[Negative and positive eugenics: meanings and contradictions].
Eugenics constitutes an important subject of debate, associated with current biogenetics improvements. Considering that the central point in eugenics has always been the preoccupation with future generations' health and constitution, and that the use of scientific means and knowledge for the birth of a physically and mentally healthy child can be considered a eugenic action, this paper tries to analyze the meanings and contradictions of negative and positive eugenics actions, constructed concomitantly with 20th-century technical-scientific improvements. The meanings range, respectively, between limiting or stimulating human reproduction, at the beginning of this century, and preventing diseases or improving physical and mental characteristics, nowadays. In the implantation of actions, contradictions were produced, such as the discrimination and elimination of many people in view of one ideal man, the biologization of eminently social factors, the defense of a supposed scientific neutrality and the indiscriminate use of the reproductive choice right.