Health is one place where the descriptive and normative seem to converge, allowing us to infer “ought” from “is.” That smoking is unhealthy is a reason not to smoke. Hence, all else being equal one ought not to smoke. In the same way, health is one place where biology seems to serve up normative lessens. As health turns in large measure on the state of the organism and the functioning of its biological systems, the study of what is or is not “good for us” biologically provides us with ever more accurate guides to what we should and should eat or drink or do to ourselves.
That we can capitalize on this convergence of “ought” and “is” in health to construct a picture of how we ought to live more broadly has tempted moral philosophers since Plato. Perhaps virtue can be understood as “good for us” in the sense that doing what is healthy is good for us, as contributing to our overall well being. Plato tries in the Republic to cash this out in a theory of a properly ordered soul. Update this a bit with the help of modern psychology and we have (in the crudest of outline) modern versions of Virtue Ethics and with that a plausible role for evolutionary thinking. If the theory of evolution can help us better understand the conditions of psychological well being, it might there have a fairly direct contribution to make to moral theory.
Now, a problem with all this is visible from the get go. Health can bridge the gap between “is” and “ought” only if we assume that health is a good thing. Without this there is no move from “smoking is unhealthy” to “one ought not to smoke” just as we cannot go from “smoking makes you look cool” to “one ought to smoke” without assuming looking cool is a good thing. There are people who will say “looking cool isn’t important to me”, and attempts to get them to smoke on the basis of coolness will fall on deaf ears. What do we say to people who say “being healthy isn’t important to me”?
One response would be to concede we have nothing to say to such people other than they’re not like us in that respect, and perhaps that is the best response. Virtue ethicists have typically given into the temptation to try to answer that question in a more substantive way however, by trying to ground the goodness of health (or well being more broadly) in something more objective. (As a side note, I think it’s interesting that most people find the resulting theories of some more basic good less plausible than the claim they are supposed to support.) There are some good philosophical reasons for wanting to do this. If we can say why not valuing health is irrational, for example, we say why some preferences are irrational, and that we can have irrational preferences is something most people find plausible I think. Suffice to say, however, this remains a difficult issue.
By way of conclusion, two quick comments, one on evolutionary biology and the other on Mencius. First, once again those looking for normative guidance from evolutionary biology are I think looking in the wrong place. Biology might help explain our preferring health to illness, but it doesn’t provide the normative basis to say it is truly better. Secondly, as I read him Mencius has something in common with Western Virtue Ethicists in trying to go from a sense of what is psychologically healthy and “normal”–the development of the our capacities for commiseration, shame, deference and drawing distinctions–to what is morally desirable. As I argued last time, his project can draw support from the modern vindication of the underlying psychological claims. But he too faces the difficulty in answering a sincere outlier who doesn’t value normal psychological development. As I read him, his response is to consider that person rather literally as not one of us.