Nagel's Neoaristotelian Teleology

In Chapter 4, Section 6 of Mind and Cosmos, Thomas Nagel adds a fourth kind of explanation for the existence of organisms, consciousness, reason, and value.  The first three I have considered in previous posts: chance, non-intentional biasing, and intentional biasing. 

Nagel considers all three to be inadequate.  He accepts the apparent consensus that the appearance of the original, proto-biological self-replicators cannot be explained by random processes.  He accepts Robert White’s argument that non-intentional biasing is not indicated because, while it can explain non-random patterns, it cannot explain a bias “towards the marvelous.”  This is to say that non-intentional biasing is no more likely to produce creatures or traits of creatures that look designed than mere chance.  Finally, he rejects intentional biasing in large part because he is an atheist. 

So what is left?  Nagel proposes a naturalistic teleology

that is distinct from all three of the other candidate explanations: chance, creationism, and directionless physical law. 

What does a “naturalistic teleology” mean?  When we try to understand any natural event, we look for ways in which the initial state of the system limits subsequent states.  A beaker of water can be frozen or heated to a boil, but not transformed into gold.  Lava under the earth can produce a volcano, but not Godzilla. 

Given any initial state of a system, some subsequent states are more likely than others.  It is rare, but not unprecedented, for mammalian evolution to move toward the development of wings and flight.  Some mammals returned to the sea and began to look a lot like fish; however, they did not develop gills.  This is what Daniel Dennett meant when he talked about “design space”.  At any point in the history of life on earth, a range of future organisms is possible.  As environments change, evolution will explore the possibilities in design space.  A population of lizards may change color to blend in better with new local vegetation, but the lizards will not acquire the power of genuine invisibility. 

Nagel proposes that the laws of physics underlying the appearance of life are biased towards “the formation of more complex systems”. 

Teleological laws would assign higher probability to steps on paths in state space that have a higher velocity toward certain outcomes. 

In other words, there is something in inorganic matter that is biased toward the development of something like human beings.  It smoothed the path toward the appearance of the Ur-replicators, and then toward the development of genuine organisms.  It has operated in evolution up to the appearance of philosophers. 

All I would add at this point is that Nagel has become an Aristotelian, if not a Platonist.  The Socratics clearly believed in an embedded teleology.  It is not, or not so much, that some God intervenes to govern the course of organic development.  It is that mind is already present in the forces that mold living things. 

That is a shockingly bold proposal.  How it can be maintained and/or squared with a scientific scheme seems to me to be a challenging question.  I don’t know if we can make sense of such an embedded teleology without a divine intention biasing the cosmos; however, if we forget about that question for a moment, this is a plausible picture of the history of life on earth. 

Roger White on Origin of Life Explanations 2

Roger White distinguishes three types of phenomena, illustrated by “pebble patterns.” 

The Chancy Explanation: Pebbles scattered randomly on a sidewalk require no other explanation than chance. 

Unintentional Biasing: Pebbles arranged in order of diminishing size as they a near the shoreline. 

Intentional Biasing: Pebbles arranged in the shape of a fish (without legs). 

I altered the last one in a way that I hope will be amusing.  According to White, all but a few of those who write with expertise on the problem of the origin of life believe this phenomenon must fall into the second category.  Some natural forces must bias the Kosmos toward the emergence of life, just as the tides bias the pebbles toward a coherent pattern. 

The third explanation is ruled out as unscientific.  The first is ruled out because it is wildly implausible that the conditions upon which the emergence of self-replicators depends should have come about, in the time allotted, merely by chance.  Unintentional biasing must therefore be true by default. 

White argues that the reason that the origin of life is not at all like the unintentional biasing of pebbles by size on the beach. 

The numerous steps required for life to exist are quite unlike this. It is not a matter of the same event-type or property being instantiated many times without exception. The conditions required for the emergence of life have little at all in common.

Adding a bit to what White says, the emergence of life on earth seems to have been a single event (however long it took), not a repeated pattern. 

Why then are most scientists so reluctant to allow too much chance into their accounts of life’s emergence? I will offer a speculative diagnosis. The conviction that life couldn’t have arisen by chance is typically a gut reaction to the data, not a conclusion arrived at on the basis of a theory about when it is plausible to ascribe something to the work of chance.

What makes this event seem so implausible to so many is that it seems to suggest unmistakable evidence of design. 

Again adding to White, I would contrast the origin of life problem with the problem that Darwin addressed.  Why do so many different organisms exist, all of them more or less well adapted to their respective ecological niches?  That is a pattern that is persistent historically and geographically.  Natural selection then can be seen as the unintentional biasing mechanism analogous to the motion of water acting on the pebbles. 

