This list includes well-known general theories in science and pre-scientific natural philosophy and natural history that have since been superseded by other scientific theories. Many discarded explanations were once supported by a

scientific consensus Scientific consensus is the generally held judgment, position, and opinion of the majority or the supermajority of scientists in a particular field of study at any particular time. Consensus is achieved through scholarly communication at confe ...

, but replaced after more empirical information became available that identified flaws and prompted new theories which better explain the available data. Pre-modern explanations originated before the scientific method, with varying degrees of empirical support. Some scientific theories are discarded in their entirety, such as the replacement of the phlogiston theory by energy and thermodynamics. Some theories known to be incomplete or in some ways incorrect are still used. For example, Newtonian classical mechanics is accurate enough for practical calculations at everyday distances and velocities, and it is still taught in schools. The more complicated

relativistic mechanics In physics, relativistic mechanics refers to mechanics compatible with special relativity (SR) and general relativity (GR). It provides a non-quantum mechanical description of a system of particles, or of a fluid, in cases where the velocities of ...

must be used for long distances and velocities nearing the speed of light, and quantum mechanics for very small distances and objects. Some aspects of discarded theories are reused in modern explanations. For example,

miasma theory The miasma theory (also called the miasmatic theory) is an obsolete medical theory that held that diseases—such as cholera, chlamydia, or the Black Death—were caused by a ''miasma'' (, Ancient Greek for 'pollution'), a noxious form of "bad ...

proposed that all diseases were transmitted by "bad air". The modern germ theory of disease has found that diseases are caused by microorganisms, which can be transmitted by a variety of routes, including touching a contaminated object, blood, and contaminated water. Malaria was discovered to be a mosquito-borne disease, explaining why avoiding the "bad air" near swamps prevented it. Increasing ventilation of fresh air, one of the remedies proposed by miasma theory, does remain useful in some circumstances to expel germs spread by airborne transmission, such as SARS-CoV-2. Some theories originate in, or are perpetuated by, pseudoscience, which claims to be both scientific and factual, but fails to follow the scientific method. Scientific theories are testable and make falsifiable predictions. Thus, it can be a mark of good science if a discipline has a growing list of superseded theories, and conversely, a lack of superseded theories can indicate problems in following the use of the scientific method. '' Fringe science'' includes theories that are not currently supported by a consensus in the mainstream scientific community, either because they never had sufficient empirical support, because they were previously mainstream but later disproven, or because they are preliminary theories also known as '' protoscience'' which go on to become mainstream after empirical confirmation. Some theories, such as Lysenkoism,

race science Scientific racism, sometimes termed biological racism, is the pseudoscience, pseudoscientific belief that empirical evidence exists to support or justify racism (racial discrimination), racial inferiority, or racial superiority.. "Few tragedies ...

or female hysteria have been generated for political rather than empirical reasons and promoted by force.

Science

Discarded scientific theories

Biology

* Spontaneous generation – a principle regarding the spontaneous generation of complex life from inanimate matter, which held that this process was a commonplace and everyday occurrence, as distinguished from univocal generation, or reproduction from parent(s). Falsified by an experiment by Louis Pasteur: where apparently spontaneous generation of microorganisms occurred, it did not happen on repeating the process without access to unfiltered air; on then opening the apparatus to the atmosphere, bacterial growth started. * Transmutation of species, Inheritance of acquired characteristics, Lysenkoism – first theories of evolution. Not supported by experiment, and rendered obsolete by Darwinian evolution and Mendelian genetics, combined in the modern synthesis which finds that genes in the form of DNA are the primary way parental characteristics are passed to descendants. Discoveries in epigenetics have shown that in some very limited ways, the life experiences of organisms can affect the development of their children. *

Vitalism Vitalism is a belief that starts from the premise that "living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things." Wher ...

– the theory that living things are alive because of some "vital force" independent of matter, as opposed to because of some appropriate assembly of matter. It was gradually discredited by the rise of organic chemistry, biochemistry, and molecular biology, fields that failed to discover any "vital force."

Friedrich Wöhler Friedrich Wöhler () FRS(For) HonFRSE (31 July 180023 September 1882) was a German chemist known for his work in inorganic chemistry, being the first to isolate the chemical elements beryllium and yttrium in pure metallic form. He was the firs ...

's synthesis of urea from ammonium cyanate was only one step in a long road, not a great refutation. * Maternal impression – the theory that the mother's thoughts created birth defects. No experimental support (a notion rather than a theory), and rendered obsolete by genetic theory (see also

fetal origins of adult disease Thrifty phenotype refers to the correlation between low birth weight of neonates and the increased risk of developing metabolic syndromes later in life, including type 2 diabetes and cardiovascular diseases. Although early life undernutrition is th ...

, genomic imprinting). * Preformationism – the theory that all organisms have existed since the beginning of life, and that gametes contain a miniature but complete preformed individual, and in the case of humans, a homunculus. No support when

microscopy Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of micr ...

became available. Rendered obsolete by cytology, discovery of DNA, and atomic theory. * Recapitulation theory – the theory that "ontogeny recapitulates phylogeny". See

Baer's laws of embryology Von Baer's laws of embryology (or laws of development) are four rules proposed by Karl Ernst von Baer to explain the observed pattern of embryonic development in different species. Von Baer formulated the laws in the book ''Über Entwickelungsg ...

. * Telegony – the theory that an offspring can inherit characteristics from a previous mate of its mother's as well as its actual parents, often associated with racism. *

Out of Asia theory Out may refer to: Arts, entertainment, and media Films * ''Out'' (1957 film), a documentary short about the Hungarian Revolution of 1956 * ''Out'' (1982 film), an American film directed by Eli Hollander * ''Out'' (2002 film), a Japanese film ba ...

of human origin – The majority view is of a recent African origin of modern humans, although a multiregional origin of modern humans hypothesis has much support (which incorporates past evidence of Asian origins). * Scientific racism – the theory that humanity consists of physically discrete superior or inferior races. Rendered obsolete by

Human evolutionary genetics Human evolutionary genetics studies how one human genome differs from another human genome, the evolutionary past that gave rise to the human genome, and its current effects. Differences between genomes have anthropological, medical, historical and ...

and modern anthropology. * Mendelian genetics, classical genetics,

Boveri–Sutton chromosome theory The Boveri–Sutton chromosome theory (also known as the chromosome theory of inheritance or the Sutton–Boveri theory) is a fundamental unifying theory of genetics which identifies chromosomes as the carriers of genetic material.< ...

– first genetic theories. Not invalidated as such, but subsumed into molecular genetics. *

Germ line theory The germ-line theory was a proposed explanation for immunoglobulin diversity that proposed that each antibody was encoded in a separate germline gene. This does not occur in most species (including humans), but may occur in Elasmobranchs E ...

, explained

immunoglobulin diversity An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and Viral disease, viruses. The antibody recognizes a unique m ...

by proposing that each antibody was encoded in a separate germline gene.

Chemistry

Energeticism Energeticism, also called energism or energetics (german: Energetik), is a superseded theory in science that posits that energy is the ultimate element of physical reality. Energeticism was developed during the end of the 19th century by the chem ...

– a theory that attempted to reinterpret all chemistry in terms of energy, rejecting the concept of atoms. *

Caloric theory The caloric theory is an obsolete scientific theory that heat consists of a self-repellent fluid called caloric that flows from hotter bodies to colder bodies. Caloric was also thought of as a weightless gas that could pass in and out of pores i ...

– the theory that a self-repelling fluid called "caloric" was the substance of heat. Rendered obsolete by the mechanical theory of heat. Origin of the

calorie The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of on ...

