Wednesday, June 16

Evolution, Imagination, and Statistics


Skepticism is the chastity of the intellect, and it is shameful to surrender it too soon or to the first comer: there is nobility in preserving it coolly and proudly through long youth, until at last, in the ripeness of instinct and discretion, it can be safely exchanged for fidelity and happiness. -- George Santayana

Several times I have watched the video of the debate between Bill “The Science Guy” Nye and Ken Ham on evolution and intelligent design.  A better example of two people talking past one another could only be found by climbing into a time machine and going back to the 17th century to eavesdrop on the trial of Galileo.  Both Mr. Nye, who should have known better, and Mr. Ham managed to lay down a smokescreen of invidious rhetoric so dense as to overly complicate a question that is dispositive of the entire debate between purely naturalistic science and theistic science.  (By “theistic science”, I include not only theistic evolution, but also all accounts of the natural order, in any scientific discipline, that seek to invoke God as an essential explanatory construct.)  That question, in its most straightforward form, is simply this:  what, if any, is the role of God in the process of formulating and substantiating scientific accounts of natural phenomena?  My own position is quite simple:  there isn’t one.  God may be, most likely is, pragmatically useful as a means of underwriting moral judgments (though I would argue God is not essential even for that purpose, though that is a subject for another rant), and for many people is an essential element of their emotional, psychological, axiological, and “existential” ballast.  But as an element of scientific explanation, God has no role, and has not had one for perhaps as long as 500 years, certainly not since at least the middle 1800s (i.e., the time of Charles Darwin and Alfred Russell Wallace). The reason God is superfluous for scientific purposes is because of two questions – which are very arguably the same question – that positing God and intelligent design are insufficient to answer.

Question 1What aspect of evolution, or any other natural phenomenon, is explained which would be unexplainable if one did not postulate God?

This question alone would make a good yardstick to use, at least in a qualitative sense, in measuring the progress of purely naturalistic science.  Several thousand years ago, the answer would have been “Well … just about everything, because God is necessary to explain almost everything”.  But over the intervening millennia, one by one, natural phenomena previously held to be explainable only by hypothesizing some kind of Divine intervention came to be accounted for by purely naturalistic means. (In historical theology, this ever-shrinking sphere of the usefulness of God in science is colloquially known as the "God of the gaps":  as the "gaps" shrink, so does God's role in science.) Perhaps the very last bastion, certainly one of the last such, to hold out against a purely naturalistic, materialistic, cause-and-effect explanation is the appearance of species in general – and of the human species homo sapiens sapiens in particular.  The rest of the natural order may be susceptible to such purely naturalistic explanations -- so the pre-Darwinian belief went -- but surely the Divinely ordained Crown of the natural order comprises human beings.  Around 1600, Shakespeare’s Hamlet articulated this view:

What a piece of work is a man! How noble in reason, how infinite in faculty! In form and moving how express and admirable! In action how like an Angel! in apprehension how like a god! The beauty of the world! The paragon of animals!

But in 1859, the first edition of Darwin’s Origin of Species was published, and then it became possible to relate to the second part of Hamlet’s vaunting speech:

NPG Ax17797,Charles Robert Darwin,by; after London Stereoscopic & Photographic Company; Ernest Edwards

And yet to me, what is this quintessence of dust? Man delights not me; no, nor Woman neither; though by your smiling you seem to say so.

So it turned out that God was not necessary to account for the appearance of human beings any more than to account for that of lions and tigers and bears.  Oh my!

I believe it is this gnawing sense of the last redoubt of theistic science having fallen that, no doubt for the most part unconsciously, continues to make Darwinian evolution so viscerally repugnant to conservative evangelical, especially fundamentalist, religious people, more so than even the equally materialistic, cause-and-effect account of the Big Bang.  The Big Bang pertains “merely” to the origin of the universe.  Evolution, however, pertains to the origin of us.  It is very easy to view the former on an abstract level, not least because the Big Bang occurred about 13.7 billion years ago.  But the human species is – in other words, we ourselves are – much more difficult to view with such clinical detachment.  Consequently, many people take evolution personally.  I may be indifferent, say, to the Big Bang's account of where the relative abundance of hydrogen and helium comes from.  But I am anything but indifferent to the evolutionary account of where I come from!

So the very fact that current evolutionary theory is so successful on so many levels, from the level of the evolution and extinction of entire species and webs of related species, to the molecular level of genetics, and the fact that it achieves this success with no recourse to intelligence, purpose, Divine ordination, etc., etc., renders it threatening for reasons quite unconnected with its strictly scientific adequacy as an explanatory structure.  From a scientific standpoint strictly of explanatory adequacy understood in terms of material, formal, and efficient causes, there is simply nothing left for God to do.

Question 2What collection of data would be inconsistent with the hypothesis "God did it that way"?

