Scientific consensus

Scientific consensus

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Scientific consensus is the collective judgment, position, and opinion
Opinion
In general, an opinion is a subjective belief, and is the result of emotion or interpretation of facts. An opinion may be supported by an argument, although people may draw opposing opinions from the same set of facts. Opinions rarely change without new arguments being presented...

 of the community
Scientific community
The scientific community consists of the total body of scientists, its relationships and interactions. It is normally divided into "sub-communities" each working on a particular field within science. Objectivity is expected to be achieved by the scientific method...

 of scientist
Scientist
A scientist in a broad sense is one engaging in a systematic activity to acquire knowledge. In a more restricted sense, a scientist is an individual who uses the scientific method. The person may be an expert in one or more areas of science. This article focuses on the more restricted use of the word...

s in a particular field of study. Consensus implies general agreement, though not necessarily unanimity
Unanimity
Unanimity is agreement by all people in a given situation. When unanimous, everybody is of the same mind and acting together as one. Though unlike uniformity, it does not constitute absolute agreement. Many groups consider unanimous decisions a sign of agreement, solidarity, and unity...

. Scientific consensus is not by itself a scientific argument, and it is not part of the scientific method
Scientific method
Scientific method refers to a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed scientific, a method of inquiry must be based on gathering empirical and measurable evidence subject to specific principles of...

. Nevertheless, consensus may be based on both scientific arguments and the scientific method.

Consensus is normally achieved through communication at conferences, the publication process, replication (reproducible results by others) and peer review
Peer review
Peer review is a process of self-regulation by a profession or a process of evaluation involving qualified individuals within the relevant field. Peer review methods are employed to maintain standards, improve performance and provide credibility...

. These lead to a situation in which those within the discipline can often recognize such a consensus where it exists, but communicating to outsiders that consensus has been reached can be difficult, because the 'normal' debates through which science progresses may seem to outsiders as contestation. On occasion, scientific institutes issue position statements intended to communicate a summary of the science from the "inside" to the "outside" of the scientific community. In cases where there is little controversy regarding the subject under study, establishing what the consensus is can be quite straightforward.

Scientific consensus may be invoked in popular or political debate on subjects that are controversial within the public sphere but which may not be controversial within the scientific community, such as evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

 or the claimed linkage of MMR vaccinations and autism
MMR vaccine controversy
The MMR vaccine controversy was a case of scientific misconduct which triggered a health scare. It followed the publication in 1998 of a paper in the medical journal The Lancet which presented apparent evidence that autism spectrum disorders could be caused by the MMR vaccine, an immunization...

.

How consensus can change over time



There are many philosophical and historical theories as to how scientific consensus changes over time. Because the history of scientific change is extremely complicated, and because there is a tendency to project "winners" and "losers" onto the past in relation to our current scientific consensus, it is very difficult to come up with accurate and rigorous models for scientific change. This is made exceedingly difficult also in part because each of the various branches of science functions in somewhat different ways with different forms of evidence and experimental approaches.

Most models of scientific change rely on new data produced by scientific experiment
Experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...

. The philosopher Karl Popper
Karl Popper
Sir Karl Raimund Popper, CH FRS FBA was an Austro-British philosopher and a professor at the London School of Economics...

 proposed that since no amount of experiments could ever prove a scientific theory, but a single experiment could disprove one, all scientific progress should be based on a process of falsification
Falsifiability
Falsifiability or refutability of an assertion, hypothesis or theory is the logical possibility that it can be contradicted by an observation or the outcome of a physical experiment...

, where experiments are designed with the hope of finding empirical data that the current theory could not account for, indicating its falseness and the requirement for a new theory.

Among the most influential challengers of this approach was the historian Thomas Kuhn
Thomas Kuhn
Thomas Samuel Kuhn was an American historian and philosopher of science whose controversial 1962 book The Structure of Scientific Revolutions was deeply influential in both academic and popular circles, introducing the term "paradigm shift," which has since become an English-language staple.Kuhn...

, who argued instead that experimental data always provide some data which cannot fit completely into a theory, and that falsification alone did not result in scientific change or an undermining of scientific consensus. He proposed that scientific consensus worked in the form of "paradigm
Paradigm
The word paradigm has been used in science to describe distinct concepts. It comes from Greek "παράδειγμα" , "pattern, example, sample" from the verb "παραδείκνυμι" , "exhibit, represent, expose" and that from "παρά" , "beside, beyond" + "δείκνυμι" , "to show, to point out".The original Greek...

s", which were interconnected theories and underlying assumptions about the nature of the theory itself which connected various researchers in a given field. Kuhn argued that only after the accumulation of many "significant" anomalies would scientific consensus enter a period of "crisis". At this point, new theories would be sought out, and eventually one paradigm would triumph over the old one — a cycle of paradigm shift
Paradigm shift
A Paradigm shift is, according to Thomas Kuhn in his influential book The Structure of Scientific Revolutions , a change in the basic assumptions, or paradigms, within the ruling theory of science...

s rather than a linear progression towards truth. Kuhn's model also emphasized more clearly the social and personal aspects of theory change, demonstrating through historical examples that scientific consensus was never truly a matter of pure logic or pure facts. However, these periods of 'normal' and 'crisis' science are not mutually exclusive. Research shows that these are different modes of practice, more than different historical periods.

