Review: Signature in The Cell

I highly recommend Steven Meyers's book Signature in the Cell. Nevertheless, in this post I'm going to focus on a aspect of his argument that seems to be a failure.

Setting aside the question of how life evolved, Meyers focuses on the origin of life. He shows how even the simplest known living things have an extremely complex teleology: they appear to be designed. Darwinian natural selection cannot explain this apparent design because for natural selection to get off the ground, there must already be a living (self-reproducing) system in existence. Meyers points to the interdependence of, on the one hand, the proteins that act as machines to perform the functions maintaining an organism's life, and, on the other hand, the DNA and RNA molecules that contain the information without which those proteins cannot be constructed. He demonstrates the implausibility of the RNA-world hypothesis, and of metabolism-first alternatives. He claims that the hypothesis of a designer provides the best explanation for the apparent design in biology. And he says that this is a properly scientific inference, which takes the same form as inferences in geology and other sciences that study the past, for it appeals to the vera causa criterion championed by Darwin himself: the best explanation for ancient events should appeal to causes now known to be in operation. Minds are the only things now known to be capable of originating complex teleology (i.e., apparent design). And since other possible explanations are either unavailable before the origin of life (natural selection) or poor explanations (chance, necessity, or combinations thereof), the theory of intelligent design (henceforth ID) should be accepted on scientific grounds as the best explanation for apparent design in biology.

Meyers has consistently distinguished ID from any religious or philosophical implications that might be drawn from it. It is analogous, in his view, to the big-bang theory: the old steady-state universe was a more intellectually comfortable home for an atheist; the big-bang theory seems to point in the direction of a first cause that transcends the physical world. But when one makes this inference to a first cause (whether justified or not) one has stepped outside of science. But the fact (if it is a fact) that big-bang cosmology entails, or suggests, something like the existence of God, does not make the big-bang theory itself non-scientific. Similarly, the design hypothesis is a scientific inference from the empirical evidence. It does not seek to identify the nature of the designer. It only postulates that some mind is, or some minds are, responsible for the very complex teleology that is present in all known living things. As far as the ID theory goes, those minds could be physically embodied, like our own minds. If that seems implausible, then the ID theory might seem to point to a transcendent designer, as the big-bang theory might seem to point to an ex-nihilo creator; but the fact that that inference from the ID theory is beyond science does not make the inference to ID non-scientific.

Now, my own view is that science and philosophy overlap that philosophical assumptions are equally present in evaluating the evidence for both Darwinism and ID, and that teleological and cosmological arguments for God's existence, and their rebuttals, can be legitimately called scientific arguments. But for this blog post, I am going to assume, arguendo, that a truly scientific inference can be distinguished from one that goes beyond science. And I aim to demonstrate that ID cannot be a good inference if it is of a purely scientific nature.



Let us imagine a race of aliens who have developed science to about the same level we have, but who, unlike us, have no history of religious belief or philosophical speculation. They neither believe nor disbelieve in God. They've never even heard of the concept of God. They are prosaic engineers, interested only in tractable, well-defined questions, and inclined to shrug off any deeper questions that cannot be answered by scientific methods.

Being the good engineers that they are, they easily recognize the complex teleology in even the simplest living things. And they understand that Darwinian explanations of this apparent design are inaccessible in a pre-biotic era. Suppose one of them suggest the obvious abductive inference: life seems to be designed because it was designed. The first question I expect his colleagues will ask about that postulated intelligent designer is:

Was it alive?

For those of a scientific outlook, this is a very pressing question. All the intelligent beings we know about are alive, and surely a non-living thing could not be intelligent. Our discoveries about brain function have only confirmed what common sense already tells us: a rock or a cloud or a star or anything like that could not be intelligent. Only a living thing could. And since obviously a living thing could not exist before the origin of life, the ID theory is a non-starter.

