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Science and Consensus

Two heads good, three heads better

Roger Sandall

One man’s experience is nothing if it stands alone.
C. S. Peirce

Steven Weinberg’s article discussing Einstein’s mistakes in last month’s Physics Today was characteristically measured and respectful. But to anyone interested in the zig-zag progress of science—its diligent and unceasing course corrections—a more dramatic and revealing article about Einstein had already appeared in the same journal last September.

This was Daniel Kennefick’s account of Einstein’s first experience of anonymous peer review. It was an ordeal he had never been exposed to in Europe, and when he encountered it in America the great man didn’t like it one bit.

The unprecedented situation arose in 1936 when Einstein sent a paper to The Physical Review. Kennefick explains that at that time the Review was rapidly becoming “the world’s premier journal of physics”, and editor John Tate took an austere view of his responsibilities. Nobody—not even the most distinguished contributor—could expect to be favored or indulged.

When a paper on gravitational waves arrived from Einstein, Tate invited a reviewer to comment; the reviewer’s anonymous comments were damaging; and Einstein, “in high dudgeon”, refused to publish in The Physical Review ever again.

The paper and its details are here of little concern. Einstein shared authorship with another physicist named Nathan Rosen, and together they suggested that gravitational waves, which by the 1930s most scientists thought must exist in principle, were an illusion. But Percy Robertson, the reviewer invited to comment on their paper, was not convinced.

Well, this is a job! (wrote Robertson to the editor.) If Einstein and Rosen can establish their case, this would constitute a most important criticism of the general theory of relativity. But I have gone over the whole thing with a fine-tooth comb (mainly for the good of my soul!), and can’t for the life of me see that they have established it.

After explaining why this was so, Robertson went on to recommend that his criticisms be submitted to the authors for their consideration. Alternatively, he suggested that Tate might go ahead and publish it as it stood, since the spin-off and general controversy might be beneficial anyway: “Such a paper would be certain to give rise to a lot of work in this field of gravitational waves, which might be a good thing—provided they didn’t flood you out of house and home.”

In the event the editor decided not to publish, but to send Einstein and Rosen the anonymous reviewer’s comments. Einstein angrily replied:

Dear Sir,

We (Mr Rosen and I) had sent you our manuscript for publication and had not authorized you to show it to specialists before it is printed. I see no reason to address the—in any case erroneous—comments of your anonymous expert. On the basis of this incident I prefer to publish the paper elsewhere.

This he proceeded to do in 1937 in the Journal of the Franklin Institute—but not before taking on board the reviewer’s “erroneous” corrections (having been later persuaded that they were needed), and radically altering both his argument and its conclusions.

The two heads of Einstein and Rosen may or may not have been better than one in arriving at their original defective formulation. But three heads were certainly better than two in establishing where Einstein and Rosen went wrong, and the whole episode is a good example of the process of intellectual winnowing, by other minds, through which scientific error is detected and truth established—little by little, step by step, on the path to eventual consensus.

The new cynicism

Mistakes in science bring howls of glee from its enemies—some of whom evidently see science as a mistake in itself. A school of critics dubbed The New Cynics by Susan Haack believe scientific work to be riddled with error, if not downright absurdity. Their prophet was the famous Paul Feyerabend. From his pad in Berkeley he promised to free us from “the tyranny of… such abstract concepts as ‘truth’, ‘reality’, and ‘objectivity’’ and went so far as to claim that scientists were little better than practitioners of voodoo.

Others like Bruno Latour argued that science was mainly about academic egos, rivalry, and power. Now, writes Haack, “New Cynics like Harry Collins assure us that ‘the natural world has a small or non-existent role in the construction of scientific knowledge’”, while Kenneth Gergen maintains that the validity of theoretical propositions in the sciences, “is in no way affected by factual evidence.” (In no way? There has to be something wrong there.)

In Haack’s Defending Science Within Reason (2003) this admirable philosopher of science administers a dose of intellectual sanity and moderation, steering a course between The New Cynics and The Old Deferentialists (always down on their knees in awe before scientific achievements). She plainly feels it is time to move on, and that the stormy 20th-century disputes about verification versus falsification, or about induction versus deduction—along with the competing extravagances of academic logicians on the one hand and politically driven sociologists of science on the other—should be expeditiously relegated to the archives.

Taking her stand as a “critical common-sensist” Haack calls for compromise and pragmatism. Like John Dewey she is more fond of the notion of inquiry than of truth, and although Dewey’s “warranted assertability” does not make a direct appearance in the argument (or not that I noticed), she gives an entire chapter to the concept of “warrant” itself. Common-sensism also maintains that “scientific inquiry is continuous with the most ordinary of everyday empirical inquiry”, and a range of opinion is marshalled to support this view.

