Which C.S. Lewis book argues that human beings should not be reduced to purely biological explanations?

The C.S. Lewis book arguing against reducing human beings to purely biological explanations is The Abolition of Man.

Published in 1943, The Abolition of Man developed from three lectures Lewis delivered at the University of Durham in 1943. The book examines education, moral judgment, and the danger of treating values as nothing more than subjective feelings or products of conditioning.

Lewis uses the term “the Tao” for a shared traditional framework of objective moral principles found across cultures. He argues that attempts to reshape human nature through purely instrumental science could ultimately undermine the qualities that make people human.

The work is not a biology textbook and does not reject scientific investigation. Its central concern is the relationship between moral knowledge, education, and technological power. The title refers to the possibility that a future generation could lose its humanity through the manipulation of human nature, rather than to the literal disappearance of the human species.