Dear Princess ‘Ishka,
I have been recently in Munich for a conference on the relation between values and rationality (roughly). I took the opportunity to visit a dear friend of mine, M, with whom, as it sometimes happens, I had a discussion greater than the one within academic walls. We debated on the possibility of reducing scientific fields to more fundamental fields, and I hope to show how this also relates to the topic of the conference toward the end of this letter.
My current aim is to report the content of the conversation between me and M as honestly as possible, making an effort to explain his points as consistently as he did. However, I am biased in this report by the urge of clarifying my own ideas, to which I will eventually give more relevance. In real life, M and I came to some kind of true disagreement and I deem our discussion far from having been settled.
To put it briefly, we posed ourselves the following question: “Can chemistry, given appropriate tools of calculation, explain the Darwinian theory of biological evolution (DTBE for short) exhaustively?” He answered yes, I answered (and still answer) no. Before getting into the nitty gritty of the debate, let me point out a couple of things we didn’t disagree upon:
- Neither of us believes that DTBE has been so far reduced to any more fundamental theory.
- We both believe that there might be a theory more fundamental than DTBE, of which human beings don’t know anything about so far, that might explain biological evolution on a more fundamental level than the one of natural selection of biological organisms.
So, where’s the disagreement? M thinks that the theory, which could potentially explain DTBE, is chemistry, and the reason why the reduction hasn’t happened yet is twofold:
- It is unpractical: the explanation of biological organisms at the level of molecules would be just too complicated and organisms offer a useful simplification.
- Our instruments of calculation are not sophisticated enough to calculate the “translation” of DTBE into chemical language.
However, he thinks that this translation is possible in principle, whereas I deny that it is. His main argument is that the universe is made, without exception, of molecules (and atoms) and physical void and if we have a theory to explain molecules and their interactions, we have a theory for everything that takes place in the universe, DTBE’s objects included.
I do not deny that the universe consists of molecules and void. What I deny is that the laws governing the molecules and their interactions can say anything interesting about biological evolution. How then? I shall arrive at it by steps.
M and I believe that different sciences create their objects of inquiry for practical reasons (like developing useful categories, e.g. physical forces, molecules, living organisms, ecosystems, and so on) as for human cognitive limitations. We also agreed on the hierarchy of sciences: more fundamental ones, giving constrains to less fundamental ones. In a certain sense, biology depends on chemistry in a way that chemistry doesn’t depend on biology: biologists must have background knowledge of chemistry to enquire into their field, while chemists do not need biology. This is because chemistry imposes boundaries on biology, and offers a tool to falsify biological theories: if they are inconsistent with chemistry, they are false, and not the other way round, namely that chemistry is false. Why? Well, because the objects of chemistry are simpler and can be more easily treated with mathematics than the objects of biology (this was also a point of agreement).
But then, why can’t we just conclude that we have not calculated enough to reduce DTBE to chemistry? After all, chemistry is more fundamental, isn’t it?
Yes, chemistry is more fundamental, but the principle of evolution captures an aspect of reality that is new: it is a new mechanism with new laws determining new objects of enquiry. Nothing of what DTBE is about is made of magical stuff, exonerating from chemical existence. It is just that particular conformations of molecules obey laws that do not belong to chemistry in principle and chemistry can’t describe them because it is bound to molecules as its “unity of measurement”. These particular conformations of molecules, from viruses to plants and animals and us, can’t disobey chemical laws, they simply start obeying new laws that can’t contradict chemical of physical ones. Still, they are genuinely new.
The mainstream version of DTBE consists of two main principles: natural selection and genetic drift. Depending on the conformation of the environment, the traits of organisms determine their survival, and these traits are in turn determined by genes. Neither the environment, nor the traits or genes are exonerated from being made of molecules, it is just that their meaningful interaction is of no interest for chemistry as the study of molecules. This is not because it would be too boring to calculate such interactions in terms of chemical stuff. Rather, DTBE deals with concepts that are new (however constrained by the more fundamental chemical level), such as life and death, survival and extinction, replication and reproduction, and so on. These terms are not useful labels for more complicated chemical stuff: they do not make sense as chemical entities! In chemistry there are no such things as life and death, but constant interactions between molecules or clusters of molecules. Chemistry indeed explains everything of the molecular composition of genes and of their effects on the traits of organisms, but it doesn’t tell anything about the evolutionary meaning of those traits for the organisms in their “battle for survival”. The very concept of selection would disappear in an extremely complicated hodgepodge of molecules, but it wouldn’t be explained. Why? Well, because the question DTBE is asking is not “What is there in the universe when an antelope is hunted by a lioness, and how did the universe come to this point?” but rather “According to what laws did the antelope develop strong, jumping legs and the lioness powerful jaws?”. The question constrains already the meaning of the answer, in the sense that to answer the second question with an immense chemical formula would be to have misunderstood the question. The answer is not a chemical formula (although such a formula probably exists), it is the law of natural selection.
To better explain my point, I am going to employ two analogies.
Here’s the first one: A state has certain laws for its whole territory, for instance, that chemistry and biology must be taught in high schools. A province of this state can’t contradict the laws of the state. However, it can formulate new ones, insofar as they are consistent with the more fundamental ones of the state. For instance, it can say that biology and chemistry must be taught together by one single teacher per class. It can’t however legislate that no chemistry be taught, for that would contradict the law of the state. Suppose further, that there is a city within this province. This city is under the law that biology and chemistry must be taught and by one single teacher per class. However, nothing hinders that that teacher must wear a pink cape with blue dots. So the city legislates that chemistry and biology be taught by one single teacher per class, mandatorily wearing a pink cape with blue dots.
