James Barham at Best Schools ‘fesses up #IV: The theory of natural selection is wholly inadequate to deal with the idea of purpose
|March 29, 2012||Posted by News under Philosophy, Intelligent Design, Darwinism|
Barham, the philosopher who runs The Best Schools, got collared by friends recently, and had to answer some questions. Like, why is he an atheist but not a Darwinist? So in our continuing series, we asked,
UD: Wouldn’t a mainstream biologist simply say that the neo-Darwinian theory of evolution has demonstrated once and for all that teleology (purpose) and normativity are illusions, and that all there are, are negative feedback systems put into place by random genetic variation and natural selection?
JB: In a word, no.
Here is another way of looking at the problem that can help us to see why the theory of natural selection is wholly inadequtae to deal with this issue.
I spoke a moment ago of the “equivocation” at the heart of modern biology? What exactly did I mean by that? It will be helpful to analyze this in a bit more detail.
The equivocation consists in blurring the distinction between two categories of events that do have a superficial similarity, but which must be rigorously distinguished if we ever wish to get at the heart of the problem of normative agency, which I am convinced lies in the deeper reason for the superficial similarity.
The superficial similarity is between the seeming “efficiency” with which all physical systems behave in the nonliving world and the “efficiency” already discussed with which most or all living systems act.
As an example of the first kind of case, we may take the fact that light travels in straight lines in uniform media.
It seems intuitively obvious that this is somehow related to the fact that a straight line is the shortest distance between two points, just as Diogenes’s donkey knew.
Moreover, light is refracted at interfaces between two media with different indices of refraction according to the formula:
The ratio of the sines of the angles of incidence and refraction at the interface between the two media = the inverse of the ratio of the indices of refraction of the two media.
We call this Snell’s Law after a seventeenth-century Dutch mathematician (though the relation was first discovered in Baghdad in the tenth century). The mathematical form of Snell’s Law is explained qualitatively by Fermat’s Principle, which states that light travels by the path which takes the least time.
However, it is not only light that travels in straight lines. Falling bodies and billiard balls on a table do so, as well. Newton generalized this fact in his First Law of Motion: in a vacuum, moving bodies continue moving with uniform velocity in a straight line.
In the eighteenth century, Leibniz, Euler, and Maupertuis all arrived at versions of a principle that united Fermat’s Principle and Newton’s First Law. This was the Principle of Least Action, which states (in modern terms) that all physical objects move in such a way that the action (energy x time) is minimized. Since we are not concerned with the historical details here, let’s simplify matter by giving the principal credit to Maupertuis, who spoke about an “economy” principle and the minimization of “effort,” and wrote that “Nature is thrifty in all her actions.”
Now, it is indeed astounding—and too little remarked upon—that Maupertuis’s Least-Action Principle seems so similar to Ockham’s Razor (entities should not be multiplied beyond necessity). Our minds spontaneously work according to a kind of “parsimony” or “least-effort” principle, just like rays of light and bodies moving in a vacuum. A striking fact that is surely no mere coincidence!
On the other hand, is it reasonable to suppose that Ockham’s Razor can be simply reduced to Maupertuis’s Least-Action Principle? Well, why not? After all, everything must obey Maupertuis’s Principle (assuming it’s correct), must it not? So why not say that Ockham’s Razor just expresses the fact that all of the electrochemical events in our brains are all occurring in conformity with Maupertuis’s Principle?
But it is one thing to say that events are occurring in conformity with a principle, and it is something else to say they can be fully explained by the principle. Certainly, there is no reason to suppose that the Least-Action Principle is violated in the brain. But neither is it of much help in explaining how thinking occurs.
The problem is that brains are nonequilibrium systems, drawing power to this or that place as needed. This is precisely what fMRI images shows: The parts of the brain that light up under that imaging system are the ones with increased blood flow, due to increased energy needs.
But notice that now we have introduced the normative concept of need. Blood flow is being directed here and there according to need, so it is the thinking that is redirecting the blood flow, not the blood flow that is driving the thinking. This simple fact makes of mockery of any attempt to explain brain function by means of a direct application of physical principles.
Therefore, Ockham’s Razor cannot be explained by direct application of Maupertuis’s Least-Action Principle. And yet the puzzling similarity of the two principles remains.
What of that vast field of phenomena lying in between human thought and inanimate motion? Are the donkey’s and Physarum’s actions more akin to Ockham’s Razor or to Maupertuis’s Least-Action Principle? Well, clearly everything we said about the brain’s functioning applies equally well to the donkey and to Physarum. They are not simply minimizing free energy any more than my brain is as I write this.
This suggests there is a deep chasm in nature, and that all of biology lies on the Ockham’s Razor side, while the inanimate part of the universe lies on the Maupertuis’s Least-Action side. This may be difficult to see initially, because Ockham’s Razor is a rule of thumb regarding explanation; it is not expressed in the form of a law of nature. And we don’t imagine that either the donkey or Physarum is consciously reflecting on the best way to proceed.
However, Ockham’s Razor is about efficiency in the sense of using the best or most appropriate means to arrive at an end. It is teleological to the core. In this respect, the rule of thumb for the proper working of the human mind also captures an important principle at work prerationally, or “instinctively, throughout all of the living world. Thus, Ockham’s Razor may be generalized to ”instrumenta non sunt multiplicanda praeter necessitatem” (means should not be multiplied beyond necessity).
Throughout biology, we remain in the realm of the Least-Action Principle so long as we are looking at individual physical or chemical interactions—between two molecules, protein folding, etc. But as soon as we invoke the purposive coordination of such interactions, we step out of the realm of the Least-Action Principle entirely and into the realm of Ockham’s Razor.
Now, to all of this, the Darwinist will no doubt say: “What’s the problem? Natural selection explains the appearance of purpose in nature. There’s random variation and the variants that happen by accident to be more efficient (“fitter”) are the ones that survive.”
But this is utterly superficial and question-begging. It simply assumes that teleological efficiency will be hit upon, given enough time, while the whole question is how it is possible for physical systems to make the transition from the Maupertuis regime to the Ockham regime, in the first place.
Next: Another perspective that is too often overlooked.
See also: Biology (like the social sciences) is guilty of massive and systematic equivocation about normative concepts