Which C.S. Lewis book explores the dangers of abolishing traditional moral values?

The C.S. Lewis book that explores the dangers of abolishing traditional moral values is The Abolition of Man. It was published in 1943 and developed from three lectures Lewis delivered at the University of Durham.

The book argues that moral judgments are not merely subjective expressions of feeling. Lewis defends what he calls the Tao, a cross-cultural body of basic moral principles that he believes underlies many ethical traditions. He warns that attempts to control nature can ultimately become attempts by some people to control other people.

The title can mislead readers into expecting a biological or scientific discussion of human extinction. Lewis is instead examining education, ethics, and the consequences of rejecting objective value. The work is shorter and more philosophical than his fictional books, but it remains one of his most frequently discussed nonfiction works.