A young friend recently published a paper (You can find it via the Table of Contents here) in the journal Tolle Lege in which he offered a critique of the late Philippa Foot's attempt to derive ethical norms in the context of a naturalistic (atheistic) worldview.
His paper is well-conceived, and in writing to commend him for his work I added some thoughts of my own on the subject. I opined that it seems to me that any ethic, naturalistic or otherwise, has to accomplish three things in order to be credible:
1. It has to avoid David Hume's Is/Ought fallacy (sometimes called, appropriately enough, the naturalistic fallacy). In other words, as the great Scottish skeptic taught us, we cannot say that because things are a certain way that therefore they ought to be that way. Human beings have certain moral feelings, but we cannot argue that those sentiments are right just because we have them.
After all, we also have feelings of hatred, selfishness, avarice, violence, etc., but most of us don't think that behaving in accord with those feelings would be morally proper.
2. It has to explain the sense in which the idea of a moral wrong can be meaningful if there's no ultimate accountability for one's behavior. In other words, if a tyrant is rewarded with great wealth and power and dies old and content in his bed, in what sense was the suffering he caused others wrong? It seems to me that "wrong" as an ontic entity can only exist if there also exists ultimate justice and inevitable accountability in the cosmos, and those can only exist if God exists and naturalism is false.
3. Related to #2 is the problem of explaining what we mean when we say that "X is wrong." Is X wrong merely because other people don't like it, as Hume suggested, or is it wrong because it somehow violates the moral order of the cosmos? If it's the former then "X is wrong" is merely a subjective expression of personal preference or an emotive reaction to something that's personally repugnant, like exclaiming "ugh!"
On the other hand, if X is wrong because it offends against the moral order of the cosmos, an order that somehow mysteriously imposes obligations upon us, then the naturalist has to explain how an impersonal, purely material world can levy such obligations or possess any kind of "moral order" in the first place.
It's hard to see how a naturalistic ethic, based as it is on the assumption that the physical universe is all there is and that human beings are just an ephemeral collection of atoms and molecules, can muster the metaphysical resources to meet any of these tests.
That being so, it follows that when naturalists make moral judgments or use moral language, they're doing nothing more than expressing their own approbation or revulsion, like saying "yummy" at being presented with a dish of one's favorite ice cream, or shuddering at the suggestion of mixing it with tuna fish.
That so few naturalists realize the utter subjectivity, arbitrariness and vacuity of their moral views, whatever those views happen to be, is an interesting sociological phenomenon, as is the fact that so few others ever seem to call them on it.
