Dirac, Bernstein, Weinberg and the limits of reductionism

Jeremy Bernstein is a physicist and science writer who has worked with some of the leading physicists of the twentieth century and has penned highly engaging volumes about science, scientists and society which I have enjoyed reading. I was thus disappointed to read his review of a new book on quantum theory by Jim Baggott in the Wall Street Journal which opens thus:

In 1929, theoretical physicist Paul Dirac announced: “The general theory of quantum mechanics is now complete. . . . The underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus completely known.” The discipline at the point was four years old. Dirac himself was just 27. But eight decades later, we see that his optimistic evaluation was too modest. In addition to a “large part of physics and the whole of chemistry,” the theory now is extended to a significant part of biology, essentially all of electronics and nuclear physics, and a large part of astrophysics and cosmology.

Really? A significant part of biology and the whole of chemistry? Both chemists and ecologists may be interested to know this. Let’s take stock of this viewpoint since it highlights a quote by Dirac which has been marshaled all too often in support of reductionism. It’s time to put the quote in context. Paul Dirac was one of the greatest scientists of the twentieth century and perhaps of all time, but he was no chemist or biologist. He made that statement about quantum mechanics in 1929 when quantum mechanics was at the height of its powers. The complete theory had just been developed by Heisenberg, Born, Schrodinger, Dirac and others and it had turned into physics’s crowning achievement. At the same time scientists like Pauling and Slater were applying the theory to chemistry. Suddenly the world seemed to be at physicists’ feet and there seemed to be no limit to what physics could achieve.

But this was not the case. The optimism about reductionism endured for the next couple of decades when physicists made monumental contributions to chemistry and molecular biology. And yet the waning years of the millennium indicated that the reach of reductionism was distinctly limited. We were just getting warmed up. As we made forays into expansive fields of chemistry and biology like self-assembly, chemical biology, population genetics, ecology, systems biology and neuroscience, it became clear that the essence of complex systems was emergence. Emergent properties seemed to demand understanding at their own levels and could not be reduced to interactions between particles and fields. At the level of every science there emerged foundational laws, not reducible to deeper principles, that served as the bedrock for that particular science. Today, as we encounter new horizons in the study of signaling networks, brain plasticity and chaotic ecological systems, it’s clear that we will have to find and formulate fundamental laws specific to every system and science. No, if anything, Dirac’s statement was not too modest but too ambitious; as spectacular as its predictions have been, “a significant part of biology” and chemistry cannot be explained on the basis of quantum theory.

In fact, although I am not an expert in cosmology, the extension of quantum predictions even to cosmology seems surprising to me. Isn’t gravity the other dominant force that needs to be taken into account when formulating cosmological explanations? And isn’t the welding of quantum theory and gravity the great unsolved problem of physics? To me the inclusion of large parts of cosmology and astrophysics under the quantum fold seems premature.

Interestingly, this abiding interest in reductionist statements reminds me a of minor debate about reductionism between Freeman Dyson and Steven Weinberg that took place in the 90s. Dyson who has been critical of reductionism for a while penned an expressive piece arguing against reductionist philosophy in the New York Review of Books. In reply, Weinberg who has been an arch reductionist replied with his own spirited rebuttal. This rebuttal has been discussed in Weinberg’s engaging collection of essays “Facing Up: Science and its Cultural Adversaries”.

Weinberg defined what he thought were two distinct critiques of reductionism. One was the critique of reductionism as a working principle. The other was a more fundamental, philosophical critique of reductionism as being unable to account for higher-order phenomena even in principle. Weinberg thus was making a distinction between reductionism in practice and reductionism in principle. According to him, scientists like Dyson who criticized reductionism really had a problem with the former manifestation of reductionism, as a working principle that did not really allow them to solve problems in chemistry, biology, economics or psychology. In contrast, reductionism in principle was alive and well and was being the unwitting victim of the anti-reductionists’ axe. In essence Weinberg was saying that, sure, even if quarks cannot directly help you to solve the mysteries of chromosomes, they still surely account for chromosomal properties in principle.

But to me such a distinction is meaningless beyond a point. The working scientist in his or her everyday scientific life really only cares about reductionism as a working principle, not as final causation. The fact that quarks can account for chromosomes in principle is not very consequential; a biologist could care less if there were goblins manipulating the fundamental constituents of biological systems. In addition, a lot of biology and chemistry progresses through the construction of models which are not even required to reflect the presence of the very fundamental laws. At the very least, the extolling of reductionism as being able to ultimately account for all kinds of phenomena is a trivial statement; it’s like saying that everything is made out of atoms. So what? That hardly helps us cure cancer.

Ultimately, I suspect the argument may be more about semantics, about the meanings of the words “explain” and “account for”. But the last word actually belongs to Paul Dirac. In his quote, Bernstein left out something crucial that Dirac said. Yes, Dirac did seem to claim that quantum mechanics could explain “the whole of chemistry”, but he also said later that

“…The difficulty is only that the exact application of these laws leads to equations much too complicated to be soluble. It therefore becomes desirable that approximate practical methods of applying quantum mechanics should be developed, which can lead to an explanation of the main features of complex atomic systems without too much computation.”

