Progress in Science — III

[for a brief explanation of this ongoing series, as well as a full table of contents, go here]

Progress in science: different philosophical accounts

The above discussion has largely been framed in terms that do not explicitly challenge the way most scientists think of their own enterprise: as a teleonomic one, whose ultimate goal is to arrive at (or approximate as far as possible) an ultimate, all-encompassing theory of how nature works, Steven Weinberg’s (1994) famous “theory of everything.” However, the epistemic, semantic and functionalist accounts do not all seat equally comfortably with that way of thinking. Bird’s epistemic approach can perhaps be most easily squared with the idea of teleonomic progress, since it argues that science is essentially about accumulation of knowledge about the world. The obvious problem with this, however, is that accumulation of truths is certainly necessary but also clearly insufficient to provide a robust sense of progress, since there are countless trivial ways of accumulating factual truths that no one in his right mind would count as scientific advances (e.g., I could spend a significant amount of grant funds to count exactly how many cells there are in my body, then in the body’s of the next person, and so on. This would hardly lead to any breakthrough in human cell biology, though.)

Niiniluoto’s semantic approach, based as it is on the idea of verisimilitude, is a little less friendly to the idea of a single ultimate goal for science. We have seen above that Niiniluoto’s way of cashing out “verisimilitude” is locally defined, and provides no way to compare how close we are to the truth on one specific problem, or even in a relatively broad domain, of science to another such problem or domain. So, for instance, progress toward truth about, say, ascertaining the neuronal underpinnings of human consciousness has prima facie nothing at all to do with progress in understanding how general relativity and quantum mechanics can be reconciled with each other in cases in which they give divergent answers.

Finally, the functionalist approach that can be traced to Kuhn and has been brought forth by Laudan, among several others, is even less friendly to a broad scale teleonomic view of science. Just recall Kuhn’s own skepticism about the possibility of a “coherent direction of ontological development” of scientific theories and his qualified distancing himself from a “relativist” view of scientific knowledge. If science is primarily about problem-solving, as both Kuhn and Laudan maintain, then there is only a limited sense in which the enterprise makes progress, Kuhn’s “evolutionary” metaphor notwithstanding.

But things can get even more messy for defenders of a straightforward concept of scientific progress — as, again, I take most scientists to be. As a scientist myself, I have always assumed that there is one thing, one type of activity, we call science. More importantly, though I am a biologist, I automatically accepted the physicists’ idea that — in principle at the least — everything boils down to physics, that it makes perfect sense to go after the above mentioned “theory of everything.” Then I read John Dupré’s The Disorder of Things (Dupré 1993), and that got me to pause and think hard.

I found Dupré’s book compelling not just because of his refreshing, and admittedly consciously iconoclastic tone, but also because a great deal of it is devoted to subject matters, like population genetics, that I actually know a lot about, and am therefore in a good position to judge whether the philosopher got it right (mostly, he did). Dupré’s strategy is to attack the idea of reductionism by showing how it doesn’t work in biology. He rejects the notion of a unified scientific method (a position that is nowadays pretty standard among philosophers of science), and goes on to advocate a pluralistic view of the sciences, which he claims reflects both what the sciences themselves are finding about the world (with a multiplication of increasingly disconnected disciplines and the production of new explanatory principles that are stubbornly irreducible to each other), as well as a more sensible metaphysics (there aren’t any “joints” at which the sciences “cut nature” — Kitcher’s “natural kinds” from above — so that there are a number of perfectly equivalent ways of thinking about the universe and its furnishings).

Dupré’s ideas have a long pedigree in philosophy of science, and arguably arch back to a classic and highly influential paper by Jerry Fodor (1974), “Special sciences (or: the disunity of science as a working hypothesis),” and are connected to Nancy Cartwright’s (1983) How the Laws of Physics Lie and Ian Hacking’s (1983) already mentioned Representing and Intervening.