Lastly, some more radical philosophers, such as Paul Feyerabend
Paul Feyerabend
Paul Karl Feyerabend was an Austrian-born philosopher of science best known for his work as a professor of philosophy at the University of California, Berkeley, where he worked for three decades . He lived a peripatetic life, living at various times in England, the United States, New Zealand,...

, have maintained that scientific consensus is purely idiosyncratic and maintains no relationship to any outside truth. These points of view, while provoking much discussion, have generally not caught on, even with philosophers.

Scientific consensus and the scientific minority


In a standard application of the psychological principle of confirmation bias
Confirmation bias
Confirmation bias is a tendency for people to favor information that confirms their preconceptions or hypotheses regardless of whether the information is true.David Perkins, a geneticist, coined the term "myside bias" referring to a preference for "my" side of an issue...

, scientific research which supports the existing scientific consensus is usually more favorably received than research which contradicts the existing consensus. In some cases, those who question the current paradigm are at times heavily criticized for their assessments. Research which questions a well supported scientific theory is usually more closely scrutinized in order to assess whether it is well researched and carefully documented. This caution and careful scrutiny is used to ensure that science is protected from a premature divergence away from ideas supported by extensive research and toward new ideas which have yet to stand the testing by extensive research. However, this often results in conflict between the supporters of new ideas and supporters of more dominant ideas, both in cases where the new idea is later accepted and in cases where it is later abandoned.

Thomas Kuhn
Thomas Kuhn
Thomas Samuel Kuhn was an American historian and philosopher of science whose controversial 1962 book The Structure of Scientific Revolutions was deeply influential in both academic and popular circles, introducing the term "paradigm shift," which has since become an English-language staple.Kuhn...

 in his 1962 book
Book
A book is a set or collection of written, printed, illustrated, or blank sheets, made of hot lava, paper, parchment, or other materials, usually fastened together to hinge at one side. A single sheet within a book is called a leaf or leaflet, and each side of a leaf is called a page...

 The Structure of Scientific Revolutions
The Structure of Scientific Revolutions
The Structure of Scientific Revolutions , by Thomas Kuhn, is an analysis of the history of science. Its publication was a landmark event in the history, philosophy, and sociology of scientific knowledge and it triggered an ongoing worldwide assessment and reaction in — and beyond — those scholarly...

discussed this problem in detail. Several examples of new concepts gaining acceptance when supported by accumulating evidence are present in the relatively recent history of science
History of science
The history of science is the study of the historical development of human understandings of the natural world and the domains of the social sciences....

. For example:
  • the theory of continental drift
    Continental drift
    Continental drift is the movement of the Earth's continents relative to each other. The hypothesis that continents 'drift' was first put forward by Abraham Ortelius in 1596 and was fully developed by Alfred Wegener in 1912...

     proposed by Alfred Wegener
    Alfred Wegener
    Alfred Lothar Wegener was a German scientist, geophysicist, and meteorologist.He is most notable for his theory of continental drift , proposed in 1912, which hypothesized that the continents were slowly drifting around the Earth...

     and supported by Alexander Du Toit
    Alexander Du Toit
    Alexander Logie du Toit was a geologist from South Africa, and an early supporter of Alfred Wegener's theory of continental drift.Born in Newlands, Cape Town in 1878, du Toit was educated at the Diocesan College in Rondebosch and the University of the Cape of Good Hope...

     and Arthur Holmes
    Arthur Holmes
    Arthur Holmes was a British geologist. As a child he lived in Low Fell, Gateshead and attended the Gateshead Higher Grade School .-Age of the earth:...

     but soundly rejected by most geologists until indisputable evidence and an acceptable mechanism was presented after 50 years of rejection.
  • the theory of symbiogenesis
    Symbiogenesis
    Symbiogenesis is the merging of two separate organisms to form a single new organism. The idea originated with Konstantin Mereschkowsky in his 1926 book Symbiogenesis and the Origin of Species, which proposed that chloroplasts originate from cyanobacteria captured by a protozoan...