Interestingly, unintentional biasing would be a much more likely explanation for the origin of self-replicators if Aristotle had been right about spontaneous generation.  If the emergence of living organisms from non-living matter under predictable conditions were a persistent feature of nature, as Aristotle, for understandable reasons, believed that it was, then unintentional biasing toward the emergence of life would be very likely indeed.  Of course, this is not the case. 

White makes a strong case that unintentional biasing in nature is not a well-grounded explanation for the origin of life.  That leaves chance and intentional (or intelligent) design.  I would suggest, however, that his dismissal of the gut reactions of so many scientists is premature.  To use one of his analogies, if a tornado picked up a pile of spare parts and assembled it into a working 747 airliner, no one would interpret this was the work of mere chance.  If even the simplest molecular self-replicators as well-designed as the airplane (which may be the case) and unintentional biasing is not a plausible interpretation of the former, then…

I am not making an argument for intelligent design here.  I am not particularly interested in it only because I don’t know what to do with it when thinking philosophically and scientifically about the phenomenon of life.  I do think that White’s argument could be turned almost as easily (perhaps just as easily) into an argument for intelligent design as for the origin of life by chance.  That fact may tell us something about the phenomenon.  If so, it would be unscientific to ignore it.  

The Origin of Life, Chance, and a Biased Kosmos

Tonight I read “Does Origins of Life Research Rest on a Mistake?” by Roger White (NOUS 41:3 (2007) 453–477).  Nagel refers to this paper and White refers back to conversations with Nagel.  It is a very interesting read. 

White challenges a basic assumption that is apparently shared by almost all of those scientists who are trying to explain the origin of life.  Darwinian theory does very well at explaining the emergence of more complex and varied forms of life from simpler forms.  It depends, however, on the existence of self-replicating molecules that can come under the influence of natural selection.  What can explain the origin of the self-replicators? 

White presents the alternatives with an elegant metaphor: the three pebble patterns. 

Pebble Pattern 1: Pebbles are scattered in a disorderly fashion as we typically find them on the sidewalk. 

Pebble Pattern 2: At the English seaside, pebbles cover the beach in descending order of size toward the shoreline

Pebble Pattern 3: The pebbles are arranged to form a stick figure with a smile on its face.

Pattern 1 requires no explanation other than chance.  Random forces acting on the initial state (the prior position of the pebbles) produced the current state.  Call this the chance explanation. 

Pattern 2 shows a coherent pattern that does call for an explanation that involves more than chance.  The action of wind and wave select out heavier and lighter pebbles and place them accordingly.  Unlike the previous example, where the resulting state is largely dependent on the initial position of the pebbles, in this example it doesn’t matter much how the pebbles were distributed initially.  The forces at work will move them toward the same arrangement.  White calls this “unintentional biasing”. 

Pattern 3 shows clear evidence of intentional biasing.  Anyone looking at the stick figure will assume that someone intentionally arranged it to make a picture. 

White informs us that almost all of the origin of life theorists reject the chance explanation for the origin of the proto-organic molecules from which all living organisms descended.  The reason is that the emergence of such molecules by chance seems absurdly improbable.

We require one kind of chemical to be present, plus another very different one , and yet another different one , and we require the absence of still other substances. Certain chemical reactions must take place, then others involving different ingredients and producing different outcomes. A wide variety of events that would undermine the whole process must fail to occur. The molecular parts required to make up the replication machinery come in various sizes and structures. And they are not arranged in anything like a simple repetitive pattern but rather each has a very unique position and role to play.

Add to that the fact that the window of time in which this had to take place seems woefully inadequate to those that have looked at the problem with expertise.  To appeal to a familiar metaphor, the emergence of self-replicating organisms in the history of this planet is about as plausible as an army of chimpanzees, randomly striking their keyboard, turning out a copy of Richard III before lunch. 

Neither can the origin of life theorists appeal to intentional biasing (which is to say, intelligent design) as that seems strictly outside the realm of science.  So they have to believe in some form of unintentional biasing.  Something in the nature of the planet (and hence of the Kosmos) was biased in favor of the emergence of life just the tides are biased in favor of a certain arrangement of pebbles. 

White does not indicate whether he accepts the view that the appearance of self-replicating chemicals was as improbable as I put it above.  He just points out that most theorists regard it as so. 

His thesis is that the only reason to reject the chance hypothesis is that life looks like something that was intentionally designed and that fact provides no reason to believe in any natural, unintentional biasing mechanisms.  If I win the lottery despite implausible odds, I may feel as though I had been somehow favored over chance; it makes no case that the lottery is biased, intentionally or otherwise. 

I suspect that White is inclined toward the chance hypothesis.  Those of us who cannot buy it are only lottery winner who cannot believe that in our own good luck.  If the consensus is correct that luck is an implausible explanation, then his reasoning points in the direction of intentional biasing.  That pushes my theometer a couple of clicks in the direction of yes.