How might our protagonist respond? Perhaps by saying this:

To be sure, a rock or a star couldn't be intelligent. But that only shows that a non-living intelligence would have to be more like a living thing than those things are. It doesn't show that it would have to be fully alive.

Or he might say what perhaps amounts to the same thing,

To be sure, an intelligent designer would have to be alive in some sense. But it could have a biology very different from the cellular-RNA-protein functionality we are familiar with. Our questions about the "origin of life" are really about the origin of life as we know it. And life as we know it might well have been designed by a life form of an entirely different sort.

But his colleagues will surely point out that even a non-chemically based life form must have an origin. It could not be eternal as Aristotle thought living species were: Our knowledge of the big bang rules that out. And if this exotic life form is to have ideas and the power to physically implement them, it would have to be quite complex; but this complexity is the very thing that makes it seem impossible for our kind of life to have been caused by mindless forces. So the postulation of an exotic life form doesn't accomplish anything in terms of explanation: therefore it can't function as a best explanation for apparent design in biology.

Suppose our protagonist were to point out that

We can't assume that the physical world is all there is. We're supposed to be non-committal about such things. For all we know there might be a transcendent mind, which needn't exhibit any kind of complex physical arrangement of its parts, so it could function as an explanation for the complexity of life as we know it. I'm not claiming to know that there is such a being. I'm only saying that your objection to my theory seems to presuppose that there couldn't be, which is an illegitimate assumption. As long as we have not ruled out the possibility of such a transcendent mind, we can still affirm that the evidence of design in biology entails the existence of some kind of pre-biotic intelligent designer.

Not (his colleagues will say) if that entailment is supposed to proceed by scientific abductive reasoning. If ID is to be regarded as the best explanation, scientifically speaking, for the apparent design in biology, it will be because that hypothesis gives the best fit with what we know about the causal structure of the world. That's the point of the vera causa criterion Meyers makes so much of. But the ID hypothesis is either a failure as an explanation (in the case of an immanent designer) or it explains only by appealing to something (a transcendent mind) whose causal powers operate in a wholly different manner from those we know of: its causal powers would not be due to its inhabiting a physical causal nexus alongside physical things, but to something else, perhaps some kind of metaphysical dependence of events in the physical world on that transcendent mind. To appeal to that kind of thing is not to appeal to causes now known to be in operation.

We cannot claim that a properly scientific inference to the best explanation tells us that some kind of mind designed biotic life when we can see that any mind operating according to causal principles now known to be in operation would not be a good explanation for the apparent design in biology.

Notice that this argument does not require any physicalist assumptions about the nature of mind. Our alien scientists have no opinion on whether human minds are non-physical. They have no opinion on whether there are any non-human minds. For all they know, minds might be purely physical. Or they might not. They just don't know. What they do know is that the way minds influence the physical world is, in all cases they know of, through a physical vehicle: the brain. Even our inner thoughts have brain activity underlying them, and if that brain activity is disrupted, the normal course of nature dictates a corresponding disruption of the mental activity.

While there are legitimate scientific arguments that appeal to minds, those arguments must be distinguished from philosophical arguments resting on theories about the nature or essence of mind. Scientific arguments ignore such controversies and rely only on what experience shows us about how mind-endowed creatures behave in the observable world. Minds are known to cause design operating through animal bodies via the brain. I grant that we might legitimately (scientifically) postulate an analogous intellect, operating in an analogous way, to explain design in biology: the vera causa criterion does not require that postulated ancient causes be exactly like modern causes in every respect: they can operate in analogous ways. But if we are forced to postulate a cause operating in a way wholly unlike any cause now known to be in operation (because a mental cause operating in ways analogous to those we know would be causally inadequate as an explanation of design in biology) then the mere fact that it is a mind we're postulating -- that its essence is the same as, or similar to, the essence of our minds -- does not give it any cache as a best explanation, so long as we're restricting ourselves to properly scientific reasoning. The only way an explanation can get such cache is by its similarity in its causal operation to what is already known to occur. And that is precisely what it cannot have.