Pseudoscience is often characterized by the following: contradictory, exaggerated or unprovable claims; over-reliance on confirmation rather than rigorous attempts at refutation; lack of openness to evaluation by other experts in the field; and absence of systematic practices when rationally developing theories. The term pseudoscience is often considered pejorative because it suggests something is being inaccurately or even deceptively portrayed as science. Accordingly, those labeled as practicing or advocating pseudoscience often dispute the characterization.
Science is distinguishable from revelation, theology, or spirituality in that it offers insight into the physical world obtained by empirical research and testing. 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. Pseudoscientific beliefs are widespread, even among science teachers and newspaper editors.
The demarcation between science and pseudoscience has philosophical and scientific implications. Differentiating science from pseudoscience has practical implications in the case of health care, expert testimony, environmental policies, and science education. Distinguishing scientific facts and theories from pseudoscientific beliefs such as those found in astrology, alchemy, medical quackery, occult beliefs, and creation science combined with scientific concepts, is part of science education and scientific literacy.
Examples of pseudoscience concepts, proposed as scientific when they are not scientific, include acupuncture, alchemy, ancient astronauts, applied kinesiology, astrology, Ayurvedic medicine, biorhythms, cellular memory, cold fusion, craniometry, dowsing, Scientology founder L. Ron Hubbard's engram theory, enneagrams, esoteric healing, eugenics according to Edwin Black, extrasensory perception (ESP), facilitated communication, geocentrism, graphology, homeopathy, intelligent design, iridology, kundalini, Lysenkoism, metoposcopy, N-rays, naturopathy, orgone energy, paranormal plant perception, phrenology, physiognomy, polygraph, qi, New Age psychotherapies (e.g., rebirthing therapy), reflexology, remote viewing, neuro-linguistic programming (NLP), reiki, Rolfing, therapeutic touch, Vastu shastra, and the revised history of the solar system proposed by Immanuel Velikovsky.
Robert T. Carroll stated, in part, "Pseudoscientists claim to base their theories on empirical evidence, and they may even use some scientific methods, though often their understanding of a controlled experiment is inadequate. Many pseudoscientists relish being able to point out the consistency of their ideas with known facts or with predicted consequences, but they do not recognize that such consistency is not proof of anything. It is a necessary condition but not a sufficient condition that a good scientific theory be consistent with the facts."
In 2006, the U.S. National Science Foundation (NSF) issued an executive summary of a paper on science and engineering which briefly discussed the prevalence of pseudoscience in modern times. It said, "belief in pseudoscience is widespread" and, referencing a Gallup Poll, stated that belief in the 10 commonly believed examples of paranormal phenomena listed in the poll were "pseudoscientific beliefs". The items were "extrasensory perception (ESP), that houses can be haunted, ghosts, telepathy, clairvoyance, astrology, that people can communicate mentally with someone who has died, witches, reincarnation, and channelling". Such beliefs in pseudoscience reflect a lack of knowledge of how science works. The scientific community may aim to communicate information about science out of concern for the public's susceptibility to unproven claims.
The following are some of the indicators of the possible presence of pseudoscience.
- Use of vague, exaggerated or untestable claims
- Over-reliance on confirmation rather than refutation
- Lack of openness to testing by other experts
- Absence of progress
- Personalization of issues
- Use of misleading language