Edward Westermarck's extensive treatise investigates the psychological and historical foundations of ethical standards across human societies. The author argues that moral concepts are essentially generalizations of tendencies in certain phenomena to call forth moral emotions, specifically disapproval and approval. These emotions are classified as retributive, with disapproval acting as a form of resentment directed against the cause of pain, and approval serving as a retributive kindly emotion towards the cause of pleasure.
The work thoroughly analyzes the nature of these emotions, demonstrating their roots in animal behavior and primitive social instincts, particularly the mechanism of protective reaction. Westermarck explores how the application of moral judgments evolved from unreflecting custom to deeply considered ethical principles. Through vast ethnographical data, he examines the evolution of the moral consciousness regarding homicide, parental care, infanticide, human sacrifice, blood-revenge, hospitality, and slavery.
A central theme of the text is ethical subjectivism, arguing that because moral concepts are based on emotions rather than abstract truths, no absolute standard of morality exists independently of human feeling. The author examines how the apparent objectivity of moral judgments arises from the uniform nature of social custom, shared emotional constitutions, and the authority attributed to moral rules. Customs and laws serve as the earliest expressions of public indignation and approval, reflecting the values of the community at large.
The treatise contrasts early retributive customs, such as collective responsibility and blood-revenge, with more enlightened moral views that emphasize individual accountability and the reformation of the offender. Westermarck discusses the gradual expansion of altruistic sentiments, showing how the moral sphere expanded from narrow tribal circles to embrace humanity at large. Ultimately, the work posits that the study of ethics must be empirical and psychological, focusing on the moral consciousness as a factual phenomenon.
