I have been interested in the above topic since taking a wonderful graduate seminar in the subject about 30 years ago from Richard J. Blackwell at St. Louis University. Recently a friend introduced me to a paper on the topic, “Bridging the Is-Ought Divide: Life is. Life ought to act to remain so,” by Edward Gibney who argues (roughly) that the naturalistic fallacy has no force. Gibney is not a professional philosopher, but I found myself receptive to his argument nonetheless.
Like most philosophers I was introduced early in my career to the naturalistic fallacy—the idea that you can’t get an ought from an is—but I have never found the argument convincing. This quote from Daniel Dennett expresses my view clearly.
If ‘ought’ cannot be derived from ‘is,’ just what can it be derived from?…ethics must be somehow based on an appreciation of human nature—on a sense of what a human being is or might be, and on what a human being might want to have or want to be.
While it is obvious that our moral behaviors arose in our evolutionary history, philosophers typically object that this is a fact about ethics that doesn’t imply any values. But again, I have never found this objection satisfying. If facts about our nature don’t tell us something about what we should value, then where might we get ethics from? I understand that a straightforward deduction of ought from is doesn’t follow, but surely we can infer something about what we ought to do from what is. However I acknowledge that I am in a minority on this question, as most philosophers accept the naturalistic fallacy. Perhaps they just don’t like more of their field being taken over by scientists!
In the end evolutionary ethics is an extension of evolutionary theory into another realm. Our bodies and our minds are now understood best from an evolutionary perspective, and so too should our behaviors in the moral realm. I think that evolutionary epistemology helps resolve the mind/body problem, and now evolutionary ethics helps resolve the is/ought problem.
Still philosophers would object to a number of issue in the paper, including Gibney’s basic syllogism:
3) p ought to act in aid its continued existence.
First, they might object that “just because p is doesn’t mean that p ought to be.” By simply stating this, Gibney is begging the question.
Second, they might say, “if p wants to exist it should act so in ways that help it to continue to exist, but this is a survival imperative and not a moral imperative. And those aren’t the same thing.” In other words Gibney is confusing what behaviors help us survive with moral behaviors. While the two sometimes coincide, often they don’t. (Killing you quickly before you kill me might aid my survival but not be moral.)
I agree that there are more to moral imperatives than survival imperatives; nonetheless survival imperatives are a prerequisite for moral imperatives. In other words, oughts that aid survival are necessary but not sufficient conditions for morality. So while we cant deduce morality from human nature, we can infer a large part of it.