Back in the 19th century T. H. Huxley had said that science was little more than trained and organized common sense, while Dewey wrote that “scientific subject-matter and procedures grow out of the direct problems and methods of common sense.” The Nobel-winning physicist Percy Bridgman argued that “there is no scientific method as such… the most vital feature of the scientist’s procedure has been merely to do his utmost with his mind.” For his part Einstein himself made a contribution similar to Huxley’s: “the whole of science is nothing more than a refinement of everyday thinking.”

In his usual distinguished style George Santayana wrote in Reason in Science: “Science is common knowledge extended and refined. Its validity is of the same order as that of ordinary perception, memory, and understanding. Its test is found, like theirs, in actual imitation, which sometimes consists in perception and sometimes in intent. The flight of science is merely longer from perception to perception, and its deduction more accurate from meaning to meaning and from purpose to purpose.”

* * *

All of which stands intriguingly at odds with the views of other scientists (cited in Science and the Greeks last August) who prefer to emphasize the discontinuity of science and common sense. In the opening chapter of his 1992 book The Unnatural Nature of Science (a chapter with the title “Unnatural Thoughts”) Lewis Wolpert gave this point of view perhaps its most categorical expression: “Both the ideas that science generates and the way in which science is carried out are entirely counter-intuitive and against common sense — by which I mean that scientific ideas cannot be acquired by simple inspection of phenomena and that they are very often outside everyday experience. Science does not fit with our natural expectations.”

…scientific thinking differs from everyday thinking not only in the concepts used but in what constitutes a satisfactory explanation: common sense thinking about motion, for example, is not concerned with the spelling-out in detail of the relationships between terms such as force and velocity — each involving strictly defined and quite difficult concepts — but can be satisfied with vague statements.

A further difference is the purpose behind scientific thinking and the thinking of everyday life. In everyday life one is primarily concerned with usefulness, whereas science is concerned with a rather abstract understanding.

This is exemplified by Sherlock Holmes when he turns to Watson, who has been castigating him for not knowing about Copernicus and the solar system, and says, ‘What the deuce is it to me if you say we go round the sun. If we went round the moon it would not make a pennyworth of difference to me or my work.’

In fact one of the strongest arguments for the distance between common sense and science is that the whole of science is totally irrelevant to most people’s day-to-day lives. One can live very well without knowledge of Newtonian mechanics, cell theory and DNA, and other sciences…

Doing science (in contrast to doing cooking) requires one to remove oneself from one’s personal experience and to try to understand phenomena not directly affecting one’s day-to-day life, one’s personal constructs. In everyday life one requires no construct as to why bodies fall when dropped or why children may or may not resemble their parents; it is sufficient that they do so. Common sense provides no more than some of the raw material required for scientific thinking.

‘Demarcation’ (a light digression)

Regarding Wolpert’s use of Sherlock Holmes and Doctor Watson, we might pause and note a curious feature of their altercation. When Sherlock Holmes says irritably that “If we went round the moon it would not make a pennyworth of difference to me or my work” it doesn’t take much imagination to see that as it stands, this statement is clearly false. If the earth were circling a cold and dead planetary object, and not the sun, it would make an enormous difference in fact; Holmes would have to lay in firewood till the end of time.

What would not however make the smallest difference to Holmes and his work is the mere belief that the earth and its inhabitants revolve around the moon. For the consequences of men and women having false beliefs are often negligible, whereas the consequences of different factual conditions in the external world may be immense. Numerous cultures have held numerous odd beliefs about terrestrial and planetary motion, but except for awkward mavericks like Copernicus and Galileo such notions have had no consequence in their lives whatever.

Indeed, people’s heads are full of so much inconsequential nonsense (inconsequential in the strict sense that there are no practical effects in daily life whether the ideas are true or false) that one has to work hard to contrive a test situation in which a serious human penalty must be paid for false belief. My own preferred crucial experiment involves trains. If Paul Feyerabend, for example, were to remain sitting on a railway track before an advancing locomotive in the belief that his friendly voodoo witch-doctor’s spiritual powers could bring the train to a halt…

Need I say more? Even if we picture a thousand Feyerabendian witchdoctors joining him sitting on the rails, confident of the outcome, all zealously chanting together —

If you do voodoo
Like I do voodoo
We’ll stop that train
In its tracks

I find it hard to think the issue would be seriously in doubt. Despite their most powerful spells, despite their most deeply held beliefs, the whole bunch would be swept away in one mighty epistemological stroke.