     presented by Lynn Margulis
    Lynn Margulis
    Lynn Margulis was an American biologist and University Professor in the Department of Geosciences at the University of Massachusetts Amherst. She is best known for her theory on the origin of eukaryotic organelles, and her contributions to the endosymbiotic theory, which is now generally accepted...

     and initially rejected by biologists but now generally accepted.
  • the theory of punctuated equilibria proposed by Stephen Jay Gould
    Stephen Jay Gould
    Stephen Jay Gould was an American paleontologist, evolutionary biologist, and historian of science. He was also one of the most influential and widely read writers of popular science of his generation....

     and Niles Eldredge
    Niles Eldredge
    Niles Eldredge is an American paleontologist, who, along with Stephen Jay Gould, proposed the theory of punctuated equilibrium in 1972.-Education:...

     which is still debated but becoming more accepted in evolutionary theory.
  • the theory of prion
    Prion
    A prion is an infectious agent composed of protein in a misfolded form. This is in contrast to all other known infectious agents which must contain nucleic acids . The word prion, coined in 1982 by Stanley B. Prusiner, is a portmanteau derived from the words protein and infection...

    s—proteinaceous infectious particles causing transmissible spongiform encephalopathy
    Transmissible spongiform encephalopathy
    Transmissible spongiform encephalopathies , also known as prion diseases, are a group of progressive conditions that affect the brain and nervous system of many animals, including humans. According to the most widespread hypothesis they are transmitted by prions, though some other data suggest an...

     diseases—proposed by Stanley B. Prusiner
    Stanley B. Prusiner
    Stanley Ben Prusiner is an American neurologist and biochemist. Currently the director of the Institute for Neurodegenerative Diseases at University of California, San Francisco . Prusiner discovered prions, a class of infectious self-reproducing pathogens primarily or solely composed of protein...

     and at first rejected because pathogenicity was believed to depend on nucleic acid
    Nucleic acid
    Nucleic acids are biological molecules essential for life, and include DNA and RNA . Together with proteins, nucleic acids make up the most important macromolecules; each is found in abundance in all living things, where they function in encoding, transmitting and expressing genetic information...

    s now widely accepted due to accumulating evidence.
  • the theory of Helicobacter pylori
    Helicobacter pylori
    Helicobacter pylori , previously named Campylobacter pyloridis, is a Gram-negative, microaerophilic bacterium found in the stomach. It was identified in 1982 by Barry Marshall and Robin Warren, who found that it was present in patients with chronic gastritis and gastric ulcers, conditions that were...

    as the cause of stomach ulcers. This theory was first postulated in 1982 by Barry Marshall
    Barry Marshall
    Barry James Marshall, AC, FRS, FAA is an Australian physician, Nobel Prize laureate in Physiology or Medicine, and Professor of Clinical Microbiology at the University of Western Australia. Marshall is well-known for proving that the bacterium Helicobacter pylori Barry James Marshall, AC, FRS, FAA...

     and Robin Warren
    Robin Warren
    John Robin Warren AC is an Australian pathologist, Nobel Laureate and researcher who is credited with the 1979 re-discovery of the bacterium Helicobacter pylori, together with Barry Marshall.- Life and career :...

     but was widely rejected by the medical community which believed that no bacterium could survive for long in the acidic environment of the stomach. Marshall demonstrated his findings by drinking a brew of the bacteria and consequently developing ulcers, subsequently curing himself with antibiotic medication. In 2005, Warren and Marshall were awarded the Nobel Prize in Medicine for their work on H. pylori


For every new idea that has gained acceptance, there are many more examples of new ideas that were shown to be wrong. Two of the classics are N rays and polywater
Polywater
Polywater was a hypothetical polymerized form of water that was the subject of much scientific controversy during the late 1960s. By 1969 the popular press had taken notice, and by 1970 doubts about its authenticity were being circulated. By 1973 it was found to be illusory...

.

Uncertainty and scientific consensus in policy making


In public policy debates, the assertion that there exists a consensus of scientists in a particular field is often used as an argument for the validity of a theory and as support for a course of action by those who stand to gain from a policy based on that consensus. Similarly arguments for a lack of scientific consensus are often encouraged by sides who stand to gain from a more ambiguous policy.

People of various backgrounds (political, scientific, media, action groups, and so on) have argued that there is a scientific consensus on the causes of global warming
Scientific opinion on climate change
The predominant scientific opinion on climate change is that the Earth is in an ongoing phase of global warming primarily caused by an enhanced greenhouse effect due to the anthropogenic release of carbon dioxide and other greenhouse gases...

. The historian of science
History of science and technology
The history of science and technology is a field of history which examines how humanity's understanding of the natural world and ability to manipulate it have changed over the centuries...

