Skeptic dictionary



Pseudoscience is defined as a body of knowledge, methodology, belief, or practice that is claimed to be scientific or made to appear scientific, but does not adhere to the scientific method, lacks supporting evidence or plausibility, or otherwise lacks scientific status. The term comes from the Greek root pseudo- (false or pretending) and "science" (from Latin scientia, meaning "knowledge"). An early recorded use was in 1843 by French physiologist François Magendie, who is considered a pioneer in experimental physiology.

As it is taught in certain introductory science classes, pseudoscience is any subject that appears superficially to be scientific or whose proponents state is scientific but nevertheless contravenes the testability requirement, or substantially deviates from other fundamental aspects of the scientific method. Professor Paul DeHart Hurd argued that a large part of gaining scientific literacy is "being able to distinguish science from pseudo-science such as astrology, quackery, the occult, and superstition". Certain introductory survey classes in science take careful pains to delineate the objections scientists and skeptics have to practices that make direct claims contradicted by the scientific discipline in question.

Beyond the initial introductory analyses offered in science classes, there is some epistemological disagreement about the extent to which it is possible to distinguish "science" from "pseudoscience" in a reliable and objective way. The term itself has negative connotations, because it is used to indicate that subjects so labeled are inaccurately or deceptively portrayed as science. Accordingly, those labeled as practicing or advocating a "pseudoscience" normally reject this classification.

Pseudosciences have been characterised by the use of vague, exaggerated or untestable claims, over-reliance on confirmation rather than refutation, lack of openness to testing by other experts, and a lack of progress in theory development.


The standards for determining whether a body of knowledge, methodology, or practice is scientific can vary from field to field. There are, however, a number of basic principles that are widely agreed upon by scientists, such as reproducibility and intersubjective verifiability. Such principles aim to ensure that relevant evidence can be reproduced and/or measured given the same conditions, which allows further investigation to determine whether a hypothesis or theory related to given phenomena is both valid and reliable for use by others, including other scientists and researchers. It is expected that the scientific method will be applied throughout, and that bias will be controlled or eliminated, by double-blind studies, or statistically through fair sampling procedures. All gathered data, including experimental/environmental conditions, are expected to be documented for scrutiny and made available for peer review, thereby allowing further experiments or studies to be conducted to confirm or falsify results, as well as to determine other important factors such as statistical significance, confidence intervals, and margins of error.

In the mid-20th Century Karl Popper suggested the criterion of falsifiability to distinguish science from non-science. Statements such as "God created the universe" may be true or false, but no tests can be devised that could prove them false, so they are not scientific; they lie outside the scope of science. Popper subdivided non-science into philosophical, mathematical, mythological, religious and/or metaphysical formulations on the one hand, and pseudoscientific formulations on the other—though without providing clear criteria for the differences. He gave astrology and psychoanalysis as examples of pseudoscience, and Einstein's theory of relativity as an example of science. More recently, Paul Thagard (1978) proposed that pseudoscience is primarily distinguishable from science when it is less progressive than alternative theories over a long period of time, and the failure of proponents to acknowledge or address problems with the theory. Mario Bunge has suggested the categories of "belief fields" and "research fields" to help distinguish between science and pseudoscience.

Philosopher of science Paul Feyerabend has argued, from a sociology of knowledge perspective, that a distinction between science and non-science is neither possible nor desirable. Among the issues which can make the distinction difficult are that both the theories and methodologies of science evolve at differing rates in response to new data. In addition, the specific standards applicable to one field of science may not be those employed in other fields. Thagard also writes from a sociological perspective and states that "elucidation of how science differs from pseudoscience is the philosophical side of an attempt to overcome public neglect of genuine science."

Skeptics, most prominently represented by Richard Dawkins, Mario Bunge, Carl Sagan and James Randi, and the Brights movement consider all forms of pseudoscience to be harmful, whether or not they result in immediate harm to their adherents. These critics generally consider that the practice of pseudoscience may occur for a number of reasons, ranging from simple naïveté about the nature of science and the scientific method, to deliberate deception for financial or political gain. At the extreme, issues of personal health and safety may be very directly involved, for example in the case of physical or mental therapy or treatment, or in assessing safety risks. In such instances the potential for direct harm to patients, clients, the general public, or the environment may be an issue in assessing pseudoscience. (See also Junk science.)

The concept of pseudoscience as antagonistic to bona fide science appears to have emerged in the mid-19th century. Among the first recorded uses of the word "pseudo-science" was in 1844 in the Northern Journal of Medicine, I 387: "That opposite kind of innovation which pronounces what has been recognized as a branch of science, to have been a pseudo-science, composed merely of so-called facts, connected together by misapprehensions under the disguise of principles".

Identifying pseudoscience

A field, practice, or body of knowledge might reasonably be called pseudoscientific when (1) it is presented as consistent with the accepted norms of scientific research; but (2) it demonstrably fails to meet these norms, most importantly, in misuse of scientific method.

