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List of superseded scientific theories

This list includes well-known general theories in science and pre-scientific natural history and natural philosophy that have since been superseded by other scientific theories. Many discarded explanations were once supported by a scientific 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 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 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 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 Thus, it can be a mark of good science if a discipline has a growing list of superseded theories, and conversely, a lack of superseded theories can indicate problems in following the use of the scientific method.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 or female hysteria have been generated for political rather than empirical reasons and promoted by force.

Science

Discarded scientific theories

Biology

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 (O<sub>nasc</sub>) and nascent hydrogen (H<sub>nasc</sub>), and chlorine (Cl<sub>nasc</sub>) or bromine (Br<sub>nasc</sub>).
  • 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

Geography and climate

Geology

Psychology

Medicine

Obsolete branches of enquiry

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.

See also

Lists

Notes

References

External links