Wednesday, June 4, 2014

Scientific Consensus: Blessing or Curse?

In a previous post called, “The Myth of the Scientific Method,” I explored how science gets accomplished in real life by describing the knowledge filter. This doesn’t mean to imply that the filter is a perfect or even preferable method of distilling knowledge into truth. Biases may still survive even at the most refined levels.
In science, new claims are constantly appraised in the light of existent knowledge, by fallible human beings organized in particular ways. Thus scientific knowledge is only an imperfect map of the actual world, imperfect because
  • existent knowledge may be misleading, particularly where striking novelties are concerned;
  • individual human beings cannot be entirely objective; and
  • collective human institutions work imperfectly.1
An undergraduate biochemistry textbook may still mention that dietary saturated fats are harmful to humans because it is known that they lead to heart disease even if the mechanisms to backup such a claim in that very textbook are unspecified. The assumed “truth” of artery clogging saturated fats is such a strongly held belief that the context of the evidence is bent to fit the consensus of the existing body of knowledge.
The knowledge filter produces consensual knowledge, which is not the same thing as objective knowledge. Nevertheless, the scientific community’s views are constrained by what experience has already shown can happen and by what cannot happen: the maps against which claims of new exploration are judged do usually reflect something of the actual landscape. According to the myth of the scientific method, scientific claims are directly tested against reality; under the puzzle and filter analogy, claims are still tested against reality, it is just that the testing is somewhat indirect.2
One might wonder if objective truth is even possible under the reins of such fallible beings as humans. The saving grace of scientific exploration is the ability to verify hypotheses against the unbending will of nature. No matter our opinion on gravity, objects will fall consistently when dropped under the same circumstances. Scientists have no veto power over reality.
Science remains the study of nature; rational opinion finds science the more satisfactory the more it properly reflects what nature does. The consensus of the scientific community—the consensus of rational opinion formed as widely as possible, as John Ziman puts it—is exceedingly sensitive to the test of nature. In Richard Burian’s happily chosen phrase, scientists make liberal use of “reality therapy.” Perpetual-motion machines are believed to be impossible because, no matter how ingeniously designed, they have never worked—period; pigs do not fly—period; there is no element of atomic number between that of hydrogen and that of helium—period; and so on and so forth. Our explanations for those truths may have little warrant, and the explanations we use do change from time to time. But that human interpretation of nature is always subject to change does not entail that human knowledge of nature’s phenomena is always fragile: maps can be crude or flawed and yet perfectly reliable in important respects.3
The universe of Aristotle and Ptolemy does not hold up to modern evidence. However, the heavens fashioned as 55 concentric, crystalline spheres that were attached to circles called epicycles provided a working model. (In some cases, epicycles were themselves placed on epicycles!) This unnecessary complexity was a result of underlying “truths” of the universe that were considered sacrosanct:
  1. All motion in the heavens is uniform circular motion.
  2. The objects in the heavens are made from perfect material, and cannot change their intrinsic properties (e.g., their brightness).
  3. The Earth is at the center of the Universe.
These assumptions no longer exist not because we as a society simply decided one day to be contrarians. The constraints of reality, in part, forced us to eventually reevaluate our beliefs. The imagination of humans may be boundless, but we are still limited to what can be evidenced by science.
…nature does still constrain observation and experiment and thereby also interpretation (or theory, or scientific belief). It does so less directly, less precisely, less automatically, and less quickly than is envisaged in the classical formulations of the scientific method; nevertheless, nature cannot but remain the ultimate and entirely firm arbiter.4
Part of the reason false ideas remain for so long is due to a lack of diversity. Evidence should come from many different sources and areas of study. The age of the Earth, for example, does not rely on carbon-14 dating alone. Even if we were to discover today that this method of measurement to be unreliable, it would not automatically invalidate all of the other avenues of evidence that helped scientists arrive at its consensus. Conversely, a lack of evidence from different aspects of nature may result in groupthink to persist.
Criticism from colleagues or peers compensates for the human inability to be skeptical about one’s own beliefs and to be aware of one’s own biases. But if one belongs to a rather homogeneous community, particularly if it is a small one, then the potential critics may share one’s own beliefs and biases. Whole groups of people may then fall into error for longer or shorter periods of time.

Homogeneity and isolation may exist for reasons of scientific history or reasons outside science. It is well known that scientific specialization involves a degree of isolation: separate societies and journals are founded to cater to increasingly specialized groups. But isolation can stem from other circumstances too: science in many countries has not shared effectively in the state-of-the-art consensus, through lack of opportunities for advanced training or for access to modern equipment, or as a result of language barriers and lack of up-to-date literature, or through politically enforced isolation. No matter what the origin of isolation or homogeneity, however, hindsight makes plain that error flourishes thereby and that stagnation is more likely than advancement.

