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Pathological science is the process by which "people are tricked into false results ... by subjective effects, wishful thinking or threshold interactions". The term was first used by Irving Langmuir, Nobel Prize-winning chemist, during a 1953 colloquium at the Knolls Research Laboratory. Langmuir said a pathological science is an area of research that simply will not "go away"—long after it was given up on as 'false' by the majority of scientists in the field. He called pathological science "the science of things that aren't so".
Bart Simon lists it among practices pretending to be science: "categories [.. such as ..] pseudoscience, amateur science, deviant or fraudulent science, bad science, junk science, and popular science [..] pathological science, cargo-cult science, and voodoo science ..". Examples of pathological science may include homeopathy, Martian canals, N-rays, polywater, water memory, perpetual motion, and cold fusion. The theories and conclusions behind all of these examples are currently rejected or disregarded by the majority of scientists.
Pathological science, as defined by Langmuir, is a psychological process in which a scientist, originally conforming to the scientific method, unconsciously veers from that method, and begins a pathological process of wishful data interpretation (see the Observer-expectancy effect, and cognitive bias). Some characteristics of pathological science are:
- The maximum effect that is observed is produced by a causative agent of barely detectable intensity, and the magnitude of the effect is substantially independent of the intensity of the cause.
- The effect is of a magnitude that remains close to the limit of detectability, or many measurements are necessary because of the very low statistical significance of the results.
- There are claims of great accuracy.
- Fantastic theories contrary to experience are suggested.
- Criticisms are met by ad hoc excuses.
- The ratio of supporters to critics rises and then falls gradually to oblivion.
Langmuir never intended the term to be rigorously defined; it was simply the title of his talk on some examples of "weird science". As with any attempt to define the scientific endeavor, examples and counterexamples can always be found.
Langmuir's examples 
In 1903, René-Prosper Blondlot was working on X-rays (as were many physicists of the era) and noticed a new visible radiation that could penetrate aluminium. He devised experiments in which a barely visible object was illuminated by these N-rays, and thus became "more visible". Blondlot claimed that N-rays were causing a small visual reaction, too small to be seen under normal illumination, but just visible when most "normal" light sources were removed and the target was just barely visible to begin with.
N-rays became the topic of some debate within the science community. After a time, physicist Robert W. Wood decided to visit Blondlot's lab, which had moved on to the physical characterization of N-rays. An experiment passed the rays from a 2 mm slit through an aluminum prism, from which he was measuring the index of refraction to a precision that required measurements accurate to within 0.01 mm. Wood asked how it was possible that he could measure something to 0.01 mm from a 2 mm source, a physical impossibility in the propagation of any kind of wave. Blondlot replied, "That's one of the fascinating things about the N-rays. They don't follow the ordinary laws of science that you ordinarily think of." Wood then asked to see the experiments being run as usual, which took place in a room required to be very dark so the target was barely visible. Blondlot repeated his most recent experiments and got the same results—despite the fact that Wood had reached over and covertly sabotaged the N-ray apparatus by removing the prism.
Other examples 
Langmuir offered additional examples of what he regarded as pathological science in his original speech:
- The Davis–Barnes effect (1929) (after Professor Bergen Davis from Columbia University)
- Mitogenetic rays (1923) (Alexander Gurwitsch and others)
- The Allison effect (1927) (after Fred Allison)
- Extrasensory perception (1934)
- Flying saucers and UFOs in the late 1940s and early 1950s.
Later examples 
A 1985 version of Langmuir's speech offered more examples, although at least one of these (polywater) occurred entirely after Langmuir's death in 1957:
- Water dowsing
- Martian canals (Observed in late 19th century and early 20th century, they turned out to be optical illusions.)
- Certain reported photomechanical and electromechanical effects[which?]
- Biological effects of magnetic fields (see magnetobiology and magnet therapy) except magnetoception
Newer examples 
Since Langmuir's original talk, a number of newer examples of what appear to be pathological science have appeared. Denis Rousseau, one of the main debunkers of polywater, gave an update of Langmuir in 1992, and he specifically cited as examples the cases of polywater, Fleischmann's cold fusion and Jacques Benveniste's "infinite dilution".
Polywater was a form of water which appeared to have a much higher boiling point and much lower freezing point than normal water. Many articles were published on the subject, and research on polywater was done around the world with mixed results. Eventually it was determined that many of the properties of polywater could be explained by biological contamination. When more rigorous cleaning of glassware and experimental controls were introduced, polywater could no longer be produced. It took several years for the concept of polywater to die in spite of the later negative results.
Cold fusion 
Since the announcement of Pons and Fleischmann in 1989, cold fusion has been considered to be an example of pathological science. Two panels convened by the US Department of Energy, one in 1989 and a second in 2004, did not recommend a dedicated federal program for cold fusion research.
Water memory 
Jacques Benveniste was a French immunologist who in 1988 published a paper in the prestigious scientific journal Nature describing the action of very high dilutions of anti-IgE antibody on the degranulation of human basophils, findings which seemed to support the concept of homeopathy. Biologists were puzzled by Benveniste's results, as only molecules of water, and no molecules of the original antibody, remained in these high dilutions. Benveniste concluded that the configuration of molecules in water was biologically active. Subsequent investigations have not supported Benveniste's findings, which are now cited as an example of pathological science.