Subjects may be considered pseudoscientific for various reasons; Karl Popper considered astrology to be pseudoscientific simply because astrologers keep their claims so vague that they could never be refuted, whereas Paul R. Thagard considers astrology pseudoscientific because its practitioners make little effort to develop the theory, show no concern for attempts to critically evaluate the theory in relation to others, and are selective in considering evidence. More generally, Thagard stated that pseudoscience tends to focus on resemblances rather than cause-effect relations.

Science is also distinguishable from revelation, theology, or spirituality in that it claims to offer insight into the physical world obtained by "scientific" means. However, when scientific research produces conclusions which contradict a creationist interpretation of scripture, the strict creationist approach is either to reject the conclusions of the research, its underlying scientific theories, or its methodology. For this reason, both creation science and intelligent design have been labeled as pseudoscience by the mainstream scientific community. The most notable disputes concern the effects of evolution on the development of living organisms, the idea of common descent, the geologic history of the Earth, the formation of the solar system, and the origin of the universe. Systems of belief that derive from divine or inspired knowledge are not considered pseudoscience if they do not claim either to be scientific or to overturn well-established science.

Some statements and commonly held beliefs in popular science may not meet the criteria of science. "Pop" science may blur the divide between science and pseudoscience among the general public, and may also involve science fiction. Indeed, pop science is disseminated to, and can also easily emanate from, persons not accountable to scientific methodology and expert peer review.

If the claims of a given field can be experimentally tested and methodological standards are upheld, it is not "pseudoscience", however odd, astonishing, or counter-intuitive. If claims made are inconsistent with existing experimental results or established theory, but the methodology is sound, caution should be used; science consists of testing hypotheses which may turn out to be false. In such a case, the work may be better described as ideas that are not yet generally accepted.

The following have been proposed to be indicators of poor scientific reasoning.

Use of vague, exaggerated or untestable claims

  • Assertion of scientific claims that are vague rather than precise, and that lack specific measurements.
  • Failure to make use of operational definitions (i.e. publicly accessible definitions of the variables, terms, or objects of interest so that persons other than the definer can independently measure or test them). (See also: Reproducibility)
  • Failure to make reasonable use of the principle of parsimony, i.e. failing to seek an explanation that requires the fewest possible additional assumptions when multiple viable explanations are possible (see: Occam's Razor)
  • Use of obscurantist language, and misuse of apparently technical jargon in an effort to give claims the superficial trappings of science.
  • Lack of boundary conditions: Most well-supported scientific theories possess well-articulated limitations under which the predicted phenomena do and do not apply.
  • Lack of effective controls, such as placebo and double-blind, in experimental design. (see Scientific control)

Over-reliance on confirmation rather than refutation

  • An assertion should allow the logical possibility that it can be shown false by an observation or a physical experiment (see also: falsifiability)
  • Assertion of claims that a theory predicts something that it has not been shown to predict
  • Assertion that claims which have not been proven false must be true, and vice versa (see: Argument from ignorance)
  • Over-reliance on testimonial, anecdotal evidence or personal experience. This evidence may be useful for the context of discovery (i.e. hypothesis generation) but should not be used in the context of justification (e.g. Statistical hypothesis testing).
  • Pseudoscience often presents data that seems to support its claims while suppressing or refusing to consider data that conflict with its claims. This is an example of selection bias, a distortion of evidence or data that arises from the way that the data are collected. It is sometimes referred to as the selection effect.
  • Reversed burden of proof. In science, the burden of proof rests on those making a claim, not on the critic. "Pseudoscientific" arguments may neglect this principle and demand that skeptics demonstrate beyond a reasonable doubt that a claim (e.g. an assertion regarding the efficacy of a novel therapeutic technique) is false. It is essentially impossible to prove a universal negative, so this tactic incorrectly places the burden of proof on the skeptic rather than the claimant.
  • Appeals to holism as opposed to reductionism: Proponents of pseudoscientific claims, especially in organic medicine, alternative medicine, naturopathy and mental health, often resort to the “mantra of holism” to explain negative findings.

Lack of openness to testing by other experts

  • Evasion of peer review before publicizing results (called "science by press conference"). Some proponents of theories that contradict accepted scientific theories avoid subjecting their ideas to peer review, sometimes on the grounds that peer review is biased towards established paradigms, and sometimes on the grounds that assertions cannot be evaluated adequately using standard scientific methods. By remaining insulated from the peer review process, these proponents forgo the opportunity of corrective feedback from informed colleagues.
  • Some agencies, institutions, and publications that fund scientific research require authors to share data so that others can evaluate a paper independently. Failure to provide adequate information for other researchers to reproduce the claims contributes to a lack of openness.
  • Assertion of claims of secrecy or proprietary knowledge in response to requests for review of data or methodology.

