How was eugenics justified by social Darwinism?

Eugenics was justified by social Darwinism through the belief that improving the genetic quality of the human population would lead to a stronger, more evolved society. Supporters argued that by controlling reproduction and promoting "desirable" traits, society could progress and avoid what they saw as "degeneration" and "racial degeneration." This harmful ideology sought to apply the principles of natural selection to human societal issues, leading to discriminatory and unethical practices.