Which C.S. Lewis book presents a fictional dialogue about abolishing objective values?

The Abolition of Man presents C.S. Lewis’s argument about abolishing objective values.

Published in 1943, The Abolition of Man developed from three lectures Lewis delivered at the University of Durham. In the book, he criticizes an approach to education that treats moral judgments as merely subjective emotional responses. He argues that human societies depend on objective values and a shared moral order.

The title refers to the possible result of rejecting those values: not human liberation, but the loss of the qualities that make people fully human. The work is sometimes confused with Mere Christianity because both discuss moral reasoning, but The Abolition of Man is a shorter philosophical critique rather than a collection of broadcast-based Christian talks. Its themes include education, natural law, and the dangers of controlling human nature.