Let me start with Fodor, whose target was, essentially, the logical positivist idea that the natural sciences form a hierarchy of fields and theories that are (potentially) reducible to each next level, forming a chain of reduction that ends up with fundamental physics at the bottom. So, for instance, sociology should be reducible to psychology, which in turn collapses into biology, the latter into chemistry, and then we are almost there. But what does “reducing” mean, in this context? At the least two things: call them ontological and theoretical. Ontologically speaking, most people would agree that all things in the universe are indeed made of the same substance, be it quarks, strings, branes or whatever; moreover, complex things are made of simpler things. For instance, populations of organisms are collections of individuals, while atoms are groups of particles, etc. Fodor does not object to this sort of reductionism.

Theoretical reduction, however, is a different beast altogether, because scientific theories are not “out there in the world,” so to speak, they are creations of the human mind. This means that theoretical reduction, contra popular assumption among a number of scientists (especially physicists), does most definitely not logically follow from ontological reduction. Theoretical reduction was the holy (never achieved) grail of logical positivism: it is the ability to reduce all scientific laws to lower level ones, eventually reaching our by now infamous “theory of everything,” formulated of course in the language of physics. Fodor thinks that this will not do. Consider a superficially easy case. Typically, when one questions theory reduction in science one is faced with both incredulous stares and a quick counter-example: just look at chemistry. It has successfully been reduced to physics, so much so that these days there basically is no meaningful distinction between chemistry and physics. But it turns out after closer scrutiny that there are two problems with this move: first, the example itself is questionable; second, even if true, it is arguably more an exception than the rule.

As Weisberg et al. (2011) write: “Many philosophers assume that chemistry has already been reduced to physics. In the past, this assumption was so pervasive that it was common to read about ‘physico/chemical’ laws and explanations, as if the reduction of chemistry to physics was complete. Although most philosophers of chemistry would accept that there is no conflict between the sciences of chemistry and physics, most philosophers of chemistry think that a stronger conception of unity is mistaken. Most believe that chemistry has not been reduced to physics nor is it likely to be.” For instance, both Bogaard (1978) and Scerri (1991, 1994) have raised doubts about the feasibility of reducing chemical accounts of molecules and atoms to quantum mechanics. Weisberg et al. (2011) add examples of difficult reductions of macroscopic to microscopic theories within chemistry itself (let alone between chemistry and physics), even in what are at first glance obviously easy cases, like the concept of temperature. I will refer the reader to the literature cited by Weisberg et al. for the fascinating arguments that give force to this sort of cases, but for my purposes here it suffices to note that the alleged reduction has been questioned by “most” philosophers of chemistry, which ought to cast at least some doubt on even this oft-trumpeted example of theoretical reduction. Another instance, closer to my own academic home field, is Mendelian genetics, which has also not been reduced to molecular genetics, contra to what commonly assumed by a number of geneticists and molecular biologists (Waters 2007). In this case one of the problems is that there are a number of non-isomorphic concepts of “gene” being used in biology, which gets in the way of achieving full inter-theoretical reduction.

Once we begin to think along these lines, the problems for the unity of science thesis — and hence for straightforward accounts of what it means to have scientific progress — are even worse. Here is how Fodor puts it, right at the beginning of his ’74 paper: “A typical thesis of positivistic philosophy of science is that all true theories in the special sciences [i.e., everything but fundamental physics, including non-fundamental physics] should reduce to physical theories in the long run. This is intended to be an empirical thesis, and part of the evidence which supports it is provided by such scientific successes as the molecular theory of heat and the physical explanation of the chemical bond. But the philosophical popularity of the reductivist program cannot be explained by reference to these achievements alone. The development of science has witnessed the proliferation of specialized disciplines at least as often as it has witnessed their reduction to physics, so the wide spread enthusiasm for reduction can hardly be a mere induction over its past successes.” In other words, echoing both Fodor and Dupré one could argue that the history of science has produced many more divergences at the theoretical level — via the proliferation of new theories within individual “special” sciences — than it has produced successful cases of reduction. If anything, historical induction points the other way around from the commonly accepted story.