The laws of the state couldn’t predict what more specific policy the province would have adopted, let alone the city. This is not a matter of not calculating enough. The state has specific worries about what to teach the pupils at all, which are more fundamental worries than how many teachers are needed to fulfill the teaching at high school level. These, in turn, are more fundamental worries than the dress code to be adopted by such teachers. With more fundamental I only mean “constraining what is less fundamental”, but how on earth can we understand how many teachers we need to teach biology and chemistry from the law that biology and chemistry must be taught? These two laws are about different things, and the fact that one is more fundamental than the other in our technical sense, doesn’t mean at all that the less fundamental can be deduced with more calculation.
Going back to our point, saying that DTBE is reducible to chemical laws is like saying that there is a way to deduce what color of cape a teacher must wear, given that we know that only one teacher per class teaches certain subjects. That is absurd, because the two kinds of laws address different problems, some of which are more fundamental than (pose constrains to) others.
A second analogy requires a little bit more of imagination. Think about a net made of rope. This net is passed through by certain objects falling from above, which are precisely of the dimension of its holes. It is made in such a way, that nothing can distort its pattern: everything going through its holes is “screened” as something cubic or parallelepipedal. Some of these objects are however slimy, like little blobs and they pass through it, but could also change their form. Under a certain description, they are of the form required to pass through the net, but there is something important to them that the net can’t capture: their sliminess or their “blobbiness”. Still, these blobs can’t distort the net, and they are screened just as solid cubes and parallelepipeds. In order to understand what is peculiar about these blobs, we need a new kind of ‘net’, distinguishing between blobby things and solid ones. For instance, a funnel, with a very tight hole. All the solid cubical things will get stuck before reaching the hole, whereas slimy things will go through it easily, by changing their form.
Again, chemistry can be thought of as the rope net, screening everything passing through it, without exceptions. As the net wants to make sure that everything has the form of its holes, so does chemistry expect that the universe is made just of chemical stuff. But then the question changes and it becomes of different nature, because we want to capture specific aspects of the universe that the first screening was incapable of grasping, due to its constitution. We need new instruments and laws: in one case a funnel, to distinguish blobs from solids, in the other case natural selection, to appreciate biological evolution.
No one denies that a technologically advanced scanner could both detect the cubical structure of the falling objects, and also distinguish blobs from solids, but a scanner is not a sophisticated version of a rope net: It is a new kind of net!
It is important not to be fooled by this second analogy into thinking that there is something special in the blobs. The first screening couldn’t simply distinguish them from solids, but it accounted perfectly for both insofar as it was concerned with the task of letting specific objects fall through its holes. It is not the constitution of blobs that is special, it is the constitution of the net that is concerned only with a limited task. The same can be said with respect to chemistry: it is not that biological objects have a special constitution, it is rather that the constitution of the chemical science is such that it oversees them. It can only see a bunch of molecules, and this independently of how sophisticated its calculations are.
Indeed, I am not an emergentist (click here for my criticism of emergentism). I do not believe that specific conformations of molecules give rise to new (ontological) properties. There is nothing new in the universe when a lioness chases an antelope: no new special property is added to molecules and void. All I am claiming is that we are not asking that question when we are looking for the evolutionary significance of what is happening: we are looking for the laws of living organisms, not those of molecules. There is no new stuff, only new laws.
M asked for more concrete examples, but I don’t really know what I shall be adding to these arguments. We started from the “concrete question” and then went backwards to explore the more abstract prerequisites. At the same time, I am not sure if I made justice to his point, also because at the end of the talk he mentioned an example of how computers work, namely with binary codes, which make appear “windows” on our screens and the words I am typing right now. Even if we had no time to develop that point further, my intuition is that it wouldn’t have been much different from the ones already treated: the words you are reading belong to a realm of meaning that is obscure at the binary level of 0s and 1s, despite the fact that, for each character/word/phrase, there is a corresponding formula in binary language, without remainders.
The reason for my intuition about how to interpret M’s view is also based on something he said after the conference (I promised at the beginning of this letter that I would have connected the two topics, and here I am). He said that we (human beings) are not rational, after all. That was puzzling and sounded very wrong at first. How couldn’t we be rational? We had a meeting and we both showed up, we were hungry and we went eating, we had reasons for our beliefs and we discussed. How are these things not rational?
The reason why M said that we are “not-rational-after-all”, is probably to show skepticism about the idea that there is anything over and above “neuronal determination”. After the disquisitions in this letter, I hope it is clear that the two fields (rationality and neurology) can belong to different sciences, one more fundamental than the other, but independent from one another. When someone is asking “Why are you eating pizza?” and you answer “Because I have a neurological asset that determines my eating a pizza” you clearly misunderstood the question, for neurological determination is indeed what is going on, but not what was asked. The question was about your reasons for eating a pizza (being hungry for instance, or spending some time with a friend in a restaurant), not about some state of affairs in the world. If the question were understood descriptively rather than normatively, you couldn’t protest by saying “you should have waited for me to join” or complained about the fact that Italians decided to eat pizza in Germany. For neurological descriptions don’t allow for assessment of decisions: the very concept of decision would be meaningless. And, by the way, we ate that pizza because it was delicious.