In its recent issue, Reason Papers published an informative review essay by philosopher Gary James Jason of Cal State University: “Selling Eugenic Killing: The Nazi Propaganda Campaign to Support the Liquidation of the Disabled.”
Quote: “Positive eugenics means promoting breeding ‘superior individuals’ from ‘good stock.’ Negative eugenics refers to prohibiting the breeding of children of ‘defective stock.’ However, I would suggest that many such policies are on a slippery slope.”

Related: I discuss the National Socialists’ eugenics program, in Section 16 of my Nietzsche and the Nazis: