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.
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".
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.
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.
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."
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.
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?