Eugenics is the "effort to breed better humans - by encouraging the reproduction of people with 'good' genes and discouraging those with 'bad' genes" (Cold Spring Harbor Lab Archive). Although the ideology of eugenics peaked in the first half of the 20th century, the eugenic mentality appears to be alive and well today in the fields of reproductive technology, public health, and bioethics.
Today's eugenicists shy away from racist proposals to "purify the human race." Instead, they speak of the quest to make human beings the way they want them to be: perfect.
Those who are too small, sick, weak, or dependent to meet this standard of perfection and 'high quality of life' may be eliminated through the violence of abortion, infanticide, or euthanasia. Individual lives in the eugenics worldview only have value as long as others want them or judge them to be "lives worthy of living." Once those lives have become a burden or an obstacle to humanity's quest for perfection or one's own personal wants and desires, then they can be eliminated in the name of "freedom" or even "compassion."
All human beings - no matter what their physical condition or degree of dependency - possess intrinsic dignity and worth. As such, each and every human deserves nurture and protection. The way to work for a better world is not to kill people we label as "problems" but to care for those in need of our physical, emotional, or spiritual help.
For more information: American Bioethics Advisory Commission.