's name, a unit of energy still used for nutrition in some countries. *

Classical element Classical elements typically refer to earth, water, air, fire, and (later) aether which were proposed to explain the nature and complexity of all matter in terms of simpler substances. Ancient cultures in Greece, Tibet, and India had simil ...

s – All matter was once thought composed of various combinations of classical elements (most famously air, earth, fire, and water). Antoine Lavoisier finally refuted this in his 1789 publication, '' Elements of Chemistry'', which contained the first modern list of chemical elements. * Electrochemical dualism – the theory that all molecules are salts composed of basic and acidic oxides * Phlogiston theory – The theory that combustible goods contain a substance called "phlogiston" that entered air during combustion. Replaced by

Lavoisier Antoine-Laurent de Lavoisier ( , ; ; 26 August 17438 May 1794),
CNRS (

Dalton's Atomic Theory John Dalton (; 5 or 6 September 1766 – 27 July 1844) was an English chemist, physicist and meteorologist. He is best known for introducing the atomic theory into chemistry, and for his research into colour blindness, which he had. Colour bl ...

was rendered obsolete by discovery of isotopes, and point 3 by discovery of

subatomic particle In physical sciences, a subatomic particle is a particle that composes an atom. According to the Standard Model of particle physics, a subatomic particle can be either a composite particle, which is composed of other particles (for example, a pr ...

s and nuclear reactions. * Radical theory – the theory that organic compounds exist as combinations of radicals that can be exchanged in chemical reactions just as chemical elements can be interchanged in inorganic compounds. * Vitalism – See section on Biology. *

Nascent state The nascent state (''Statu Nascenti'') is defined as a psychological process of destructuration-reorganization where the individual becomes capable of merging with other persons and creating a new collectivity with a very high degree of solidari ...

refers to the form of a chemical element (or sometimes compound) in the instance of their liberation or formation. Often encountered are

atomic oxygen There are several known allotropes of oxygen. The most familiar is molecular oxygen (O2), present at significant levels in Earth's atmosphere and also known as dioxygen or triplet oxygen. Another is the highly reactive ozone (O3). Others are: *A ...

(O_nasc) and

nascent hydrogen Nascent hydrogen is an outdated concept in organic chemistry that was once invoked to explain dissolving-metal reactions, such as the Clemmensen reduction and the Bouveault–Blanc reduction. Since organic compounds do not react with H2, a special ...

(H_nasc), and chlorine (Cl_nasc) or bromine (Br_nasc). * Polywater, a hypothesized polymer form of water, the properties of which actually arose from contaminants such as sweat

Physics

* Emission theory of vision – the belief that vision is caused by rays emanating from the eyes was superseded by the intro-mission approach and more complex theories of vision. * Aristotelian physics – superseded by Newtonian physics. * Ptolemy's law of refraction, replaced by

Snell's law Snell's law (also known as Snell–Descartes law and ibn-Sahl law and the law of refraction) is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through ...

. * Luminiferous aether – failed to be detected by the sufficiently sensitive Michelson–Morley experiment, made obsolete by

Einstein Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for developing the theory ...

's work. *

–

Lavoisier Antoine-Laurent de Lavoisier ( , ; ; 26 August 17438 May 1794),
CNRS (

Rumford Rumford may refer to: People * William Byron Rumford (1908–1986), California politician * Sir Benjamin Thompson, Count Rumford (1753–1814), American-British-German inventor, scientist, soldier, and official * Kennerley Rumford (1870–1957), ...

's and Joule's work. *

Contact tension Contact electrification is a phrase that describes a phenomenon whereby surfaces become electrically charged, via a number of possible mechanisms, when two or more objects come within close proximity of one another. When two objects are "touched" ...

– a theory on the source of electricity. * Vis viva – Gottfried Leibniz's elementary and limited early formulation of the principle of conservation of energy. * "Purely electrostatic" theories of the generation of voltage differences. *

Emitter theory Emission theory, also called emitter theory or ballistic theory of light, was a competing theory for the special theory of relativity, explaining the results of the Michelson–Morley experiment of 1887. Emission theories obey the principle of rel ...

