Based on an unfinished manuscript by the late philosopher Dallas Willard, this book makes the case that the 20th century saw a massive shift in Western beliefs and attitudes concerning the possibility of moral knowledge, such that knowledge of the moral life and of its conduct is no longer routinely available from the social institutions long thought to be responsible for it. In this sense, moral knowledge—as a publicly available resource for living—has disappeared. Via a detailed survey of main developments in ethical theory from the late 19th through the late 20th centuries, Willard explains philosophy’s role in this shift. In pointing out the shortcomings of these developments, he shows that the shift was not the result of rational argument or discovery, but largely of arational social forces—in other words, there was no good reason for moral knowledge to have disappeared.