 Naomi Oreskes
Naomi Oreskes
Naomi Oreskes is an American science historian, and Professor of History and Science Studies at the University of California San Diego. She has worked on studies of geophysics, environmental issues such as global warming, and the history of science...

 published an article in Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....

reporting that a survey of the abstracts of 928 science articles published between 1993 and 2003 showed none which disagreed explicitly with the notion of anthropogenic global warming. In an editorial published in the Washington Post, Oreskes stated that those who opposed these scientific findings are amplifying the normal range of scientific uncertainty about any facts into an appearance that there is a great scientific disagreement, or a lack of scientific consensus. Oreskes's findings were replicated by other methods that require no interpretation.

The theory of evolution through natural selection
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

 is an accepted part of the science of biology, to the extent that few observations in biology can be understood without reference to natural selection and common descent. Opponents of evolution claim that there is significant dissent on evolution within the scientific community. The wedge strategy
Wedge strategy
The wedge strategy is a political and social action plan authored by the Discovery Institute, the hub of the intelligent design movement. The strategy was put forth in a Discovery Institute manifesto known as the Wedge Document, which describes a broad social, political, and academic agenda whose...

, an ambitious plan to supplant scientific materialism
Naturalism (philosophy)
Naturalism commonly refers to the philosophical viewpoint that the natural universe and its natural laws and forces operate in the universe, and that nothing exists beyond the natural universe or, if it does, it does not affect the natural universe that we know...

 seen as inimical to religion, with a religion-friendly theistic science, depended greatly on seeding and building on public perceptions of absence of consensus on evolution. Stephen Jay Gould
Stephen Jay Gould
Stephen Jay Gould was an American paleontologist, evolutionary biologist, and historian of science. He was also one of the most influential and widely read writers of popular science of his generation....

 has argued that creationists misunderstand the nature of the debate within the scientific community, which is not about "if" evolution occurred, but "how" it occurred.

The inherent uncertainty in science, where theories are never proven but can only be disproven (see falsifiability
Falsifiability
Falsifiability or refutability of an assertion, hypothesis or theory is the logical possibility that it can be contradicted by an observation or the outcome of a physical experiment...

), poses a problem for politicians, policymakers, lawyers, and business professionals. Where scientific or philosophical questions can often languish in uncertainty for decades within their disciplinary settings, policymakers are faced with the problems of making sound decisions based on the currently available data, even if it is likely not a final form of the "truth". The tricky part is discerning what is close enough to "final truth". For example, social action against smoking probably came too long after science was 'pretty consensual'.

Certain domains, such as the approval of certain technologies for public consumption, can have vast and far-reaching political, economic, and human effects should things run awry of the predictions of scientists. However, insofar as there is an expectation that policy in a given field reflect knowable and pertinent data and well-accepted models of the relationships between observable phenomena, there is little good alternative for policy makers than to rely on so much of what may fairly be called 'the scientific consensus' in guiding policy design and implementation, at least in circumstances where the need for policy intervention is compelling. While science cannot supply 'absolute truth' (or even its complement 'absolute error') its utility is bound up with the capacity to guide policy in the direction of increased public good and away from public harm. Seen in this way, the demand that policy rely only on what is proven to be "scientific truth" would be a prescription for policy paralysis and amount in practice to advocacy of acceptance of all of the quantified and unquantified costs and risks associated with policy inaction. Such considerations informed the development of 'the precautionary principle
Precautionary principle
The precautionary principle or precautionary approach states that if an action or policy has a suspected risk of causing harm to the public or to the environment, in the absence of scientific consensus that the action or policy is harmful, the burden of proof that it is not harmful falls on those...

'.

No part of policy formation on the basis of the ostensible scientific consensus precludes persistent review either of the relevant scientific consensus or the tangible results of policy. Indeed, the same reasons that drove reliance upon the consensus drives the continued evaluation of this reliance over time—and adjusting policy as needed.

See also

  • Appeal to authority
  • Consensus (medical)
    Consensus (medical)
    Medical consensus is a public statement on a particular aspect of medical knowledge available at the time it was written, and that is generally agreed upon as the evidence-based, state-of-the-art knowledge by a representative group of experts in that area...

  • CUDOS
  • Empiricism
    Empiricism
    Empiricism is a theory of knowledge that asserts that knowledge comes only or primarily via sensory experience. One of several views of epistemology, the study of human knowledge, along with rationalism, idealism and historicism, empiricism emphasizes the role of experience and evidence,...

  • Paradigm
    Paradigm
    The word paradigm has been used in science to describe distinct concepts. It comes from Greek "παράδειγμα" , "pattern, example, sample" from the verb "παραδείκνυμι" , "exhibit, represent, expose" and that from "παρά" , "beside, beyond" + "δείκνυμι" , "to show, to point out".The original Greek...