Social Darwinism was used during the latter portion of the 19th century and the first half of the 20th century as a biological justification to further the aims of laissez-faire capitalism, immigration control, eugenics, colonialism and, in one its most extreme applications, Nazism. Charles Darwin's theory of natural selection, also known as "the survival of the fittest," was adapted by various groups and factions as a means of overriding moral and ethical restraints regarding the subjugation or elimination of the weak by the strong. Although social Darwinists viewed competition among groups and individuals as a normal part of human evolution, it was used in the political arena to promote racism, nationalism and military aggression.
The premise of social Darwinism is that the privileges and status enjoyed by the powerful and wealthy members of society are the results of their personal traits evolving through natural selection. Because these traits were not found in the powerless and poor members of society, it was believed that it would be best for the human race to let these individuals and groups perish. By the 20th century, this misappropriation of Charles Darwin's theories led to forced sterilization, armed conflicts and ethnic cleansing.
The 19th century sociologist and political theorist, Herbert Spencer, is considered to be the primary author of what became known as "social Darwinism" and is believed to have been the first writer to use the phrase "survival of the fittest." Charles Darwin stated that he was not a social Darwinist, as did many of those who supported his theories concerning evolution. The term "social Darwinism" came into prominent use as a pejorative after the atrocities of World War II and the Holocaust came to light, and there are very few serious advocates of social Darwinism in the 21st century.