O que é vida? Parte II: A pobreza do darwinismo

sábado, dezembro 31, 2011

30 December 2011

What Is Life? Part II: The Poverty of Darwinism


In “Part I: The Problem of Agency,” I showed that our normative concepts (roughly, noncausal requirement, purpose, value, and meaning) are intimately related conceptually to one another and to the notion of agency.

Next, I showed that the concept of normative agency, thus defined, is properly applicable to even the most primitive forms of life—even single cells may be properly viewed as normative agents. Thus, conceptually speaking, agency appears to be an essential feature—probably theessential feature—of life itself.

And finally, I ended by asserting that the most reasonable explanation for these facts is that our concept of agency refers to a real phenomenon—agency is an objectively existing property of all organisms.

These claims may appear fantastic to most defenders—and even many critics—of the mainstream Darwinian view of life. Therefore, two more discussions will be required before my via media position between reductionism and theism may begin (I hope) to take on an air of plausibility.

First, I must show why the problem I am addressing—roughly, the place of normativity in the universe—has not already been solved by mainstream science. That is the topic of this column.

Second, I must offer at least some hint of a new direction for future research. Logically, it ought to be enough to point out the inadequacy of our current scientific worldview. But rhetorically, in order for my view to appear plausible, I need to give at least some positive indication of what a post-Darwinian scientific worldview might look like. So, that will be the topic of Part III.

Before proceeding, I would like to acknowledge that not everyone who broadly accepts the mainstream scientific story is a normative nihilist. In the first place, most biologists are probably content to pay lip service to the Darwinian metaphysics without giving too much thought to what it actually entails. They just go about their business—in the laboratory and around the dinner table—with the vague idea that somehow the theory of natural selection makes sense of it all. My remarks are not really addressed to such folks, who are simply unconcerned, professionally or personally, with philosophy or consistency between the different aspects of their lives and experience.

Rather, my remarks here are addressed to those—be they naturalistic philosophers or scientists who make grandiose metaphysical claims for Darwinism—who do concern themselves with the big picture. They do philosophy the honor of taking the problem of normativity seriously, but they do so by viewing our normative concepts as illusory—as referring to nothing real. They claim that the theory of natural selection—supplemented by physics, chemistry, and molecular biology—provides an empirically complete and logically coherent explanation for all the data of biology, and that our normative concepts simply fail to refer to anything objectively existing. These are the folks to whom this column is mainly addressed.

But there is another group, as well, who more or less accept the mainstream scientific worldview at face value, but who balk at its materialistic and reductionist implications. I am thinking of those philosophers who take a basically dualistic approach to the problem, arguing that the domain of normativity—and the realm of human subjective experience, more generally—has its own separate reality, which natural science is simply incompetent to address. There are both theistic and naturalistic versions of this position.

I admit that the naturalistic forms of dualism (broadly, Kantian and phenomenological approaches) are in many ways attractive.(1) But ultimately I reject them, for two reasons. First, the metaphysical division they postulate seems an arbitrary limitation on our search for understanding. Unification—showing how the various parts of our experience cohere—is the very essence of understanding, and there seems no a priori reason why the problems of normativity and agency should be sealed off from empirical inquiry. Of course, it remains for me to show how “unification” can be pursued in a nonreductionist spirit (see Part III).

The other reason why I feel the dualistic approach ought to be rejected is pragmatic. Some philosophers may see in dualism an irenic solution to our problem, but scientists are not likely to go along with them. And, unfortunately, wherever the scientists lead, they tend to drag the rest of us by the nose along with them. The materialist and reductionist vision of the world favored by consistent Darwinists—what I have been calling “value” or “normative” nihilism—is gaining ground with the public at an alarming rate. If it isn’t effectively challenged, our very humanity may be at risk. The most effective way to mount such a challenge is to demonstrate the conceptual and empirical bankruptcy of the Darwinian reductionist worldview.

Let us now turn, then, to this pressing task.

* * *

By “Darwinism,” I mean the claim that the theory of natural selection provides a logically coherent and empirically adequate explanatory framework that is capable of accounting for all biological phenomena in purely mechanistic terms.

