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Revision as of 23:16, 6 February 2005 by JonGwynne (talk | contribs) (The answer to your question William is: "not you")(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)The concept of scientific consensus is a controversial subject, and the term itself is defined variously by several factions particularly in debates over public policy.
Lack of substantial doubt
In its strongest form, the term is used to assert that on a given question scientists within a particular field of science have reached an agreement of rational opinion without substantial doubt, through a process of experimentation and peer review (see scientific method).
For example, in physics there exists scientific consensus on general relativity and quantum mechanics. Special relativity and quantum mechanics are unified in the framework of quantum field theory (QFT). There exists scientific consensus that QFT is a very useful description, but it is not a final theory. For example, it does not include gravity. General relativity and quantum mechanics may be unified by superstring theory but there is no consensus whether this candidate unifying theory is the correct description of reality.
Relation to validity
In public policy debates, the assertion that there exists a consensus of scientists is often used as an argument for the validity of a theory. The best-known instances are found in the debates over teaching evolution in public schools, and the furor of the global warming theory.
Surveys of scientists show that 99.8% of biologists accept the naturalistic theory of evolution (i.e., some form of the neo-Darwinian synthesis) while about 5% of scientists in general reject or question the theory. This is an instance of of a scientific hypotheses in one field enjoying significantly less acceptance by scientists from other fields. Nonetheless, proponents of evolution appeal to the near-unanimity of scientific thought on evolution as a good reason to use the clout of American public schools to endorse it (see evolution controversy).
It is typically argued that climate scientists are in substantial agreement about global warming. Some refer to this literally as a "scientific consensus", while others use different words; generally the reports of the United Nations' panel on climate change (IPCC) are considered to amount to scientifec consensus on the issue.
Other meanings
The term is sometimes used to refer to a general consensus of agreement within the wider scientific community (compare "consensus science").
How consensus can change over time
Scientific consensus is continually evolving as new evidence contradicts existing theories and new hypothesis are presented.
Whilst consensus exists in a wide range of scientific fields there exist objectors to all these theories - consensus means overwhelming support, not total agreement.
One mark of the consensus is that it is the theory against which all challengers must be compared.
In the case of relativity and quantum mechanics, the expectation is that these theories will be replaced by a Grand Unification Theory. There are candidates, but there is certainly no consensus on a suitable candidate as a unifying theory. Nor does consensus mean that the theory is fully understood - there remain problems with the interpretation of the meaning of quantum mechanics, for examples, even though its predictions are precise.
Formerly, there was a consensus that Newtonian gravity was correct, in part because its predictions were extremely good. Over time, various objections to the theory mounted. One in particular was the precession of the perihelion of the orbit of Mercury. However, despite increasingly clear observations of an anomaly, and the failure of various attempts to explain it away, the failure to of the theory to match observations was not considered the death knell of the theory. Today, the scientific consensus is that the Newtonian gravity is just a very useful approximation of general relativity which itself may be superseded by a more complete theory sometime in the future.
Scientific consensus and the scientific minority
In a standard application of the psychological principle of confirmation bias, 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 divergence away from correct ideas and toward incorrect ideas. 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 in his 1962 book The Structure of Scientific Revolutions discussed this problem in detail.
Several examples of this are present in the relatively recent history of science. For example:
- the theory of symbiogenesis presented by Lynn Margulis and initially rejected by biologists but now generally accepted.
- the theory of punctuated equilibria proposed by Stephen Gould and Niles Eldredge which is still debated but becoming more accepted in evolutionary theory.
In 1990, Dr. Richard Lindzen of MIT wrote an article for the American Meteorological Society in which he denounced the recommendation "that skepticism be stifled" with regard to the issues surrounding the question of global warming.