Scientific consensus is the collective judgment, position, and opinion of the vast majority of active, qualified experts on a conclusion in a specific scientific discipline. Scientific consensus results from the self-correcting scientific process of peer review, replication of the event through the scientific method, scholarly debate, meta-analysis, and publication of high-quality review articles, monographs, or guidelines in reputable books and journals to establish facts and durable knowledge about the topic.
Reaching consensus requires significant scientific agreement among qualified experts, a process based on scientific substantiation of a claim that meets the burden of proof by proposing a possible cause-and-effect mechanism supported by the totality of evidence, leading to agreement among experts. In many countries, scientific consensus established on significant scientific agreement is the basis for regulatory approval of drugs to specify a health claim for the properties of the approved therapeutic agent. A conference meant to create a consensus is called a consensus conference. Such measures within a discipline can establish a consensus, although communicating to the lay public that consensus exists may be difficult because the "normal" debates toward gaining consensus may appear to outsiders as revealing uncertainty.
Scientific substantiation
Scientific substantiation for any specific claim is the result of competent and reliable scientific evidence meeting the burden of proof, such as for the confirmed functions of food nutrients on body functions, child growth and development, and reduction of disease risk factors. and by Health Canada.
For health claims associated with dietary supplements, the US Food and Drug Administration (FDA) and Federal Trade Commission (FTC) have a "substantiation standard" defined as "tests, analyses, research, studies, or other evidence based on the expertise of professionals in the relevant area, that has been conducted and evaluated in an objective manner by persons qualified to do so, using procedures generally accepted in the profession to yield accurate and reliable results." Supplement labeling requires manufacturers to have substantiation for each claim using a standard consistent with the FTC definition of "competent and reliable scientific evidence". EFSA committees and panels report the results of the collective scientific assessments of foods and supplements for safety and efficacy, with each member having equal input and no one member dominating committee decisions. the European Union, Japan, and United States,
Position statements
thumb|Scientific consensus among publishing [[Climatology|climatologists on human-caused global warming (as of 2021)]]
On occasion, medical organizations or scientific institutes issue position statements, consensus review articles or surveys intended to communicate the science from "inside" the expert source to the "outside" of the scientific community. In cases where there is little controversy regarding the subject under study, such as the human causes of climate change, establishing the consensus is straightforward. climate change, or the lack of causality between MMR vaccinations and autism.
Change of consensus 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 the 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. Karl Popper proposed that since no amount of experiments could ever prove a scientific theory, but a single experiment could disprove one, science should be based on falsification. Whilst this forms a logical theory for science, it is in a sense "timeless" and does not necessarily reflect a view on how science should progress over time.
Among the most influential challengers of this approach was Thomas 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 "paradigms", 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 series of paradigm shifts 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. Studies from 2019 to 2021 found scientific consensus to range from 98.7 to 100%.]]
Perception of whether a scientific consensus exists on a given issue, and how strong that conception is, has been described as a "gateway belief" upon which other beliefs and then action are based.
Politicization of science
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. Similarly arguments for a lack of scientific consensus are often used to support doubt about the theory.
For example, the scientific consensus on the causes of global warming is that global surface temperatures have increased in recent decades and that the trend is caused primarily by human-induced emissions of greenhouse gases. The historian of science Naomi Oreskes published an article in Science 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. Oreskes's findings were replicated by other methods that require no interpretation. Opponents of evolution claim that there is significant dissent on evolution within the scientific community. The wedge strategy, a plan to promote intelligent design, depended greatly on seeding and building on public perceptions of absence of consensus on evolution.
The inherent uncertainty in science, where theories are never proven but can only be disproven (see falsifiability), 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'.