Much weighty stuff has been written about the difficulties of drawing a clear line between science and superstition, most of it written by philosophers. For the most part, however, scientists themselves have no difficulty telling what is and what isn’t science. In Alan Cromer’s words in his book Uncommon Sense, “parity violation is, but extrasensory perception is not. Cosmology is, but channelling is not. Quantum mechanics is, but chiropractic is not.” Yet for some reason philosophers of science find this distinction much harder to make.

The Train Test can be seen as a rough and ready contribution to solving this “demarcation dispute.” Anyone can see that for Professor Feyerabend to save himself he would need to draw a clear and decisive line between, on the one hand, the unempirical voodoo prophecy he has publicly endorsed, and a scientific prediction on the other, fortified by Newtonian mechanics, that dooms him to instant annihilation. How that clear and decisive line should be defined may safely be left to philosophers. They enjoy playing with words, grammar, and logical puzzles. Scientists themselves are less interested in such things.

For millions of years variations of the Train Test eliminated cognitive delusion among living things. The ant that thought ant-lions were friendly didn’t last long. The calf that mistook an approaching tiger for a cow was eaten. The herring that believed a shark was just a big herring like itself ended up inside it. Only with the rise of the vast protective apparatus of human culture has it been possible for one animal, homo sapiens, to entertain entirely false ideas about its surroundings and not be punished.

There is of course a lot of truth in Haack’s view that science and ordinary inquiry share much in common, and that most day-to-day human thinking seeks to correct error. But cultures also indulge and accommodate cognitive nonsense by the ton—especially primitive cultures—and for the most part this has no observable social effect. If you secretly believe the moon is made of cheese and inhabited by little green men, no serious price need be paid. No punishment is ordained for such ideas, nor will holding them shorten your life. All over the world millions of people believe sillier things and survive.

Consensibility and consensuality

Scientists differ from the generality of mankind in that combating cognitive nonsense is both their special interest and their skill. One aspect of this Darwinian culling is anonymous peer review as conducted by scientific journals—the process that caught Einstein and Rosen in a mistake.

But peer review is just part of an extensive formal and informal social apparatus to spot mistakes, confirm hypotheses, and verify experimental results. This apparatus exists to ensure that whatever the subject, and however difficult the research, the largest possible number of men and women studying it are able finally to agree. As the distinguished physicist and science writer John Ziman says in his book Reliable Knowledge, “the goal of science is a consensus of rational opinion over the widest possible field.”

What happens when the consensus is wrong? Put most simply, work continues until the mistake is corrected. In any case, as Steven Weinberg says of physics in Facing Up: Science and its Cultural Adversaries (2001), even when there are shaky elements in the generally-agreed-upon picture of things, the consensus in the last hundred years “has never been simply wrong.” No consensus in the physics community “has ever been simply a mistake, in the way that in earlier centuries you might say, for example, that the theory of caloric or phlogiston was a mistake.” The consensus provides a good initial approximation; it is then adjusted to include necessary corrections researchers had not properly understood before.

Postmodern critics who sociologize science as “social construction” ludicrously exaggerate the role of hegemonic groups whose sinister influence supposedly controls events. In fact, writes Weinberg, “the exact sciences show a remarkable measure of resilience and resistance to any kind of hegemonic influence, perhaps more than any other human enterprise.”

The working philosophy of most scientists is that there is an objective reality and that, despite many social influences, the dominant influence in the history of science is the approach to that objective reality…

I think we scientists need make no apologies. It seems to me that our science is a good model for intellectual activity. We believe in an objective truth that can be known, and at the same time we are always willing to reconsider, as we may be forced to, what we have previously accepted. This would not be a bad ideal for intellectual life of all sorts.

* * *

Error-correction along the path to consensus imposes certain requirements on scientific communication. It must be what Ziman calls “consensible”—in other words (and there are echoes of Popper’s falsifiability criterion here) scientific propositions must be sufficiently free of obscurity and ambiguity to enable researchers either to agree with them, or to offer solid objections. Consensibility denotes a potentiality; consensuality, on the other hand, is an ideal outcome. “We may say that consensibility is a necessary condition for any scientific communication, whereas only a small proportion of the whole body of science is undeniably consensual at a given moment.”

Like democratic politics, which in some ways it resembles, scientific research is a social activity. This is essential. As Ziman wrote in his 1968 book Public Knowledge:

The scientific enterprise is corporate… It is never one individual that goes through all the steps in the logico-deductive chain; it is a group of individuals, dividing their labour but continuously and jealously checking each other’s contributions.