It’s those words “approximation”, “complex” and “computation” that encompass the essence of chemistry, biology and all the other sciences which Dirac did not mention.

He may have been right after all.

Models, laws and the limits of reductionism

I am currently reading Stuart Kauffman’s “Reinventing the Sacred” and it’s turning out to be one of the most thought-provoking books I have read in a long time, full of mind-bending ideas. Kauffman who was originally trained as a doctor was for many years a member of the famous Institute for Complexity in Santa Fe, which is a bastion of interdisciplinary research.

Kauffman is a kind of polymath who draws upon physics, chemistry, biology, computer science and economics to essentially argue the limitations of reductionism and the existence of emergent phenomena. He makes some fascinating arguments for instance about biology not being reducible to specific physics. One of the main reasons this cannot be done is because the evolution of complex biological systems is contingent and can follow any number of virtually infinite courses depending on slightly different conditions; according to Kauffman, this infinity is not just a ‘countable infinity’ but an ‘uncountable one’ (more on this mind-boggling distinction later). Biological systems are also highly non-linear and full of feedback and ‘surprises’ and these qualities make their prediction not just very difficult in practice but even in principle.

I am sure I will have much more to say about Kauffman’s book later, but for now I want to focus on his argument against reductionism based on what is called the ‘multiple platform’ framework. Kauffman’s basic thesis draws on an argument made by the Nobel laureate Philip Anderson. Anderson wrote a groundbreaking article in Science in 1972 extolling the limits of reductionism. To illustrate the multiple platform principle, he talked about computers processing 1s and 0s and manipulating them to give a myriad number of results. The question is: is the processing of 1s and 0s in a computer uniquely dependent upon the specific physics involved (which in this case would be quantum mechanics)? The answer may seem obvious but Anderson says that it’s hard to make this argument, since one can also get the same results from manipulating buckets that are either empty (0s) or filled with water (1s). Thus, the binary operations of a computer cannot be reduced to specific physics since they can be modeled by ‘multiple platforms’.

Another example that Kauffman cites is of the Navier-Stokes equations, the basic equations of fluid dynamics. The equations are classical and are derived from Newton’s laws. One would think that they would be ultimately reducible to the movements of individual particles of fluid and thus to quantum mechanics. Yet as of today, nobody has found a way to derive the Navier-Stokes equations from those of quantum mechanics. However, the physicist Leo Kadanoff has actually ‘derived’ these equations by using a rather simple ‘toy world’ of beads on a lattice. The movement of fluids and therefore the equations can be modeled by moving the beads around. Thus, we again have an example of multiple platforms leading to the same phenomenon, precluding the unique dependence of the phenomenon on a particular set of laws.

All this is extremely interesting, but I am not sure I follow Kauffman here. The toy world or the bucket brigades that Kadanoff and Anderson talk about are models. Models are very different from physical laws. Sure, there can be multiple models (or platforms) for deriving a given set of phenomena, but the existence of multiple models does not preclude dependence on a unique set of laws. A close analogy which I often think of is from molecular mechanics. A molecular mechanics model of a molecule assumes the molecule to be a classical set of balls and springs, with the electrons neglected. It is supposed to reproduce the properties of molecules like their geometry and energy. By any definition this is a ludicrously simple model that completely ignores quantum effects (or at least takes them into consideration implicitly by getting parameters from experiment). Yet, with the right parametrization, it works well-enough to be useful. There could conceivably be many other models which could give the same results. Yet nobody would make the argument that the behavior of molecules modeled in molecular mechanics is not reducible to quantum mechanics.

Kauffman’s argument that the explanatory arrows don’t always point downwards because one cannot always extrapolate upwards from lower-level phenomena is very well-taken. Emergent properties are surely real. But at least in the specific cases he considers, I am not sure that one can make an argument about phenomena not being reducible to specific physics simply because they can be derived from multiple platforms. The multiple platforms are models. The specific physics constitutes a set of laws, which is quite different.

PLEASE, SAVE SCIENCE FROM THE “HOLISTS”

There are two kinds of environmentalists. One kind which is a scarce breed consists of the ones who are willing to do cost-benefit analysis and apply rational scientific thinking based on available facts to suggest policy. The other kind, sadly even now the majority, are against nuclear power, are not averse to hijacking oil tankers to make their point, and are more concerned about the fate of koala bears than about prudent science-based solutions to climate change. These environmentalists often, but not always, include far-left anti-corporate activists. Many of them tout “holistic farming” and vague notions of glorified “scientific solutions” to the world’s food, medical and environmental problems. Most jarringly, they hold many scientists in contempt and subscribe to the strange postmodernist view of science, wherein science is “just another way of looking at reality”.

Vandana Shiva, who has a PhD. in physics from the University of Western Ontario, is unfortunately one of them.

Sovietologist brings one of her crazier articles to my attention. According to Shiva, the traditional reductionist approach to science is not only incorrect but responsible for the deaths of thousands of people. Shiva thinks that the reductionist approach has harmed science and essentially should be side-lined and abandoned in favour of a more generalized “holistic” approach. Thrown out of the window are the benefits to billions that reductionist science has brought.