Note that challenging this reductionist explanatory framework in no way calls evolution (common descent) into question. It simply raises the question whether our current understanding of life—and so of evolution—makes sense.(2)

It is sometimes hard for those who have not thought very much about these matters to realize what a radical claim Darwinism, so defined, makes. The claim is that our concepts of purpose, value, and meaning—and many other related concepts—literally refer to nothing. Nothing exists in reality corresponding to these ideas. All that really exists is just matter, energy, physical forces, and the principle of natural selection. And with these scientific concepts, we are supposed to be able to give a complete account of everything there is to know about living systems, including ourselves.

So, let’s see if this is true—if it is really the case that the theory of natural selection, together with molecular biology and the rest, provides us with a conceptually and empirically adequate account of biological reality.

The first thing to observe is that the Darwinian explanatory framework cannot do everything it claims to do unless it strictly avoids invoking any normative concepts. That means it may neither appeal to any normative concepts explicity, nor tacitly presuppose any such concepts. If it does explicitly invoke or tacitly assume such concepts, then—at best—it is begging the question of normativity, or—at worst—it is simply incoherent.

Now, it is a striking fact that actual biological practice is replete with normative terminology. You can hardly listen to a lecture in a biology class—you can scarcely find a single page in a biology paper or textbook—that does not violate this prohibition on normative language.

At every step of the way, biology demands consideration of functions (a variety of purpose), requirements, needs, and the reasons why things happen. Everything that happens in organisms seems to have an evaluative dimension as well: We speak constantly of success and failure, good and bad, better and worse, correct and incorrect, etc.

Then, there is the whole range of intentional discourse that has entered biology over the past couple of generations. Biologists cannot get along nowadays without using intentional terms like sign, signal, message, messenger, code, representation, transcription, translation, proofreading, editing, and many others, all borrowed from the ordinary vocabulary for discussing various aspects of human language use.(3)

In short, it appears impossible to discuss biological systems intelligibly for any length of time using only the vocabulary of the natural sciences. Normative vocabulary is simply essential to biological discourse—whether in technical language or in everyday speech. It seems that we have no choice but to employ normative concepts in order to describe living things adequately, and yet we have no need of them to describe the nonliving world.

Presumably, this is no mere coincidence, but rather is due to the fact that living systems are physically quite different from nonliving systems. The fact that we must make use of normative concepts in the one case, but not in the other, provides us with an important clue about the real nature of living systems, if only we choose to pursue it.

Now, the Darwinist will be unimpressed by all of this. He will say that the difference in our way of thinking and speaking about living things is simply an artifact of our cognitive limitations. He cannot very well deny that biological discourse is shot-through with normative terminology, but he can and will deny that we ought to draw any deep metaphysical conclusions from this fact. Rather, he will blithely brush the problem away, saying that the normative language of biology is merely a convenient way of speaking—a façon de parler—and that no particular importance should be attached to it. It is useful in practice, as a heuristic device, but in principle it is not necessary.

Why is it not necessary? Because according to the Darwinist, in principle we know how to substitute the language of the physical sciences for the normative terminology. That is, the Darwinist claims we can take any particular normative term and translate it into terms of physics and chemistry—with the help of the theory of natural selection—without loss of explanatory power.

This, then, is the crucial claim that we must evaluate. Can the Darwinist really use natural selection to rid his theoretical framework of explicit and implicit reliance upon normative concepts? If he can, then he wins, and we must admit that our entire human spiritual world of purpose, value, and meaning is just a tissue of illusion. If he cannot, then he loses, and natural selection goes out the window as the foundation for the modern scientific worldview.

Normative nihilism, yes or no? The intellectual stakes could hardly be higher.

To save space, I am going to assume the reader is familiar with the basics of the theory of natural selection, and go straight to the heart of the Darwinist’s reductionist strategy. The fundamental idea—the essence of Darwinism as a metaphysical system—is that all the appearance of normativity and agency in living things can be explained away in two steps:

(1) We assume that the cell is a machine—all its operations may explained through local physical interactions, and there is no global constraint on the local interactions. Let’s call this the mechanical principle.

(2) The functional coordination of the parts comes about purely through the process of natural selection—random variation and selective retention. Let’s call this theselection principle.


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