Reproductive choice, enhancement, and the moral continuum argument.

It is often argued that it does not matter morally whether biomedical interventions treat or prevent diseases or enhance nondisease traits; what matters is whether and how much they promote well-being. Therapy and enhancement both promote well-being, the argument goes, so they are not morally distinct but instead continuous. I provide three reasons why this argument should be rejected when it is applied to choices concerning the genetic makeup of future people. First, it rests on too simple a conception of the badness of disease. Second, it wrongly assumes that disease avoidance and enhancement can proceed with similar accuracy. Third, it overlooks that disease avoidance tends to be more urgent than enhancement from the point of view of distributive justice. Although none of these reasons establishes a firm therapy-enhancement distinction, they show that a continuum model is not an attractive alternative.