Lack of progress

  • Failure to progress towards additional evidence of its claims. Terence Hines has identified astrology as a subject that has changed very little in the past two millennia. (see also: Scientific progress)
  • Lack of self correction: scientific research programmes make mistakes, but they tend to eliminate these errors over time. By contrast, theories may be accused of being pseudoscientific because they have remained unaltered despite contradictory evidence. The work Scientists Confront Velikovsky (1976) Cornell University, also delves into these features in some detail, as does the work of Thomas Kuhn, e.g. The Structure of Scientific Revolutions (1962) which also discusses some of the items on the list of characteristics of pseudoscience.

Personalization of issues

Use of misleading language

  • Creating scientific-sounding terms in order to add weight to claims and persuade non-experts to believe statements that may be false or meaningless. For example, a long-standing hoax refers to water as dihydrogen monoxide (DHMO) and describes it as the main constituent in most poisonous solutions to show how easily the general public can be misled.
  • Using established terms in idiosyncratic ways, thereby demonstrating unfamiliarity with mainstream work in the discipline.


The National Science Foundation stated that, in the USA, "pseudoscientific" beliefs became more widespread during the 1990s, peaked near 2001 and have declined slightly since; nevertheless, pseudoscientific beliefs remain common in the USA. As a result, according to the NSF report, there is a lack of knowledge of pseudoscientific issues in society and pseudoscientific practices are commonly followed. Bunge (1999) states that "A survey on public knowledge of science in the United States showed that in 1988 50% of American adults [rejected] evolution, and 88% [believed] astrology is a science'".

Commentators on pseudoscience perceive it in many fields; for example, Pseudomathematics is a term used for mathematics-like activity undertaken by either non-mathematicians or mathematicians themselves which does not conform to the rigorous standards usually applied to mathematical theorems.

Clinical psychology

Neurologists, clinical psychologists and other academics are concerned about the increasing amount of what they consider pseudoscience promoted in psychotherapy and popular psychology, and also about what they see as pseudoscientific therapies such as neuro-linguistic programming, EMDR, rebirthing, reparenting, and Primal Therapy being adopted by government and professional bodies and by the public. They state that scientifically unsupported therapies used by popular or folk psychology might harm vulnerable members of the public, undermine legitimate therapies, and tend to spread misconceptions about the nature of the mind and brain to society at large. Norcross et al. have approached the science/pseudoscience issue by conducting a survey of experts that seeks to specify which theory or therapy is considered to be definitely discredited, and they outline 14 fields that have been definitely discredited.

Psychological explanations

Pseudoscientific thinking has been explained in terms of psychology and social psychology. The human proclivity for seeking confirmation rather than refutation (confirmation bias), the tendency to hold comforting beliefs, and the tendency to overgeneralize have been proposed as reasons for the common adherence to pseudoscientific thinking. According to Beyerstein (1991) humans are prone to associations based on resemblances only, and often prone to misattribution in cause-effect thinking.

Some transitions from pseudoscience to science

There are examples of presently accepted scientific theories that were once criticised as being pseudoscientific. The transition is marked by increasing scientific scrutiny and specificity within the field and an increased level of evidence to support the theory. Continental drift theory was once considered pseudoscientific , but is now part of mainstream science especially since the paleomagnetic evidence was discovered that supported plate tectonics.

Atwood (2004) suggested that "Osteopathy has, for the most part, repudiated its pseudoscientific beginnings and joined the world of rational healthcare."

Criticisms of the concept of pseudoscience

Pseudoscience contrasted with protoscience and other "nonscience"

Protoscience is a term sometimes used to describe a hypothesis that has not yet been adequately tested by the scientific method, but which is otherwise consistent with existing science or which, where inconsistent, offers reasonable account of the inconsistency. It may also describe the transition from a body of practical knowledge into a scientific field. By contrast, "pseudoscience" is reserved to describe theories which are either untestable in practice or in principle, or which are maintained even when tests appear to have refuted them.

It is disputed (notably by Feyeraband, see above) whether meaningful boundaries can be drawn between pseudoscience, protoscience, and "real" science. Especially where there is a significant cultural or historical distance (as, for example, modern chemistry reflecting on alchemy), protosciences can be misinterpreted as pseudoscientific. After over a century of dialogue among philosophers of science and scientists in varied fields, and despite broad agreement on the basics of scientific method, the boundaries between science and non-science continue to be debated. This problem of demarcation can be problematic in cases where standard scientific ways (experiments, logic, etc.) of assessing a theory or a hypothesis cannot be applied for some reason.

On the utility of labels

Philosopher of science Larry Laudan has suggested that pseudoscience has no scientific meaning and mostly describes our emotions: "If we would stand up and be counted on the side of reason, we ought to drop terms like ‘pseudo-science’ and ‘unscientific’ from our vocabulary; they are just hollow phrases which do only emotive work for us". Richard McNally, Professor of Psychology at Harvard University, states: "The term 'pseudoscience' has become little more than an inflammatory buzzword for quickly dismissing one’s opponents in media sound-bites" and "When therapeutic entrepreneurs make claims on behalf of their interventions, we should not waste our time trying to determine whether their interventions qualify as pseudoscientific. Rather, we should ask them: How do you know that your intervention works? What is your evidence?

Examples of Pseudosciences

Further reading


External links

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