Ed, sorry it has taken me so long to get back to you. All of May was taken up by final exam grading and then copy-editing and indexing my new book, due out in August, It Started with Copernicus (completely unabashed and self-serving plug). This is a response to your post of April 25, “A Second Exchange with Keith Parsons, Part I.”

I am very pleased to see how much agreement there is between us. You say that a crude divine command theory would posit a cosmic dictator, a Saddam Hussein writ large. I couldn’t have said it better.

I also hold that there are natural states of thriving or flourishing that constitute the (non-moral) good of organisms. As the Richard Dreyfus character says of the great white shark in Jaws, all such an organism does is swim, eat, and make little sharks. A shark that effectively swims, eats, and makes little sharks is living as well as a shark can live. For human beings, my conception of human flourishing is the same as Aristotle’s eudaimonia: Humans are living as best they can when they think and decide rationally while enjoying fruitful and rewarding interactions with other human beings and while enjoying health and a modicum of material prosperity.

You and I both agree that moral good arises from natural, non-moral good, but we disagree on the nature of the latter. You say that the natural good of an organism depends upon its intrinsic nature—the substantial form in scholastic terminology. I think that there is no such thing.

My understanding of Darwinism entails that “species” only has meaning when considered synchronically. Specific differences represent time-indexed arrangements in the economy of nature, the way that gene pools are sequestered at that given time. Considered diachronically, over geological time, there are no species, no permanent forms. After Darwin, we must regard all organic features as to a large extent plastic. Further, from a Darwinian perspective, the natural good of an organism depends not just on the organism but on the ambient environment. Change the environment and what used to be good for an organism becomes bad. It is good that we can breathe air, but if we lived in Kevin Costner’s Waterworld (yeech) having gills would be better. It appears that permanent, substantial, organic forms just cannot fit into this picture. Organic form is just a temporary solution to the challenges posed by a changing environment.

It is important here to note that the commitment of evolutionary biologists to the mutability of forms across time is not due to an a priori commitment to metaphysical naturalism. Pace Richard Lewontin, we need not say that “natural science” is a tautology. No, the evident plasticity of organic natures derives from our best scientific knowledge about how evolution occurs, i.e. how genomes change and how alleles spread through successive populations. Molecular and population genetics are the drivers here, not metaphysics. Put simply, the basic reason why evolutionary biologists do not countenance irreducible teleology is just that, so far as they can tell, it just is not there! All organic functionality appears explicable in terms of random variation and selection by the (temporarily) ambient environment. Tendency to retain organic form is due to stabilizing selection, not, so far as anyone can tell, a metaphysical principle. Further, over geological time there is, as Darwin said, a tendency for populations to diverge from their ancestors to an indefinite degree. In one hundred fifty million years you can go from the dinosaur to the hummingbird.

Of course, as you note, no empirical evidence can refute a metaphysical claim, though I think it can render it otiose. Intrinsic teleology might be there even though we cannot see it and have no need of it in our theories. Yet, Darwin was quite philosophically astute when he replied to Asa Gray—who suggested that variation might be divinely caused for ends that we cannot fathom—that to say that variation is planned but planned in a way that looks totally unplanned, is to utter a vacuity.

As you say, then, I reject non-reducible teleology, though I maintain that this rejection is not a metaphysical dictate, but is an inference from our best science. At the very least we can say, after Laplace, “I have no need of that hypothesis.” There is no more scientific need to postulate substantial forms than vital forces.

Can reducible teleology be sufficient to provide a basis for ethics? I say yes and you say no. You say that there can be no real non-reducible teleology, but only “as if,” metaphorical teleology if naturalism is true. I disagree. I think that there can be real yet reducible teleology. First, let me quote from a world-class expert on Aristotelian biology, my mentor at Pitt, Prof. James Lennox:

“Aristotle devotes two chapters of the Physics (II. 8,9) and most of the first chapter of Parts of Animals, I, to justifying his view that certain natural changes take place, and certain natural attributes exist for the sake of some end. Not only do these changes and things contribute to an end—they take place and exist in part because they contribute to an end (From “Teleology” in Keywords in Evolutionary Biology, edited by Evelyn Fox Keller and Elisabeth A. Lloyd).”

Does contemporary biology, even molecular biology, still employ such functional explanations, i.e. explanations of something in terms of the end it serves? Yes it does and always will, says no less an authority than Alex Rosenberg (The Structure of Biological Science, chapter 3). Now for Rosenberg, of course (and for me), such explanations are in principle reducible, i.e. given world enough and time we could, with immense worthless labor, substitute a staggeringly complex non-teleological explanation at the molecular level for a teleological explanation at a higher level. However, such in-principle reducibility of teleological explanations does not render them merely metaphorical or render the terms of such explanations into fictions. A reductionist auto mechanic might hold that the operation of a fuel injection system can be explained at the molecular level, but that does not mean that there are no fuel injection systems or that their purpose is not to achieve a mixture of air and gas favorable for combustion.

Finally, then, (since I am already over the 1000 word limit) I consider it a false dichotomy to say that derived teleology must either get its teleological nature from intrinsic teleology or must be only metaphorical “as if” teleology. This dichotomy overlooks the third option, namely, that a non-teleological process—the “blind watchmaker,” natural selection—can generate organic attributes that exist because they are teleological, i.e. they exist because they contribute to a certain end and that end serves to enhance the reproductive fitness of the organism. For instance, the formidable alligator snapping turtle has a peculiar vermiform tongue. Why? Because the wiggling of that worm-shaped tongue serves as a natural fishing lure, functioning to entice hapless fish into those waiting jaws. With a sudden snap the fish is gone, the turtle gets a meal, and a well-fed turtle lays more eggs. Mutatis mutandis, what is true for turtles is true for us!