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 – 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'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,
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 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. •
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 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 and modern anthropology. •
Germ line theory, explained
immunoglobulin diversity by proposing that each
antibody was encoded in a separate germline gene.
Chemistry •
Energeticism – a theory that attempted to reinterpret all chemistry in terms of energy, rejecting the concept of atoms. •
Caloric theory – 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's name, a
unit of energy still used for
nutrition in some countries. •
Classical elements – 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's work on oxidation. • Point 2 of
Dalton's Atomic Theory was rendered obsolete by discovery of
isotopes, and point 3 by discovery of
subatomic particles 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 refers to the form of a
chemical element (or sometimes compound) in the instance of their liberation or formation. Often encountered are
atomic oxygen (Onasc) and
nascent hydrogen (Hnasc), and
chlorine (Clnasc) or bromine (Brnasc). •
Polywater, a hypothesized
polymer form of water, the properties of which actually arose from contaminants such as sweat.
Physics •
Corpuscularianism – theory that matter, gravity, light and magnetism are composed of tiny corpuscles •
Corpuscular theory of light •
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. •
Luminiferous aether – failed to be detected by the sufficiently sensitive
Michelson–Morley experiment, made obsolete by
Einstein's work. •
Caloric theory –
Lavoisier's successor to phlogiston, discredited by
Rumford's and
Joule's work. •
Vis viva –
Gottfried Leibniz's elementary and limited early formulation of the principle of conservation of energy. •
Horror vacui/plenum – concept that nature 'abhors' the existence of vacuum. •
Imponderable fluid – various fluids used to explain the nature of heat and electricity in terms of undetectable fluids •
Emitter theory – another now-obsolete theory of light propagation. • – the original theory by
Alessandro Volta misunderstood the active agent of a
voltaic cell to be a new type of
force acting on the
charges generated from contact of the
electrodes, what he called
contact tension.
Michael Faraday later correctly explained that the active agent for batteries was a chemical reaction, although Volta's science is correct as part of
contact electrification. •
Line of force – pre-existing theory to
field. •
Balance of nature – superseded by
catastrophe theory and
chaos theory. • 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'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 – superseded by Copernicus •
Copernican system – superseded by
Tychonic system •
Heliocentric universe – made obsolete by discovery of the structure of the
Milky Way and the
redshift 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. Superseded by
barycentric coordinates. • Aristotelian
Dynamics of the celestial spheres superseded by the
Elliptic orbit and
Kepler's laws of planetary motion •
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 model until evidence supporting the Big Bang and falsifying the steady state was found.
Geography and climate •
Ptolemy's estimate of the
size of the Earth •
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 •
Strait of Anian – a supposed strait connecting the Pacific and Atlantic Oceans, superseded by the Bering Strait (discovered 1728) •
Mountains of Kong and
Mountains of the Moon - mythical mountain ranges in Central Africa, based on the accounts of travelers •
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 climate change) • Climatic determinism • Topographic determinism • Moral geography • Cultural acclimatization •
Global cooling •
Drainage divides as always being made up by hills and mountains. • Ancient and medieval concepts surrounding the
antipodes, including the related theories of
antichthones and the alleged existence of a
torrid zone Geology •
Abiogenic petroleum origin – While some petroleum or natural gas is almost certainly abiogenic, the vast majority has origins as living organisms •
Catastrophism was largely replaced by
uniformitarianism and
neocatastrophism •
Cryptoexplosion craters, now discarded in favour of impact craters and ordinary volcanism. •
Flood geology replaced by modern geology and
stratigraphy •
Neptunism replaced by
plutonism and
volcanism •
Granitization, 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 • The following were superseded by
plate tectonics: •
Elevation crater theory •
Expanding Earth theory (superseded by
subduction) •
Contracting Earth •
Geosyncline theory •
Haarman's Oscillation theory • Various
lost landmasses including
Lemuria Psychology • Pure behaviorist explanations for
language acquisition in infancy, falsified by the study of cognitive adaptations for language. •
Psychomotor patterning, a
pseudoscientific approach to the treatment of
intellectual disabilities,
brain injury,
learning disabilities, and other
cognitive diseases.
Medicine • Theory of the
four bodily humours (see also
Four temperaments) •
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 – a theory of highly localised brain function popular in 19th century medicine. •
Homeopathy – 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, and is no longer considered a scientific theory •
Physiognomy, related to
phrenology, 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 •
Astrology, which led to the development of
astronomy •
Phrenology, a
pseudoscience •
Numerology, 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 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 was the first observational evidence that relativity was a more accurate model than
Newtonian gravity. •
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 for the
force of a
fluid 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. • 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 as a model of
human behavior •
Mendelian genetics,
classical genetics,
Boveri–Sutton chromosome theory – first genetic theories. Not invalidated as such, but subsumed into
molecular genetics. ==See also==