Turns out that even some scientists seem inclined toward at least some bit of skepticism concerning the notion that “fundamental” physics is so, well, (theoretically) fundamental. (It is, again, in the ontological sense discussed above: everything is made of quarks, or strings, or branes, or whatever.) During the 1990’s the American scientific community witnessed a very public debate concerning the construction of a Superconducting Super Collider (SSC), which was the proposed antecedent of the Large Hadron Collider that recently led to the discovery of the Higgs boson. The project was eventually nixed by the US Congress because it was too expensive. Steven Weinberg testified in front of Congress on behalf of the project, but what is less known is that some physicists testified against the SSC, and that their argument was based on the increasing irrelevance of fundamental physics to the rest of physics — let alone to biology or the social sciences. Here is how solid state physicist Philip W. Anderson (1972) put it early on, foreshadowing the arguments he later used against Weinberg at the time of the SSC hearings: “The more the elementary particle physicists tell us about the nature of the fundamental laws, the less relevance they seem to have to the very real problems of the rest of science.” So much for a fundamental theory of everything.

Let us go back to Fodor and why he is skeptical of theory reduction, again from his ’74 paper: “If it turns out that the functional decomposition of the nervous system corresponds to its neurological (anatomical, biochemical, physical) decomposition, then there are only epistemological reasons for studying the former instead of the latter [meaning that psychology couldn’t be done by way of physics only for practical reasons, it would be too unwieldy]. But suppose there is no such correspondence? Suppose the functional organization of the nervous system cross cuts its neurological organization (so that quite different neurological structures can subserve identical psychological functions across times or across organisms). Then the existence of psychology depends not on the fact that neurons are so sadly small, but rather on the fact that neurology does not posit the natural kinds that psychology requires.” And just before this passage in the same paper, Fodor argues a related, even more interesting point: “If only physical particles weren’t so small (if only brains were on the outside, where one can get a look at them), then we would do physics instead of paleontology (neurology instead of psychology; psychology instead of economics; and so on down). [But] even if brains were out where they can be looked at, as things now stand, we wouldn’t know what to look for: we lack the appropriate theoretical apparatus for the psychological taxonomy of neurological events.”

The idea, I take it, is that when physicists say that “in principle” all knowledge of the world is reducible to physics, one is perfectly within one’s rights to ask what principle, exactly, are they referring to. Fodor contends that if one were to call up the epistemic bluff the physicists would have no idea of where to even begin to provide a reduction of sociology, economics, psychology, biology, etc. to fundamental physics. There is, it seems, no known “principle” that would guide anyone in pursuing such a quest — a far more fundamental issue than the one imposed by merely practical limits of time and calculation. To provide an analogy, if I told you that I could, given the proper amount of time and energy, list all the digits of the largest known prime number, but then decline to actually do so because, you know, the darn thing’s got 12,978,189 digits, you couldn’t have any principled objection to my statement. But if instead I told you that I can prove to you that there is an infinity of prime numbers, you would be perfectly within your rights to ask me at the least the outline of such proof (which exists, by the way), and you should certainly not be content with any vague gesturing on my part to the effect that I don’t see any reason “in principle” why there should be a limit to the set of prime numbers.

Tantalizing as the above is for a philosopher of science like myself, in order to bring us back to our discussion of progress in science we need some positive reasons to take seriously the notion of the impossibility of ultimate theory reduction, and therefore to contemplate the idea of a fundamental disunity of science and what it may mean for the idea of progress within the scientific enterprise. Cartwright (1983) and Hacking (1983) do put forth some such reasons, even though of course there have been plenty of critics of their positions. Cartwright has articulated a view known as theory anti-realism, which implies a denial of the standard idea — almost universal among scientists, and somewhat popular among philosophers — that laws of nature are (approximately) true generalized descriptions of the behavior of things, especially particles (or fields, doesn’t matter). Rather, Cartwright suggests that theories are statements about how things (or particles, or fields) would behave according to idealized models of reality.

The implication here is that our models of reality are not true, and therefore that — strictly speaking — laws of nature are false. The idea of laws of nature (especially with their initially literal implication of the existence of a law giver) has been controversial since it was championed by Descartes and opposed by Hobbes and Galileo [5], but Cartwright’s suggestion is rather radical. She distinguishes between two ways of thinking about laws: “fundamental” laws are those postulated by the realists, and they are meant to describe the true, deep structure of the universe. “Phenomenological” laws, by contrast, are useful for making empirical predictions, they work well enough for that purpose, but strictly speaking they are false.

