Biology vs Physics: Two Ways of Doing Science?

Do physics and biology work in fundamentally different ways? Why?

I am an evolutionary biologist by training, before I turned to philosophy of science. And I have always been fascinated by the fact that biology seems to be on one side of what I call the “teleonomic divide” in science. Teleonomy is the appearance of purposefulness that results from some type of natural process, chiefly (exclusively, really) natural selection. The term comes from the Greek words, telos (end, goal) and nomos (law), and is crucially distinguished from teleology, where the purposefulness is not just apparent, but actual: it is either the result of a supernatural cause (“god”) or, more obviously, of human activity. The pertinent Greek words here, tellingly, are again telos (end, goal) and logos (reason, explanation).

Deploying the distinction between teleonomy and teleology, then, we could roughly divide the sciences in the following way: at one end of the spectrum, physics, chemistry, astronomy and geology are neither teleonomic nor teleologic. It makes no sense to ask what is the purpose or goal of an electron, a molecule, a planet or a mountain. At the opposite end we find clearly teleologic sciences, like psychology, sociology and economics. In these cases it is actually mandatory to ask what is the purpose behind a certain (human) behavior, social structure or economic feature, without which one would not understand what is going on.

Then there is biology, poised at the brink of these two groups. Ever since Darwin, we have ceased to think of biological systems in terms of intelligent design (pace the creationist), so teleology is out of the question. And yet, teleonomic talk not only comes natural to biologists, but seems to be indispensable to their trade: it makes perfect sense to ask what is the eye for, or what is the purpose of lungs, or what is the goal that justifies the peacock’s tail or the bowerbird’s nest.

The question is: why? What is it about the objects of study of biology that makes teleonomic talk appropriate, indeed, pretty necessary? That is the topic of a nice paper by Marco Buzzoni, recently published in the Journal of General Philosophy of Science under the title “Causality, Teleology, and Thought Experiments in Biology.” [Notice that throughout his paper Buzzoni talks of teleology, not teleonomy, I will return to this crucial point at the end.]

Buzzoni begins by quoting the venerable evolutionary biologist Ernst Mayr, one of the architects of the so-called “Modern Synthesis,” biology’s equivalent of the Standard Model in physics: “[the battle over the status of biology] has been waged between two distinct camps. One claims that biology does not differ in principles and methods from the physical sciences, and that further research, particularly in molecular biology, will in time lead to a reduction of all of biology to physics. [...] The other camp claims that biology fully merits status as an autonomous science because it differs fundamentally in its subject matter, conceptual framework, and methodology from the physical sciences.”

There is no question in Mayr’s, Buzzoni’s and my own mind that the first option is simply not viable. Yes, of course biological organisms are made of molecules, which are made of atoms, which are made of subatomic particles, the behavior of which can be explained in physical terms. But it is equally obvious to any biologist that if you simply describe the physical-chemical behavior of living organisms and their parts without also asking why they are the way they are, you are missing the entire point of doing biology.

Philosopher Michael Polanyi, quoted by Buzzoni, said something similar of man-made machines: “[they] can be recognized as such only by first guessing, at least approximately, what they are for and how they work. Their operational principles can then be specified further by technological investigations. Physics and chemistry can establish the conditions for their successful operation and account for possible failures, but a complete specification of a machine in physical-chemical terms would dissolve altogether our knowledge of the machine.”

The problem is that living organisms are not machines (again, pace the favorite analogy deployed by creationists). Machines are intelligently designed objects, living organisms are the result of natural (meaning non-human) processes. Unless one embraces some variety of vitalism (the idea that biological organisms are somehow qualitatively distinct from inert matter) — which Mayr, Buzzoni and myself don’t do — then one has some interesting philosophical explaining to do.

The way Buzzoni goes at it is by recasting biological hypotheses as thought experiments. In general, he follows Kant when he said that an experiment can be treated as a “question put to nature.” Obviously, experiments are teleological actions, they have a purpose (that of the scientist). And the fact that we can do experiments in physics and chemistry clearly shows that “teleology and efficient-mechanical causality are not only compatible but that final causes are actually the condition of the epistemic possibility of mechanical ones, since without our knowledge of final causes there would be no experiment and therefore no imputation of mechanical causes.”

The idea, then, is that in biology research is based on the deployment of “what for?” thought experiments that use teleology as a heuristic to “investigate living beings in the intersubjectively testable and reproducible way typical of Galilean science.”

In essence, this means that — as a matter of practical strategy — biologists have been successful in what they do by interrogating nature, so to speak, from a fictional teleological perspective, as if living organisms had purposes and goals analogous to those of humans. Buzzoni is very explicit that he is not making any ontological claim about teleology, i.e., he is not speculating on why this strategy works so well in biology but makes no sense in physics. It just does, and scientists, being pragmatic by nature, use it because it works, not because they buy into any particular underlying ontological position.

The problem, as Buzzoni himself recognizes toward the end of his paper, is that we are still left with the unanswered question: why is it, exactly, that a teleological heuristic works so well for certain kinds of objects of study, but is entirely irrelevant for others? He says: “One might still ask the further question whether this depends upon an ontological difference [between the objects of study of physics and biology]. Philosophically speaking, I do not think that any sufficient reason has yet been given for answering this question affirmatively, even though there are some moral reasons for doing so. But this is not the interesting point.”

Well, here I beg to differ. That is an interesting point, and very much so. One way to go about it, perhaps, is to deny that there is any purpose at all in the universe, even human. It has become rather fashionable these days to think of human beings as biological robots with the illusion of things like free will, consciousness, purpose, and so on. For a number of reasons I will not go into here (but I did here!), I think this is not very promising, scientifically or philosophically.

Then again, as I stated above, I don’t think that there are two types of matter in the cosmos, non-living and living. Or worse, three: non-living, living and conscious. And I also don’t think that everything in the universe is alive, or conscious (the latter notion, panpsychism, has itself been enjoying an unwelcome revival of late in philosophy).

The answer, seems to me, the one given by Darwin, providing the foundation of the distinction with which we started this essay, and which Buzzoni does not deploy, the one between teleonomy and teleology. Living organisms can proficiently be thought of in teleonomic terms because they are the result of a process — evolution by natural selection — that truly does mimic goals and purposes. Mountains, planets, galaxies and all the rest, in contrast, are the products of different, more elemental, processes, which do not generate teleonomic systems.

What, finally, is at the root of the difference between teleonomy and teleology, i.e. between the appearance of purposes and actual purposes, as in human activities? The coming into existence of consciousness, which as of now we simply do not understand well enough to account for in satisfactory scientific terms (though we are making progress). In other words, cognitive science is still waiting for its Darwin. Hopefully some time soon.