How were Charles Darwin’s ideas misused in social Darwinism and eugenics?

Charles Darwin’s scientific theories were frequently misused to justify ideologies that he did not support. While Darwin was an abolitionist, his work was distorted to provide a veneer of scientific legitimacy to social Darwinism and eugenics, both of which relied on biological determinism to advocate for the marginalization or elimination of those deemed socially unfit.1

Social Darwinism

Social Darwinists, most notably Herbert Spencer, incorrectly applied the biological concept of natural selection to human society. They argued that human life was a struggle for existence governed by the "survival of the fittest," using this to justify laissez-faire capitalism, class stratification, and racist or imperialist policies. Darwin himself found Spencer’s speculative extensions of his work to be of no scientific use.234

Eugenics

The eugenics movement used Darwin’s account of evolution to argue that humanity could and should control its own future through selective breeding. Proponents categorized individuals into "good stock" or "defective stock," leading to programs of positive eugenics (promoting reproduction of the elite) and negative eugenics (restricting the breeding of the "unfit"). These movements were ethically abhorrent, as they sought to use scientific concepts to validate discrimination and the systematic exclusion of vulnerable populations.51