When I first learned about the fact/value distinction in college, it really clicked for me. That something 'is' does not necessarily mean that it 'ought' to be. So I've come to the firm opinion that every ethical or moral system is predicated on at least one value (another was of saying opinion), regardless of whether that system claims to be "objective," "scientific," or "empirical." It is interesting how the purveyors of so-called objective morality are blind to their own values which shape their systems.
In a recent Scientific American there was a short blurb by Michael Shermer in praise of Sam Harris' The Moral Landscape. Harris' "neuroethics" is described thus:
Sam Harris . . . wields a sledgehammer to the is-ought wall. Harris’s is a first-principle argument, backed by copious empirical evidence woven through a tightly reasoned narrative. The first principle is the well-being of conscious creatures, from which we can build a science-based system of moral values by quantifying whether or not X increases or decreases well-being.
Allow me to point out the implicit opinions in Harris' system. I should note that I have not read this book, but I probably should. I will post corrections if I find that I am portraying Harris' argument unfairly or inaccurately.
First is the question of how the "first" principle came to be first. I am not sure how Harris would argue that this principle, as opposed to any other, should be the ultimate principle. As a matter of fact, Ayn Rand's system of objective morality had a drastically different first principle, namely that the each person should act to their own advantage, without regard for others. Given that there have been at least two proposed first principles for objective morality, there must be some value which Sam Harris holds which lead him to his choice. There simply is no innate property of the universe or human biology which can solve this problem. It is a matter of opinion.
Second is the problem of defining "well-being." There are so many values underlying any single determination of "well-being" that it would be difficult to identify them all. As a common example, we can examine the case of corporal punishment in child-rearing. Both sides of the spanking debate stake claim to the "well-being" of the child. How do we objectively parse out which approach really leads to greater well-being for the child? We have to rely on our own opinions to determine that.
Thirdly and finally, there is the interesting opinion that non-conscious creatures need not be the recipient of well-being, at least not as a first principle. We can further complicate this point by noting that consciousness does not have a definite scientific opinion and is therefore also the subject of opinion.
Objective systems of morality are not possible. I think the reason for this lies at the very heart of morality and ethics: they are a discipline which studies how people think the ideal is different from the real in society. If someone wants to articulate a how behavior ought to be different, it must be expressed via an opinion. And I think this problem is further exposed with the following question: if there is an objective (yet not merely descriptive) morality, why hasn't humanity found it, agreed upon it, and embraced it?
Empirical evidence, facts, logic, and reason are of course indispensable tools in morality. After all, how else could we tell if our actions were in line with our moral principles? How else would we be able to explore the implications of our morals for new areas of consideration? But facts and logic are ultimately just tools. They are not and can not be the building blocks of morality. This point is so obvious to me that I do not understand why such brilliant minds can miss it. Perhaps I am just deeply deceived, but I know that I have a lot of excellent philosophy on my side.