According to Shiva,

“In order to prove itself superior to alternative modes of knowledge and be the only legitimate mode of knowing, reductionist science resorts to suppression and falsification of facts and thus commits violence against science itself, which ought to be a search for truth. We discuss below how fraudulent this claim to truth is.”

Shiva then helpfully rails against every application of science from medicine to agriculture to energy. I don’t think it’s even worth discussing the many glaring flaws and rampant cherry picking in her ramblings, but her opinions of medicine especially rankled me

Simple ailments have been cured over centuries by appropriate use of concoctions made from plants and minerals found in nature. ‘Scientific medicine’ removes the diversity by isolating ‘active’ ingredients or by synthesizing chemical combinations. Such processing first involves violence against the complex balance inherent in natural resources. And then, when the chemical is introduced into the human body, it is often a violation of human physiology.

Little does Shiva realize that by obfuscating the issue and presenting medical therapy as a “violation of human physiology” she is obscuring the fact that that’s what precisely any foreign substance introduced in the body does. And by the way, perhaps Shiva has forgotten the billions of lives that “active ingredients” have saved all over the world. She gives the example of the psychoactive drug reserpine isolated from the beautiful flowering plant Rauwolfia serpentina. It was perhaps the first drug that brought dignity and benefits to countless patients of psychoses. Then, it began showing unacceptable side effects. But Shiva not only does not stress the benefits, but stops here. There is no discussion of scores of future anti-psychotic drugs which were focused on reducing these side-effects and improving efficacy. Even today we don’t have the perfect drug for schizophrenia, but intense efforts continue in both academia and industry. For Shiva these efforts are trivial and even misguided.

Not surprisingly then, Shiva launches into an litany of benefits for “natural” concoctions. As with other extreme propaganda, there is a shred of truth to this contention. There is no doubt that many Ayurvedic medicines bring real benefits. However, there is merit to isolating the active ingredient from any such natural source and modifying it to reduce toxicity. That is how most drugs have been developed, by starting from an isolated natural molecule and then tuning its properties to reduce toxicity and improve potency. Shiva needs to educate herself a little about the process of drug discovery.

However, Shiva’s real agenda, hidden all along, becomes clear at the end. If postmodernist leanings don’t move you, compassionate socialist ones surely will:

But it is highly unlikely that medical science and pharamaceutical establishments will pay heed. For the reductionist medical science cannot but manufacture reductionist products and undermine the balance inherent in natural products. The multinationals that produce synthetic drugs in pursuit of fabulous profits and ignore their toxic side effects do not care. When they are forbidden to sell some harmful drugs in the home countries, they find a lucrative market in the third world, where the élites, including the medical establishment, are usually bewitched by anything that is offered as scientific, especially if it comes wrapped in pretty pay-offs. They give a free hand to multinationals to buy medicinal plants at dirt-cheap rates and sell the processed pills in the third-world countries at exorbitant prices and at enormous cost to the health of the people. The élites cannot accept that it would be more equitable socially, cheaper economically, conductive to self-reliance politically, and more beneficial medically for the third-world countries to use the plants locally according to time-tested indigenous pharmacology.

While multinational drug companies and the third-world political élites are out for profits, the third-world intellectual élites, eager to prove their scientific temper, join in a chorus to denounce indigenous therapeutics and related knowledge systems as hocus-pocus and their practice as quackery. It is through this mixture of misinformation, falsehood and bribes that a reductionist medical science has established its monopoly on medical knowledge in many societies.

That’s right. The billions of lives that have been saved by the “elitist” multinational drug corporations are nothing compared to the virulent and rampant capitalism they have have infected third world populations with. If it’s a private corporation, then by default it must be part of a global conspiracy to oppress poor people in developing countries.

As noted before, Shiva’s entire essay contains too much cherry picking, straw man arguments and misleading information to criticize here. And again, Shiva tugs at the fine line between some legitimate objections to reductionist science and a full-blown irrational attack on its methods. We don’t need Shiva to tell us that reductionist methods have their limitations; consider the recent emergence of fields like systems biology where scientists are trying to grapple to get a better perspective on overcoming these limitations. But no serious scientific critic of reductionist science will deny the immense benefits that it has served us since the dawn of humanity. Almost all the fruits of scientific research that we enjoy have come from reductionist science, and that will continue to be so. Disparaging wholesale the benefits of reductionist science and deriding the huge windfall of discoveries that reductionist science had bequeathed to us is a tremendous insult to the very edifice of scientific discovery. But then that’s the standard agenda of the postmodernist-socialists; to contend that science is “just another way” of looking at reality and to charge scientists with having a “monopoly over the truth”.

I have a simple suggestion for Shiva which I am sure she would not be loathe to accept. Next time she suffers from a deadly pathogenic infection, she should not take any antibiotic or drug manufactured by the evil companies. She should subsist on coconut water, isabgol and curd to ward off her illness. Shiva would then be truly walking the talk. Not only would she be proving her point about reductionist science doing her more harm than good and about antibiotics simply being one way among many to “look at reality”, but her admirable bed-ridden efforts would be a true slap in the face of those evil multinational drug companies.