excluding any form of genetic engineering. We should not step over the line that delineates treatment from enhancement.34
However, this way of thinking of medical genetics makes at least two questionable assumptions: (1) that we have a clear and uncontroversial account of health and disease, and (2) that the goal of treating diseases is morally legitimate, while other goals are not. To examine these assumptions, we need to take a quick look at discussions about the concepts of health and disease.
The bioethics literature contains a thoughtful debate about the definitions of health and disease and it is not my aim to survey that terrain here.35,36 However, I will distinguish between two basic approaches to the definition of health, a value‐neutral (or descriptive) approach and a value‐laden (or normative) one.37 According to the value‐neutral approach, health and disease are descriptive concepts that have an empirical, factual basis in human biology. Boorse defended one of the most influential descriptive approaches to health and disease: a diseased organism lacks the functional abilities of a normal member of its species.38 To keep his approach value‐neutral, Boorse interprets “normal” in statistical terms, i.e., “normal” = “typical.” Daniels expands on Boorse’s account of disease by suggesting that natural selection can provide an account of species‐typical functions: functional abilities are traits that exist in populations because they have contributed to the reproduction and survival of organisms that possessed them.39 Thus a human with healthy lungs has specific respiratory capacities that are normal in our species, and these capacities have been “designed” by natural selection. A human who lacks these capacities, such as someone with cystic fibrosis or emphysema, has a disease.
According to the value‐laden approach, our concepts of health and disease are based on social, moral, and cultural norms. A healthy person is someone who falls within these norms; a diseased person deviates from them. Someone who deviates from species‐typical functions could be considered healthy in a society that views that deviation as healthy: although schizophrenia has a biological basis, in some cultures schizophrenics are viewed as “gifted” or “sacred,” while in other cultures they are viewed as “mentally ill.” Likewise, some cultures view homosexuality as a disease, while others do not.40–42
Many different writers have tried to work out variants on these two basic approaches to health and disease, and some have tried to develop compromise views,43,44 but suffice it to say that the first assumption mentioned above – i.e., that we have a clear and uncontroversial account of health and disease – is questionable.
Even if we lack an uncontroversial account of disease, we could still ask whether either of the two basic approaches would condemn genetic enhancement unconditionally. Consider the descriptive approach first. If statements about disease merely describe deviations from species‐typical traits, does it follow that we may perform genetic interventions to treat diseases but not to enhance otherwise healthy people? Since we regard the concept of disease as descriptive, we cannot answer this question without making some normative assumptions. Saying that someone has a disease is like saying that he or she has red hair, is five feet tall, or was born in New York City. These descriptions of that person carry no normative import. Hence the descriptive account of disease, by itself, does not provide us with a way of drawing a solid moral line between therapy and enhancement. For this approach to disease to draw moral boundaries between therapy and enhancement, it needs to be supplemented by a normatively rich account of the rightness of therapy and wrongness of enhancement.
Perhaps the normative approach fares better than the descriptive one. If we accept this view, it follows that therapy has some positive moral value, since therapy is an attempt to treat diseases, which are defined as traits or abilities that do not fall within social or cultural norms. If it is “bad” to have a disease, then we are morally justified in performing interventions that attempt to treat or prevent diseases, since these procedures impart “good” states of being. Thus this normative approach implies that therapy is morally right. But does it imply that enhancement is morally wrong? The answer to this question depends, in large part, on the scope of the concepts of health and disease. If we hold that the concept of health defines a set of traits and abilities that should be possessed by all members of society and that any deviations are diseases, then any intervention that results in a deviation from these norms would be viewed as immoral. Hence, enhancement would be inherently immoral. But this account of health and disease is way too broad; there must be some morally neutral traits and abilities. If there are no morally neutral traits and abilities, then any person that deviates from health norms is “sick.” This view would leave very little room for individual variation, to say nothing of the freedom to choose to deviate from health norms. If we accept a narrower account of health and disease, then we will open up some room for morally acceptable deviations from health norms. But this interpretation implies that enhancement interventions could be morally acceptable, provided that they do not violate other moral norms, such as nonmaleficence, autonomy, utility, and so on. Enhancement would not be inherently wrong, on this view, but the rightness or wrongness of any enhancement procedure would depend on its various factual and normative aspects.
The upshot of this discussion is that neither of the two main approaches to health and disease provides us with solid moral boundaries between genetic enhancement and genetic therapy. One might suggest that we examine alternative approaches, but I doubt that other, more refined theories of health and disease will provide us with a way of drawing sharp moral boundaries between genetic enhancement and genetic therapy. Perhaps we should look at other ways of endowing the distinction with moral significance.
The Goals of Medicine
A slightly different approach to these issues asserts that genetic therapy is on solid moral ground because it promotes the goals of medicine, while genetic enhancement promotes other, morally questionable goals. But what are the goals of medicine? This is not an easy question to answer, since medicine seems to serve a variety of purposes, such as the treatment of disease, the prevention of disease, the promotion of human health and well‐being, and the relief of suffering. Many of the so‐called goals of medicine, such as the prevention of disease and the promotion of human health, may also be promoted by procedures that we would classify as forms of enhancement.45 For example, some writers have suggested that we might be able to perform genetic interventions that enhance the human immune system by making it better able to fight diseases, including cancer.46 Most people would accept the idea that providing children with immunizations against the measles, mumps, and rubella promotes the goals of medicine. If we accept the notion that ordinary, nongenetic enhancement of the immune system promotes the goals of medicine, then shouldn’t we also agree that genetic enhancements of the immune system serve the same goals? And what about other forms of healthcare, such as rhinoplasty, liposuction, orthodontics, breast augmentation, hair removal, and hair transplants? If these cosmetic procedures serve medical goals, then cosmetic uses of genetic technology, such as somatic gene therapy for baldness, and germline gene therapy for straight teeth, would also seem to serve medical goals. Finally, consider the procedures that are designed to relieve suffering, such as pain control and anesthesia. If we can develop drugs to promote these goals, then why not develop genetic procedures to meet similar objectives? It is