any system which does not leave room for them seems to the author to be necessarily false. But, he insists, if we are to use them as data or premises for such construction, it is all the more important that they should themselves be independently established.