See also 
- Paradigm shift
- Irving Langmuir, "Colloquium on Pathological Science", held at The Knolls Research Laboratory, December 18, 1953. A recording of the actual talk was made, but apparently lost, though a recorded transcript was produced by Langmuir a few months later. A transcript is available on the Web site of Kenneth Steiglitz, Professor of Computer Science, Princeton University. But see also: I. Langmuir, "Pathological Science", General Electric, (Distribution Unit, Bldg. 5, Room 345, Research and Development Center, P. O. Box 8, Schenectady, NY 12301), 68-C-035 (1968); I. Langmuir, "Pathological Science", (1989) Physics Today, Volume 42, Issue 10, October 1989, pp.36–48
- "Threshold interaction" refers to a phenomenon in statistical analysis where unforeseen relationships between input variables may cause unanticipated results. For example, see Dusseldorp, Voorjaarsbijeenkomst 2005
- Park, Robert (2000). Voodoo Science: The Road from Foolishness to Fraud. Oxford University Press. ISBN 0-19-860443-2.
- Bart Simon, "Undead Science: Science Studies and the Afterlife of Cold Fusion" (2002) ISBN 0-8135-3154-3. Simon refers to: Thomas F. Gieryn, "Cultural Boundaries of Science : Credibility on the Line" (1999) University Of Chicago Press, ISBN 0-226-29262-2
- Helge Kragh (1998). "Social constructivism, the Gospel of Science, and the Teaching of Physics". In Michael R. Matthews. Constructivism in science education: a philosophical examination (illustrated ed.). Springer. p. 134. ISBN 0-7923-5033-2, 9780792350330 Check
- transcript of speech
- For a review and bibliography, see Hollander and Claus, J. Opt. Soc. Am., 25, 270–286 (1935).
- F. Allison and E.S. Murphy, J. Am. Chem. Soc., 52, 3796 (1930). (b) F. Allison, Ind. Eng. Chem., 4, 9 (1932). (c) S. S. Cooper and T. R. Ball, J. Chem Ed., 13, 210 (1936), also pp. 278 and 326. (d) M. A. Jeppesen and R. M. Bell, Phys. Rev., 47, 546 (1935). (e) H. F. Mildrum and B. M. Schmidt, Air Force Aero Prop. Lab. AFAPL-TR-66-52 (May 1966).
- Eric Scerri (2009), "Finding francium", Nature Chemistry, In Your Element 670 (1), doi:10.1038/nchem.430, "Dozens of papers were published on this effect, including a number of studies arguing that it was spurious. These days the Allison effect is often featured in accounts of pathological science, alongside the claims for N-rays and cold fusion"
- Stanley Krippner, Harris L. Friedman (2010). Debating Psychic Experience: Human Potential Or Human Illusion? (illustrated ed.). ABC-CLIO. p. 151. ISBN 0-313-39261-7, 9780313392610 Check
|isbn=value (help). "Classic cases of pathological science, such as the alleged "discovery" of canals on Mars, N-rays, polywater, cold fusion, and so on are all testament to the fact that dozens of papers can appear in the scientific literature attesting to the reality of the phenomena, which turn out to be entirely illusory."
- Labinger JA, Weininger SJ (2005). "Controversy in chemistry: how do you prove a negative?—the cases of phlogiston and cold fusion". Angew Chem Int Ed Engl 44 (13): 1916–22. doi:10.1002/anie.200462084. PMID 15770617. "So there matters stand: no cold fusion researcher has been able to dispel the stigma of 'pathological science' by rigorously and reproducibly demonstrating effects sufficiently large to exclude the possibility of error (for example, by constructing a working power generator), nor does it seem possible to conclude unequivocally that all the apparently anomalous behavior can be attributed to error."
- D. L. Rousseau (January–February 1992). "Case Studies in Pathological Science: How the Loss of Objectivity Led to False Conclusions in Studies of Polywater, Infinite Dilution and Cold Fusion". American Scientist 80: 54–63.
- Carroll, Robert Todd, "pathological science". The Skeptic's Dictionary.
- Biberian, Jean-Paul (2007). "Condensed Matter Nuclear Science (Cold Fusion): An Update". International Journal of Nuclear Energy Science and Technology 3 (1): 31–43. doi:10.1504/IJNEST.2007.012439.
- Kirby, Geoff., "Forum: Now you see it...Now you don't – A pathological tendency among astronomers", New Scientist 24 February 1990
- Kowalski, Ludwik, "Pathological Science" (N-rays story). Montclair State University, Upper Montclair, N.J.
- Langmuir, I. and R. N. Hall., "Pathological Science". Colloquium at The Knolls Research Laboratory, December 18, 1953.
- Langmuir, Irving, and Robert N. Hall. "Pathological science". Physics Today 42 (10): 36–48. 1989.
- Turro, Nicholas J., "Toward a general theory of pathological science". 21stC: Issue 3.4 Strange Science.
- Wilson, James R., "Doctoral colloquium keynote address conduct, misconduct, and cargo cult science". Department of Industrial Engineering, North Carolina State University. Raleigh, North Carolina.
- Wynne, B., "G. G. Barkla and the J-Phenomenon: a Case Study of the Treatment of Deviance in Physics", Social Studies of Science, Vol.6, 1976, pp. 307–4 (abstract)