– another now-obsolete theory of light propagation. * – the original theory by

Alessandro Volta Alessandro Giuseppe Antonio Anastasio Volta (, ; 18 February 1745 – 5 March 1827) was an Italian physicist, chemist and lay Catholic who was a pioneer of electricity and power who is credited as the inventor of the electric battery and the ...

misunderstood the active agent of a voltaic cell to be a new type of

force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a p ...

acting on the

charges Charge or charged may refer to: Arts, entertainment, and media Films * ''Charge, Zero Emissions/Maximum Speed'', a 2011 documentary Music * ''Charge'' (David Ford album) * ''Charge'' (Machel Montano album) * '' Charge!!'', an album by The Aqu ...

generated merely from contact of the electrodes. Michael Faraday later correctly explained the active agent was chemical reactions. *

Balance of nature The balance of nature, also known as ecological balance, is a theory that proposes that ecological systems are usually in a stable equilibrium or homeostasis, which is to say that a small change (the size of a particular population, for example) w ...

– superseded by

catastrophe theory In mathematics, catastrophe theory is a branch of bifurcation theory in the study of dynamical systems; it is also a particular special case of more general singularity theory in geometry. Bifurcation theory studies and classifies phenomena cha ...

and

chaos theory Chaos theory is an interdisciplinary area of scientific study and branch of mathematics focused on underlying patterns and deterministic laws of dynamical systems that are highly sensitive to initial conditions, and were once thought to have co ...

. * Progression of atomic theory ** Democritus, the originator of atomic theory, held that everything is composed of atoms that are indestructible. His claim that atoms are indestructible is not the reason it is superseded—as it was later scientists who identified the concept of atoms with particles, which later science showed are destructible. Democritus' theory is superseded because of his position that several kinds of atoms explain pure materials like water or iron, and characteristics that science now identifies with molecules rather than with indestructible primary particles. Democritus also held that between atoms, an empty space of a different nature than atoms allowed atoms to move. This view on space and matter persisted until Einstein described spacetime as being relative and connected to matter. **

John Dalton John Dalton (; 5 or 6 September 1766 – 27 July 1844) was an English chemist, physicist and meteorologist. He is best known for introducing the atomic theory into chemistry, and for his research into colour blindness, which he had. Colour b ...

's model of the atom, which held that atoms are indivisible and indestructible (superseded by nuclear physics) and that all atoms of a given element are identical in mass (superseded by discovery of atomic isotopes). ** Plum pudding model of the atom—assuming the protons and electrons were mixed together in a single mass ** Rutherford model of the atom with an impenetrable nucleus orbited by electrons ** Bohr model with quantized orbits ** Electron cloud model following the development of quantum mechanics in 1925 and the eventual atomic orbital models derived from the quantum mechanical solution to the hydrogen atom

Astronomy and cosmology

* Ptolemaic system – superseded by Nicolaus Copernicus' heliocentric model. *

Geocentric universe In astronomy, the geocentric model (also known as geocentrism, often exemplified specifically by the Ptolemaic system) is a superseded description of the Universe with Earth at the center. Under most geocentric models, the Sun, Moon, stars, an ...

– superseded by Copernicus * Copernican system - superseded by Tychonic system *

Heliocentric universe Heliocentrism (also known as the Heliocentric model) is the astronomical model in which the Earth and planets revolve around the Sun at the center of the universe. Historically, heliocentrism was opposed to Geocentric model, geocentrism, which p ...

– made obsolete by discovery of the structure of the Milky Way and the

redshift In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and simultaneous increase in f ...

of most galaxies. Heliocentrism only applies to the selected Solar System, and only approximately, since the Sun's center is not at the Solar System's

center of mass In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force may ...

. Superseded by barycentric coordinates. * Aristotelian Dynamics of the celestial spheres superseded by the Elliptic orbit and

Kepler's laws of planetary motion In astronomy, Kepler's laws of planetary motion, published by Johannes Kepler between 1609 and 1619, describe the orbits of planets around the Sun. The laws modified the heliocentric theory of Nicolaus Copernicus, replacing its circular orbits ...

* Tychonic system – superseded by Newton's laws of motion * Luminiferous aether theory * Static Universe theory * Steady state theory, a model developed by Hermann Bondi, Thomas Gold, and Fred Hoyle whereby the expanding universe was in a steady state, and had no beginning. It was a competitor of the

Big Bang The Big Bang event is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models of the Big Bang explain the evolution of the observable universe from the ...

model until evidence supporting the Big Bang and falsifying the steady state was found.

Geography and climate

* Buenaventura River * Flat Earth theory, generally known to be false among educated people in various ancient and medieval societies * Terra Australis, which technically is Antarctica, but the original idea was based on an unproven belief that land in the Northern hemisphere must have a Southern counterpart for balance. * Hollow Earth theory * The Open Polar Sea, an ice-free sea once supposed to surround the North Pole * Rain follows the plow – the theory that human settlement increases rainfall in arid regions (only true to the extent that crop fields evapotranspirate more than barren wilderness) * Island of California – the theory that California was not part of mainland North America but rather a large island * Inland sea of Australia * Pre-modern Environmental determinism (as explanations for moral behavior, as opposed to modern theories such as factor endowments, state formation, and theories of the social effects of global warming) **Climatic determinism **Topographic determinism **Moral geography **Cultural acclimatization * Global cooling *

Drainage divide A drainage divide, water divide, ridgeline, watershed, water parting or height of land is elevated terrain that separates neighboring drainage basins. On rugged land, the divide lies along topographical ridges, and may be in the form of a singl ...

s as always being made up by hills and mountains. * Ancient and medieval concepts surrounding the

antipodes In geography, the antipode () of any spot on Earth is the point on Earth's surface diametrically opposite to it. A pair of points ''antipodal'' () to each other are situated such that a straight line connecting the two would pass through Ear ...

, including the related theories of

antichthones Antichthones, in geography, are those peoples who inhabit the antipodes, regions on opposite sides of the Earth. The word is compounded of the Greek ''ὰντὶ'' ("opposed") and ''χθών'' ("earth"). Classical and Medieval Europe considere ...

and the alleged existence of a torrid zone

Geology

Abiogenic petroleum origin The abiogenic petroleum origin is a fringe science which proposes that most of earth's petroleum and natural gas deposits were formed inorganically. Mainstream theories about the formation of hydrocarbons on earth point to an origin from the decompo ...

– While some petroleum or natural gas is almost certainly abiogenic, the vast majority has origins as living organisms *

Catastrophism In geology, catastrophism theorises that the Earth has largely been shaped by sudden, short-lived, violent events, possibly worldwide in scope. This contrasts with uniformitarianism (sometimes called gradualism), according to which slow increment ...

was largely replaced by uniformitarianism and

neocatastrophism Neocatastrophism is the hypothesis that life-exterminating events such as gamma-ray bursts have acted as a galactic regulation mechanism in the Milky Way upon the emergence of complex life in its habitable zone.Cirković MM, Vukotić B. (2008). A ...

Cryptoexplosion In geology, a cryptoexplosion structure (or cryptovolcanic structure) is an explosion of unknown cause. The term is now largely obsolete. It was once commonly used to describe sites where there was geological evidence of a large-scale explosion wit ...

craters, now discarded in favour of impact craters and ordinary volcanism. *

Flood geology Flood geology (also creation geology or diluvial geology) is a pseudoscientific attempt to interpret and reconcile geological features of the Earth in accordance with a literal belief in the global flood described in Genesis 6–8. In the ea ...

replaced by modern geology and

stratigraphy Stratigraphy is a branch of geology concerned with the study of rock (geology), rock layers (Stratum, strata) and layering (stratification). It is primarily used in the study of sedimentary rock, sedimentary and layered volcanic rocks. Stratigrap ...

Neptunism Neptunism is a superseded scientific theory of geology proposed by Abraham Gottlob Werner (1749–1817) in the late 18th century, proposing that rocks formed from the crystallisation of minerals in the early Earth's oceans. The theory took its na ...

replaced by

plutonism Plutonism is the geologic theory that the igneous rocks forming the Earth originated from intrusive magmatic activity, with a continuing gradual process of weathering and erosion wearing away rocks, which were then deposited on the sea bed, re- ...

and volcanism *

Granitization Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergrou ...

, a discredited alternative to a magmatic origin of granites * Monoglaciation, the idea that the Earth had a single ice age, replaced by polyglaciation, the idea that the Earth has gone through several periods of widespread ice cover. * Oscillation theory of land-level rise and subsidence during

deglaciation Deglaciation is the transition from full glacial conditions during ice ages, to warm interglacials, characterized by global warming and sea level rise due to change in continental ice volume. Thus, it refers to the retreat of a glacier, an ice shee ...

* The following were superseded by plate tectonics: ** Elevation crater theory **

Expanding Earth theory The expanding Earth or growing Earth hypothesis argues that the position and relative movement of continents is at least partially due to the volume of Earth increasing. Conversely, geophysical global cooling was the hypothesis that various featu ...

(superseded by

subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

) **

Contracting Earth Before the concept of plate tectonics, global cooling was a geophysical theory by James Dwight Dana, also referred to as the contracting earth theory. It suggested that the Earth had been in a molten state, and features such as mountains formed as ...

Geosyncline theory A geosyncline (originally called a geosynclinal) is an obsolete geological concept to explain orogens, which was developed in the late 19th and early 20th centuries, before the theory of plate tectonics was envisaged. Şengör (1982), p. 11 A ge ...

** Haarman's Oscillation theory ** Various lost landmasses including

Lemuria Lemuria (), or Limuria, was a continent proposed in 1864 by zoologist Philip Sclater, theorized to have sunk beneath the Indian Ocean, later appropriated by occultists in supposed accounts of human origins. The theory was discredited with the di ...

Psychology

* Pure behaviorist explanations for

language acquisition Language acquisition is the process by which humans acquire the capacity to perceive and comprehend language (in other words, gain the ability to be aware of language and to understand it), as well as to produce and use words and sentences to ...

in infancy, falsified by the study of cognitive adaptations for language. *

Psychomotor patterning Psychomotor patterning, rarely referred to as the Doman-Delacato technique, is a pseudoscientific approach to the treatment of intellectual disabilities, brain injury, learning disabilities, and other cognitive diseases. The treatment is based on ...

, a

pseudoscientific Pseudoscience consists of statements, beliefs, or practices that claim to be both scientific and factual but are incompatible with the scientific method. Pseudoscience is often characterized by contradictory, exaggerated or unfalsifiable claim ...

approach to the treatment of

intellectual disabilities Intellectual disability (ID), also known as general learning disability in the United Kingdom and formerly mental retardation,Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010). is a generalized neurodevelopmental disorder characterized by signific ...

, brain injury, learning disabilities, and other

cognitive Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought, ...

diseases.

Medicine

* Theory of the four bodily humours (see also

Four temperaments The four temperament theory is a proto-psychological theory which suggests that there are four fundamental personality types: sanguine, choleric, melancholic, and phlegmatic. Most formulations include the possibility of mixtures among the types w ...

) ** Heroic medicine – a therapeutic method derived from the belief in bodily humour imbalances as the cause of ailments. * Miasma theory of disease – the theory that diseases are caused by "bad air". No experimental support, and rendered obsolete by the germ theory of disease. *

Phrenology Phrenology () is a pseudoscience which involves the measurement of bumps on the skull to predict mental traits.Wihe, J. V. (2002). "Science and Pseudoscience: A Primer in Critical Thinking." In ''Encyclopedia of Pseudoscience'', pp. 195–203. C ...

– a theory of highly localised brain function popular in 19th century medicine. *

Homeopathy Homeopathy or homoeopathy is a pseudoscientific system of alternative medicine. It was conceived in 1796 by the German physician Samuel Hahnemann. Its practitioners, called homeopaths, believe that a substance that causes symptoms of a dis ...

– a theory according to which a disease can be cured by infinitesimal doses of the substance that caused it * Eclectic medicine – transformed into

alternative medicine Alternative medicine is any practice that aims to achieve the healing effects of medicine despite lacking biological plausibility, testability, repeatability, or evidence from clinical trials. Complementary medicine (CM), complementary and alt ...

, and is no longer considered a scientific theory * Physiognomy, related to

phrenology Phrenology () is a pseudoscience which involves the measurement of bumps on the skull to predict mental traits.Wihe, J. V. (2002). "Science and Pseudoscience: A Primer in Critical Thinking." In ''Encyclopedia of Pseudoscience'', pp. 195–203. C ...

, held that inner character was strongly correlated with physical appearance * Tooth worm, an erroneous theory of the cause of dental caries, periodontitis, and toothaches

Obsolete branches of enquiry

* Alchemy, which led to the development of

chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...

* Astrology, which led to the development of astronomy *

, a pseudoscience *

Numerology Numerology (also known as arithmancy) is the belief in an occult, divine or mystical relationship between a number and one or more coinciding events. It is also the study of the numerical value, via an alphanumeric system, of the letters in ...

, a pseudoscience

Theories now considered incomplete

These theories that are no longer considered the most complete representation of reality but remain useful in particular domains or under certain conditions. For some theories, a more complete model is known, but for practical use, the coarser approximation provides good results with much less calculation. *

Newtonian mechanics Newton's laws of motion are three basic laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows: # A body remains at rest, or in motion ...

was extended by the theory of relativity and by quantum mechanics. Relativistic corrections to Newtonian mechanics are immeasurably small at velocities not approaching the speed of light, and quantum corrections are usually negligible at atomic or larger scales; Newtonian mechanics is totally satisfactory in engineering and physics under most circumstances. The anomalous

perihelion precession of Mercury Tests of general relativity serve to establish observational evidence for the theory of general relativity. The first three tests, proposed by Albert Einstein in 1915, concerned the "anomalous" precession of the perihelion of Mercury, the bendin ...

was the first observational evidence that relativity was a more accurate model than

Newtonian gravity Newton's law of universal gravitation is usually stated as that every particle attracts every other particle in the universe with a force that is proportional to the product of their masses and inversely proportional to the square of the distanc ...

. * Classical electrodynamics is a very close approximation to quantum electrodynamics except at very small scales and low field strengths. * The Bohr model of the atom was extended by the quantum mechanical model of the atom. * The formula known as

Newton's sine-square law of air resistance Isaac Newton's sine-squared law of air resistance is a formula that implies the force on a flat plate immersed in a moving fluid is proportional to the ''square'' of the sine of the angle of attack In fluid dynamics, angle of attack (AOA, α, ...

for the

of a

fluid In physics, a fluid is a liquid, gas, or other material that continuously deforms (''flows'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shear ...

on a body was not actually formulated by Newton but by others using a method of calculation used by Newton; it has been found incorrect and not useful except for high-speed

hypersonic flow In aerodynamics, a hypersonic speed is one that exceeds 5 times the speed of sound, often stated as starting at speeds of speed of sound, Mach 5 and above. The precise Mach number at which a craft can be said to be flying at hypersonic speed va ...

.Aerodynamics: Selected Topics in the Light of Their Historical Development, book by Theodore Von Karman, 1954, Dover Publications, p10 and following pages
Detailed discussion of Newton's sine-square law, invalidity in the general case and applicability at high supersonic speeds. * The once-popular cycle of erosion is now considered one of many possibilities for landscape evolution. * The theory of continental drift was incorporated into and improved upon by plate tectonics. *

Rational choice theory Rational choice theory refers to a set of guidelines that help understand economic and social behaviour. The theory originated in the eighteenth century and can be traced back to political economist and philosopher, Adam Smith. The theory postula ...

as a model of human behavior.

Notes

References

External links

* {{Mathematical logic Obsolete scientific theories Mathematical proofs Theorems