In new subspecialties, or in old but small ones, a consensus may well be less than judicious, a fad or even a communal version of folie à deux, not much informed by reality therapy. So long as they do not need to explain themselves to outsiders, people can maintain views of the most fragile validity, about science as much as about politics or religion. But organized science nowadays comprises largely overlapping communities, and eventually consensus over the most salient things must be shared by all—they are all working the same jigsaw puzzle, albeit different parts of it.5
It’s no surprise that some of the most revolutionary work being done in nutrition is being spearheaded by relative outsiders to the field. The compartmentalized specialties of medicine do not allow much crosspollination of ideas. The backlash against much of the low carbohydrate and paleo/primal dietary advice is not based on evidence, but on entrenched scientists protecting their turf from meddlers who dare to question their authority.
The dangers of isolation or secrecy are clear. As Peter Medawar has remarked, those who shut their doors keep out more than they let out.

Historians and sociologists of science have noted many instances of discoveries made by mavericks or by people who moved from one specialty into another-people who were able to see things hidden from those steeped in the old consensus. When isolation is broken, fresh viewpoints can be remarkably illuminating. So too do experienced teachers find that students who ask naively uninformed questions can sometimes expose areas of ignorance studiously avoided by the practicing experts; for example, as I was trying to learn electrochemistry I discovered that electrochemists for several decades had used a formula based on no agreed theoretical justification and little empirical warrant.6
Scientific consensus has been portrayed as both a positive and a negative. (Usually the judgment is based on whether the person believes or disagrees with the mainstream opinion.) It’s impossible that all of the evidence is pure and that the humans doing the evaluating are impeccable. If complete objectivity, and the scientific method itself, are unobtainable goals then how can we recognize “settled science” from a consensus based on fallacy?

The answer is to keep science as open as possible so that the body of evidence for a consensus opinion can be multifaceted.
To assure that scientific knowledge is reliable, and that progress is rapid, requires that interactions among scientists be unconstrained and that scientists be as varied as possible in their biases. Science progresses through continual winnowing under consensually governed institutions. Objectivity comes into science because ideas and results are exposed to the criticism of people with disparate and conflicting and competing intellectual approaches and beliefs, personal biases, social goals, hidden agendas, and the rest, so that—by and large—consensus among all of them can only be achieved when they are left no other option than to agree with each other, when the puzzle itself demands and allows it, when the players submit jointly to reality therapy. Scientific activity therefore becomes more efficient and more reliable the more it includes the whole range of human types—geographic, sexual, intellectual, emotional—just so long as they want to learn about nature and are willing to endure the stress of reality therapy.7
If you wish to argue that a scientific theory, say evolution, is wrong then you’d better be prepared to explain how all the diverse areas of science that support that theory are off-base. Conversely, if a hypothesis based on a few lines of evidence doesn’t agree with the results from other avenues of research, then perhaps it’s time to reexamine those core beliefs. The (assumed) universal consistency of nature is one of the guiding principles of science that distinguishes it from other human practices.
…it is the only activity in which the constraints of reality have brought to the quest for deep answers an effective consensus across all the variations that in other respects divide the human species. The accepted findings of science are the same in all countries, in all languages and for people of all ages and religions and genders. Only in science has such consensus been achieved through the voluntary assent of all concerned. In other dis­ciplines, schools of thought continually dispute one another with varying degrees of intensity. In everyday political or religious affairs, consensus has not been achievable even through warfare and torture.8
Any human endeavor where consensus cannot be achieved through reality therapy cannot be considered science. This is not to say those endeavors are unimportant or inferior to science. They simply aren’t science, even if they follow (or attempt to follow) the scientific method. There is a tendency to try to claim that explorations of nature, such as folklore, religion, political ideology, or social science, are indeed science in order to achieve a level of credibility usually associated with mathematics or physics.

Let’s take the totality of what we’ve learned about how science (really) works to answer the question most of us ultimately want to know: “How authoritative or reliable is science?”
Answer: It depends whether we are talking about textbook or about frontier science. Ask the sci­entific community. If there is consensus, and if the knowledge is maturely seasoned and explicated in textbooks, then you can safely give odds of better than 10 to 1 that it is trustworthy. If it is newly minted knowledge, even if the experts are all or almost all agreed, you should not give nearly such good odds on it. And if there is no consensus, you had better act on the basis that no one really knows.9


  1. Bauer, Henry H. “Imperfections of the filter.” Scientific Literacy and the Myth of the Scientific Method. Urbana: University of Illinois Press, 1992. 88. Print.
  2. p. 88.
  3. p. 89.
  4. p. 89.
  5. p. 99.
  6. p. 101.
  7. p. 102.
  8. Bauer, Henry H. “In Praise of Science.” 143.
  9. p. 146.

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