Karl Paul Reinhold Niebuhr (; June 21, 1892June 1, 1971) was an American
theologian,
ethicist,
public intellectual, commentator on politics and public affairs, and professor at
Union Theological Seminary for more than 30 years. The brother of another prominent theological ethicist,
H. Richard Niebuhr, he is also known for authoring the
Serenity Prayer, and received the
Presidential Medal of Freedom in 1964. Among his most influential books are
Moral Man and Immoral Society and
The Nature and Destiny of Man, the second of which
Modern Library ranked one of the top 20 nonfiction books of the twentieth century. Starting as a minister with working-class and labor class sympathies in the 1920s oriented to
theological pacifism, he shifted to
neo-orthodox realist theology in the 1930s and developed the theo-philosophical perspective known as
Christian realism. He attacked utopianism as ineffectual for dealing with reality, writing in
The Children of Light and the Children of Darkness (1944):
- "Man's capacity for justice makes democracy possible; but man's inclination to injustice makes democracy necessary."