Wednesday, June 19, 2013
Addy Pross' Non-Reductionist Reductionism
To a man who makes shoes, the whole world is made of leather.
That proverb, Chinese in origin if I remember correctly, came to mind tonight as I read more of Addy Pross’ What is Life. This is one of those beautiful little books that bare the soul of a complex science to amateurs like me. Pross clearly intends to answer the question in a reductionist fashion. Biology, he dares to say at one point, is just another branch of chemistry. Well, the whole world is made of chemicals. Is biology really reducible to chemistry? No.
In chapter 4: ‘Stability and Instability’, Pross gives us a tour of basic chemistry. Chemical reactions move “downhill,” i.e., from states of higher free energy to states of lower free energy. Sometimes, I gather, they have to get over a “hump,” and in those cases a catalyst is required.
To employ my own analogy, an avalanche occurs when an unstable sheet of snow begins to slide downhill. The catalyst may have been some fool yodeling. The result is a ton of snow on top of a group of helpless skiers, at which point the situation is distressingly more stable than the original state.
Similarly, a mixture of hydrogen and oxygen gas is higher in energy than water. It requires a spark (the catalyst) to get the former to combine into the latter, but once the combination has happened water is relatively stable. Good thing, that. Two cheers for the second law of thermodynamics.
Pross then makes a distinction between two kinds of stability: static and dynamic. Water molecules are statically stable. Once formed, a molecule of water remains materially what it is pretty much forever. A river, by contrast, is dynamically stable. The Thames River has been flowing, he tells us, for around thirty million years—longer than there has been an England. Yet the water in it is constantly renewed. As Heraclitus famously observed, you can’t step in the same river twice.
Self-replicating molecules (e.g., RNA) are capable of achieving dynamic stability. They form and decay by a constant exchange of basic building blocks. In one experiment, more robust RNA chains emerged from less robust versions. All populations of living organisms achieve some measure of dynamic stability. Cyanobacteria have been in business for more than two billion years! That makes geography look short sighted.
Pross goes all in by arguing that the stability achieved by such populations of organisms is more than analogous to the chemical stability governed by the second law of thermodynamics (which just states that isolated molecular systems always go from less stable to more stable states). He proposes a version of the second law for dynamic stability:
Replicating chemical systems will tend to be transformed from (dynamically) kinetically less stable to (dynamically) kinetically more stable.
So the elegant symmetry of chemical reactions is reproduced at the level of organic systems. Thus is biology consumed by chemistry.
Color me underwhelmed. Granted, I am only half way through the book; however, it seems to me that dynamic stability just isn’t another version of static stability. It is a whole ‘nuther’ animal, as we would say down South. To be sure, everything going on in living organisms has to obey the laws of thermodynamics. Organisms, however, obey rules that are not derived from those chemical laws. The stability of populations in a given ecosystem incorporates chemical stability but it is not reducible to the laws of chemistry. Biology is a more comprehensive science than chemistry. Sorry.
Nonetheless, I am very grateful to Pross for this argument. I think that he has conceded all the ground he hoped to occupy. I also think that his dynamic stability is pretty much what Aristotle was aiming at in his treatment of the soul. Aristotle’s soul is precisely the communication of organic form over time by means of a constant exchange of matter (and I would add, energy) with the outside world. Aristotle was a vehement opponent of reductionism. Pross’ reductionism isn’t reductionism at all, thus confirming the Philosopher’s point.