Tuesday, December 18, 2012
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.