This list includes well-known general theories in science and pre-scientificnatural history andnatural philosophy that have since been superseded by otherscientific theories. Many discarded explanations were once supported by ascientific consensus, 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 thescientific method, with varying degrees of empirical support.
Some scientific theories are discarded in their entirety, such as the replacement of thephlogiston theory by energy andthermodynamics. Some theories known to be incomplete or in some ways incorrect are still used. For example, Newtonianclassical mechanics is accurate enough for practical calculations at everyday distances and velocities, and it is still taught in schools. The more complicatedrelativistic mechanics must be used for long distances and velocities nearing thespeed of light, andquantum mechanics for very small distances and objects.
Some aspects of discarded theories are reused in modern explanations. For example,miasma theory proposed that all diseases were transmitted by "bad air". The moderngerm theory of disease has found that diseases are caused by microorganisms, which can be transmitted by a variety of routes, includingtouching a contaminated object,blood, andcontaminated water.Malaria was discovered to be amosquito-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 byairborne transmission, such asSARS-CoV-2.[1]
Some theories originate in, or are perpetuated by,pseudoscience, which claims to be both scientific and factual, but fails to follow thescientific method. Scientific theories aretestable and makefalsifiablepredictions.[2] Thus, it can be a mark of good science if a discipline has a growing list of superseded theories, and conversely, a lack of superseded theories can indicate problems in following the use of the scientific method.Fringe science includes theories that are not currently supported by a consensus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 mainstreamscientific 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 asprotoscience which go on to become mainstream after empirical confirmation. Some theories, such asLysenkoism,race science orfemale hysteria have been generated for political rather than empirical reasons and promoted by force.
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 anexperiment 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.[3]
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 oforganic chemistry,biochemistry, andmolecular biology, fields that failed to discover any "vital force."Friedrich Wöhler's synthesis ofurea fromammonium cyanate was only one step in a long road, not a great refutation.[5][6]
Preformationism – the theory that all organisms have existed since the beginning of life, and thatgametes contain a miniature but complete preformed individual, and in the case of humans, ahomunculus. No support whenmicroscopy became available. Rendered obsolete bycytology, discovery ofDNA, andatomic theory.
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.
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 byLavoisier's work on oxidation.
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.
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).[13]
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
Heliocentric universe – made obsolete by discovery of the structure of theMilky Way and theredshift 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'scenter of mass. Superseded bybarycentric coordinates.
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.
TheOpen 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
Granitization, a discredited alternative to a magmatic origin of granites
Monoglaciation, the idea that the Earth had a singleice age, replaced bypolyglaciation, the idea that the Earth has gone through several periods of widespread ice cover.[17]
Oscillation theory of land-level rise and subsidence duringdeglaciation
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 thetheory of relativity and byquantum mechanics. Relativistic corrections to Newtonian mechanics are immeasurably small at velocities not approaching thespeed of light,[20] and quantum corrections are usually negligible at atomic or larger scales;[21] Newtonian mechanics is totally satisfactory in engineering and physics under most circumstances. The anomalousperihelion precession of Mercury was the first observational evidence that relativity was a more accurate model thanNewtonian gravity.
^Antipodes and antichthones do literally exist as opposite points on the Earth and people who live on and around them, but do not have any of the unique properties ascribed to them by ancient or medieval authors.
^Popper, Karl (1963),Conjectures and Refutations, Routledge and Kegan Paul, London, UK. Reprinted inTheodore Schick (ed., 2000),Readings in the Philosophy of Science, Mayfield Publishing Company, Mountain View, Calif.
^Crain, Stephen and Diane C. Lillo-Martin (1999).An Introduction to Linguistic Theory and Language Acquisition. Oxford: Blackwell.{{cite book}}: CS1 maint: publisher location (link)
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