The cliché of scientific prose betrays itself: “Hence we arrive at the conclusion that…” The audience to which scientific publications are addressed is not passive; by its cheering or booing, its bouquets and brickbats, it actively controls the substance of the communications that it receives.

* * *

Zircon crystals are currently under investigation, and in this case researchers are being gratifyingly showered with bouquets. They have collectively arrived at the conclusion that the age and composition of the crystals can mean only one thing: that while the earth may just possibly have been a fiery hell incompatible with life 4.5 billion years ago, there’s a good chance that it was already rather cool and watery only 100 million years later—much earlier than expected.

The report in October’s Scientific American tells how the research has involved ground-level geology in Western Australia, fossicking in the Jack Hills 800 miles north of the city of Perth. Tiny barely visible grains are all there is to work with (though they come from bigger rocks that are yet to be found), and the process by which these are dated is set out, along with the Scientific American’s usual superb illustrations, by principal investigator John W. Valley. Valley’s dating of the crystals was made possible by earlier work by William Compston at the Australian National University, whose group invented an instrument called the Sensitive High-Resolution Ion Micro Probe. A one-time doctoral student of Valley’s at Colgate University was also involved.

Visits to other researchers at the University of Edinburgh confirmed that the zircon crystals (because of their high oxygen isotope ratios) must have formed in an environment of liquid water and low temperatures, with a climate “more like a sauna than a Hadean fireball.” More and more men and women are working internationally on zircon-dating and related matters, in Perth, Canberra, Beijing, Los Angeles, Edinburgh, Stockholm, and in Nancy, France; tens of thousands of crystals have been fed into ion microprobes; and as this growing army of investigators arrive at a consensus regarding the age of these tiny bits of mineral, publishing refereed papers in journals worldwide—“continuously and jealously checking each other’s contributions”, as Ziman says—the picture of our early world is changing.

Progress in science

Progress in science is difficult, mistakes are made, careers go up and down and some are ruined. Pioneers like Wegener with his theory of continental drift may face stiff opposition that takes decades to overcome. Yet the edifice of science is something far grander and nobler than any New Cynic will ever understand. It is also of central importance for a humane and reasonable civilization. Science is one of those areas of human activity where disagreement does not lead to bomb-throwing or blowing other people up. But since the late John Ziman (who died in January 2005), a notable physicist in his day and a Fellow of the Royal Society, has already expressed these matters more eloquently and with rather more authority than myself, I shall close by quoting from the chapter “Dissent and Selection” in his book:

Experienced scientists know that real progress in research is slow and painful, and that many experimental observations and plausible arguments will not stand up for long under expert questioning. If science is to evolve, it must continually purge itself of misconceptions, follies, and practical errors: there must be preserved a central store of absolutely reliable knowledge, from which to draw in evaluating novel ideas and on which, very slowly and carefully, to build. In order that science may retain its reliability and credibility, each scientist is expected to exercise critical vigilance over his own work and the claims of his contemporaries…

The facts demonstrate that a healthy scientific community can accommodate intellectual controversy without breaking down. Consider, for example, the history of Wegener’s hypothesis of continental drift. Here was an immense revolution of thought, grossly overdue despite the almost pathological conservatism that had to be overcome by its advocates. Yet by the standards of most human institutions, academic as well as overtly political, it was a very gentlemanly affair, in which the evolution of scientific knowledge was not disgraced by silenced voices or broken heads.

Although the majority of the leading geologists of the time were unconvinced by Wegener’s theory, and no doubt cautioned their students against it, it was not suppressed and forbidden as ‘heresy’. There were several set-piece public debates and conferences on the subject, and books and papers supporting Wegener’s interpretation continued to be published. It is likely that some of the protagonists did not fare quite so well in their academic careers as hindsight would now consider deserving; but when, eventually, new evidence from rock magnetism vindicated Wegener’s bold and imaginative hypothesis, the ‘old gang’ were not swept into scholarly oblivion by the ‘revolutionary’ supporters of the new orthodoxy of plate tectonics.

This truly remarkable and civilized behavior amongst scientists we take for granted: these are the standards against which occasional pathologies are judged. And if those who rule society—aristocrats or democrats, capitalists or socialists, conservatives or radicals—want scientific knowledge on which they can rely, they must not allow the inner tension of science to slacken, break, or overbalance.

According to the narrow logic of bureaucratic planning, it is a wasteful, irrational system that ought to be made efficient and economical. But by encouraging innovation, yet conserving past achievement, by calling the gambling competitive spirit from each of us, yet making us also the guardians of truth and the judges of quality, it is remarkably successful as the source of many wonders.

John Ziman, Reliable Knowledge

Posted in Science.