Pseudoscience is any body of knowledge, methodology, belief, or practice that claims to be scientific or is made to appear scientific, but does not adhere to the basic requirements of the scientific method.
The term pseudoscience is based on the Greek root pseudo- (false or pretending) and science (derived from Latin scientia, meaning knowledge). The first recorded use was in 1843 by French physiologist François Magendie considered a pioneer in experimental physiology.
The term 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.
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, eugenics, 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 whether it is possible to distinguish "science" from "pseudoscience" in a reliable and objective way.
Pseudosciences may be 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.