On the Naturalistic Fallacy: A conceptual basis for evolutionary ethics

From the book : Evolutionary Psychology 2: 32-46.
In debates concerning evolutionary approaches to ethics the Naturalistic Fallacy (i.e., deriving values from facts or “ought” from “is”) is often invoked as a constraining principle.
For example, Stephen Jay Gould asserts the most that evolutionary studies can hope to do is set out the conditions under which certain morals or values might have arisen, but it can say nothing about the validity of such values, on pain of committing the Naturalistic Fallacy.
Such questions of moral validity, he continues, are best left in the domain of religion.
This is a common critique of evolutionary ethics but it is based on an insufficient appreciation of the full implications of the Naturalistic Fallacy.
Broadly conceived, the Naturalistic Fallacy rules out any attempt to treat morality as defined according to some pre-existent reality, whether that reality is expressed in natural or non-natural terms.
Consequent to this is that morality must be treated as a product of natural human interactions.
As such, any discipline which sheds light on the conditions under which values originate, and on the workings of moral psychology, may play a crucial role in questions of moral validity.
The authors contend that rather than being a constraint on evolutionary approaches to ethics, the Naturalistic Fallacy, so understood, clears the way, conceptually, for just such an approach.