In other words, Is a theistic account of natural phenomena falsifiable?  I can hypothesize that all crows are black – all crows without exception.  This is, at least in principle, falsifiable:  all I have to do is find a single – just one will do – white crow … actually, any non-black crow.  Anti-evolutionists often argue that Darwinian evolution is likewise non-falsifiable.  But if the fossil record were found to contain a single instance of a more advanced species embedded in the same geological strata as less-advanced relatives – e.g., a single homo sapiens sapiens skeleton embedded in strata from a geological epoch previously thought to represent only some proto-hominid ancestors of modern humans – then the game would indeed be up with evolution.  But the only possible examples of such displacement have been found instead, upon closer examination, to be instances of relatively modern forms having been stratigraphically mixed with early types because of geological upheavals.  Arguments about “irreducible complexity” founder for similar reasons:  the classical example is the eye, earlier versions of which, contra the argument from "irreducible complexity,"  had survival value for the earlier organisms that possessed them.  (The eye is an even better example because evolutionary biologists have determined that the eye evolved independently in several species:  anything so "irreducibly complex" should not be so relatively easy to merely "copy and paste".) But suppose modern and early forms of human beings were found intermixed, and that, for whatever reason, no stratigraphic explanation were available.  Then the theistic evolutionist could always reply “Well, that’s just the way God did it” – the same potential theistic explanation for the absence of intermixing in the fossil record. Analogous remarks hold for “irreducible complexity”:  the absence as well as the presence of intermediate forms of organs is equally amenable to the “that’s-the-way-God-did-it” rationalization.  The fact that a theory is falsifiable means that it explains something, some discrete, determinate phenomenon, i.e., that things are this way, and not that way.  A theory that is not falsifiable explains both this and that promiscuously and indifferently. In fact, a non-falsifiable theory explains this and not-this equally well. So a theory that is not falsifiable explains nothing – because it can explain everything, even outright contradictions. A non-falsifiable theory is an epistemological harlot:  "faithful" to any man indiscriminately.  So the answer to Question #2 would be There is no collection of data that would be inconsistent, even in principle, with theistic science – theistic evolution or anything else.

A common response among advocates of theistic science – I also noticed this repeatedly in the Nye-Ham debate – is recourse to the human imagination via statistical arguments, though the imagination part of the argument is usually left implicit.  The argument goes something like this:  “What are the chances that anything as complex as, say, the human eye could evolve from the purely random process of natural selection, even given eons of geological time?”  The conclusion is that randomness alone, together with matter and causality, are insufficient to account for the elegant architecture of the human eye.  Therefore, intentionality, and by implication a Designer, are necessary.  But as Richard Dawkins and Daniel Dennett argue, the latter exhaustively and to the point of exhaustion, in The God Delusion and Darwin’s Dangerous Idea, respectively, natural selection is anything but random.   Given a set of “initial conditions” of natural law applicable to the universe as a whole, and a set of “boundary conditions” applicable to a particular environment at a particular time, the set of organisms that can arise can vary only within very strict limits.  There is a reason why bats are practically blind but have almost preternaturally keen hearing – and a “sonar system” to use with the latter for navigating in the dark. This consequence is anything but random.  Besides, what does a sheer lack of randomness prove?  If the complete letters and collected works of Fyodor Dostoyevsky – everything he ever wrote, from laundry lists to The Brothers Karamazov -- were published without a single error, with not a single letter or punctuation mark out of place, would that perfection be evidence of Divine origin?  Probably not.  Of course, we have a hard time imagining the elegant structure of the human brain, eye, immune system, etc., arising from purely natural phenomena!  But then, we have a hard time imagining that the nearest star outside our solar system is approximately 24 trillion miles away, or that a gamma-ray burst would be capable of sterilizing the surface of the earth from a distance of 6 thousand light-years, or that a thimble-full of neutron-star matter typically weighs as much as the aircraft supercarrier Ronald Reagan.  As the great British chemist J. B. S. Haldane is said to have remarked once “The universe is not only stranger than we imagine, it is stranger than we can imagine”.  Imagination is a wonderful place to begin science.  But it is a very unreliable place to end it.

In a certain sense, the contemporary debate about American students’ competency in science is urgent, and yet in another sense, it is misplaced.  In that latter sense, it “majors” on the “minors”. Yes, it would be nice if more Americans understood why the boiling point of water decreases as one’s altitude increases, etc.  Yes, it would be nice if more Americans understood that “global warming” does not mean that the temperature of every square millimeter of the earth’s surface is becoming uniformly warmer at the same rate.  But beyond familiarity with particular, discrete scientific facts and scientific principles, there is an even more serious need for better understanding of what science itself is and does, and what does – and does not – constitute sound scientific argument and scientific evidence.  This need was all too evident in the arguments advanced by Ken Ham in his debate with Nye.  Intuition, imagination, and faith are useful, even indispensable, in art, religion, and even in the appreciation of science.  (Albert Einstein held these abilities in great esteem, as witness his famous quote about the importance of a sense of wonder in science.) But the doing of science requires at least a more discursive working knowledge of evidentiary rules and of what inferences are warranted and which are not. Above all, it requires a skeptic’s willingness to follow a line of reasoning, even when -- or especially when -- doing so leads one away from long-cherished beliefs.

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