SPENCER, HERBERT (1820–1903), was an English philosopher who became the most influential exponent of social evolutionism. Born in Derby, England, and educated largely in an atmosphere of religious dissent (and especially influenced by Quakers and Unitarians of the Derby Philosphical Society), Spencer combined a practical bent (for railway engineering, inventions, etc.) with a constant search for scientific principles. He became assistant editor at the Economist in London in 1848. After an early essay (1852) on the "development hypothesis" (concerning the laws of progress), he settled on evolution as the basic principle governing all change in the universe and began propagating a theory of evolution even before Charles Darwin's On the Origin of Species appeared in 1859.

The core of Spencer's literary output was published in several volumes under the general title A System of Synthetic Philosophy; this huge endeavor was left unfinished at Spencer's death. Its bearing on religion was...