Now, there are a number of instances in which even physicists would agree with Cartwright. Take the laws of Newtonian mechanics: they do work well enough for empirical predictions (within a certain domain of application), but we know that they are false if they are understood as being truly universal (precisely because they have a limited domain of application). According to Cartwright, however, all laws and scientific generalizations, in physics as well as in the “special” sciences are just like that, phenomenological. [6] And there are plenty of other examples: nobody, at the moment, seems to have any clue about how to even begin to reduce the theory of natural selection, or economic theories, for instance, to anything below the levels of biology and economics respectively, let alone fundamental physics. If Cartwright is correct (and Hacking argues along similar lines), then science is fundamentally disunified, and its very goal should shift from seeking a theory of everything to putting together the best patchwork of local, phenomenological theories and laws, each one of which, of course, would be characterized by its proper domain of application.

Here is how Cartwright herself puts it, concerning physics in particular: “Neither quantum nor classical theories are sufficient on their own for providing accurate descriptions of the phenomena in their domain. Some situations require quantum descriptions, some classical and some a mix of both.” And the same goes, a fortiori, for the full ensemble of scientific theories, including all those coming out of the special sciences. So, are Dupré, Fodor, Hacking and Cartwright, among others, right? I don’t know, but it behooves anyone who is seriously interested in the nature of science to take their ideas seriously. If one does that, then it becomes far less clear that “science” makes progress, although one can still articulate a very clear sense in which individual sciences do.

The goal of this chapter was to show that the concept of progress in science — which most scientists and the lay public seem to think is uncontroversial and self-evident — is anything but. This does not mean at all that we do not have good reasons to think that science does, in fact, make progress. But when scientists in particular loudly complain that philosophy doesn’t progress they should be reminded that it is surprisingly difficult to articulate a coherent and convincing theory of progress in any discipline, including their own — where by their account it ought to be a no brainer. In the next chapter we will pursue our understanding of progress in different fields of inquiry by turning to mathematics and logic, were I think the concept definitely applies, but in a fashion that is interestingly distinct from the sense(s) in which it does in science. And it will be from a better understanding of progress in both science(s) and mathematics-logic that we will eventually be in a position to articulate how philosophy (or at least certain fields within philosophy) are also progressive.

Notes

[5] See my lay summary of this in: Are there natural laws?, by M. Pigliucci, Rationally Speaking, 3 October 2013 (accessed on 6 August 2015).

[6] Interestingly, some physicists (Smolin 2007) seem to provide support for Cartwright’s contention, to a point. In his The Trouble with Physics Smolin speculates that there are empirically intriguing reasons to suspect that Special Relativity “breaks down” at very high energies, which means that it would not be a law of nature in the “fundamental” sense, only in the “phenomenological” one. He also suggests that General Relativity may break down at very large cosmological scales.

References

Anderson, P.W. (1972) More is different. Science, 177:393-396.

Bogaard, P.A. (1978) The limitations of physics as a chemical reducing agent. Proceedings of the Philosophy of Science Association 2:345–356.

Cartwright, N. (1983) How the Laws of Physics Lie. Oxford University Press.

Dupré, J. (1993) The Disorder of Things: Metaphysical Foundations of the Disunity of Science. Harvard University Press.

Fodor, J. (1974) Special sciences (Or: the disunity of science as a working hypothesis). Synthese 28:97-115.

Hacking, I. (1983) Representing and Intervening: Introductory Topics in the Philosophy of Natural Science. Cambridge University Press.

Scerri, E. (1991) The electronic configuration model, quantum mechanics and reduction. British Journal for the Philosophy of Science 42:309–325.

Scerri. E. (1994) Has chemistry been at least approximately reduced to quantum mechanics? In: D. Hull, M. Forbes and R. Burian (eds.), PSA 1994 (Vol. 1), Philosophy of Science Association.

Smolin, L. (2007) The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next. Mariner Books.

Waters, K. (2007) Molecular genetics. Stanford Encyclopedia of Philosophy (accessed on 6 August 2015).

Weinberg, S. (1994) Against philosophy. In: Dreams of a Final Theory: The Scientist’s Search for the Ultimate Laws of Nature. Vintage.

Weisberg, M., Needham, P., and Hendry, R. (2011) Philosophy of chemistry. Stanford Encyclopedia of Philosophy (accessed on 6 August 2015).