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115-428: In modern science, the term "theory" refers to scientific theories , a well-confirmed type of explanation of nature , made in a way consistent with the scientific method , and fulfilling the criteria required by modern science . Such theories are described in such a way that scientific tests should be able to provide empirical support for it, or empirical contradiction (" falsify ") of it. Scientific theories are

230-406: A common ancestor . Acceptance of a theory does not require that all of its major predictions be tested, if it is already supported by sufficiently strong evidence. For example, certain tests may be unfeasible or technically difficult. As a result, theories may make predictions that have not yet been confirmed or proven incorrect; in this case, the predicted results may be described informally with

345-720: A hypothesis . If a new theory better explains and predicts a phenomenon than an old theory (i.e., it has more explanatory power ), we are justified in believing that the newer theory describes reality more correctly. This is called an intertheoretic reduction because the terms of the old theory can be reduced to the terms of the new one. For instance, our historical understanding about sound , light and heat have been reduced to wave compressions and rarefactions , electromagnetic waves , and molecular kinetic energy , respectively. These terms, which are identified with each other, are called intertheoretic identities. When an old and new theory are parallel in this way, we can conclude that

460-515: A knowledge transfer where there is a task of translating research knowledge to be application in practice, and ensuring that practitioners are made aware of it. Academics have been criticized for not attempting to transfer the knowledge they produce to practitioners. Another framing supposes that theory and knowledge seek to understand different problems and model the world in different words (using different ontologies and epistemologies ). Another framing says that research does not produce theory that

575-496: A scientific fact or scientific law in that a theory seeks to explain "why" or "how", whereas a fact is a simple, basic observation and a law is an empirical description of a relationship between facts and/or other laws. For example, Newton's Law of Gravity is a mathematical equation that can be used to predict the attraction between bodies, but it is not a theory to explain how gravity works. Stephen Jay Gould wrote that "...facts and theories are different things, not rungs in

690-443: A "root" metaphor that constrains how scientists theorize and model a phenomenon and thus arrive at testable hypotheses. Engineering practice makes a distinction between "mathematical models" and "physical models"; the cost of fabricating a physical model can be minimized by first creating a mathematical model using a computer software package, such as a computer aided design tool. The component parts are each themselves modelled, and

805-470: A bed have no tendency to become a bed.) In terms of Aristotle's theory of four causes , the word natural is applied both to the innate potential of matter cause and the forms which the matter tends to become naturally. According to Leo Strauss , the beginning of Western philosophy involved the "discovery or invention of nature" and the "pre-philosophical equivalent of nature" was supplied by "such notions as 'custom' or 'ways'". In ancient Greek philosophy on

920-432: A direct result. The phrase " the received view of theories " is used to describe this approach. Terms commonly associated with it are " linguistic " (because theories are components of a language) and " syntactic " (because a language has rules about how symbols can be strung together). Problems in defining this kind of language precisely, e.g., are objects seen in microscopes observed or are they theoretical objects, led to

1035-534: A distance —Einstein presumed a gravitational field. In 1907, Einstein's equivalence principle implied that a free fall within a uniform gravitational field is equivalent to inertial motion. By extending special relativity's effects into three dimensions, general relativity extended length contraction into space contraction , conceiving of 4D space-time as the gravitational field that alters geometrically and sets all local objects' pathways. Even massless energy exerts gravitational motion on local objects by "curving"

1150-445: A doctrine about how it is possible that people know things: "If nothing exists apart from individual things, nothing will be intelligible; everything will be sensible, and there will be no knowledge of anything—unless it be maintained that sense-perception is knowledge". Those philosophers who disagree with this reasoning therefore also see knowledge differently from Aristotle. Aristotle then, described nature or natures as follows, in

1265-419: A first step toward being tested or applied in a concrete situation; theorems are said to be true in the sense that the conclusions of a theorem are logical consequences of the axioms. Theories are abstract and conceptual, and are supported or challenged by observations in the world. They are ' rigorously tentative', meaning that they are proposed as true and expected to satisfy careful examination to account for

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1380-413: A foundation to gain further scientific knowledge, as well as to accomplish goals such as inventing technology or curing diseases. The United States National Academy of Sciences defines scientific theories as follows: The formal scientific definition of "theory" is quite different from the everyday meaning of the word. It refers to a comprehensive explanation of some aspect of nature that is supported by

1495-435: A given subject matter. There are theories in many and varied fields of study, including the arts and sciences. A formal theory is syntactic in nature and is only meaningful when given a semantic component by applying it to some content (e.g., facts and relationships of the actual historical world as it is unfolding). Theories in various fields of study are often expressed in natural language , but can be constructed in such

1610-426: A graphical model that represents the territory of a city or country. In this approach, theories are a specific category of models that fulfill the necessary criteria (see above ). One can use language to describe a model; however, the theory is the model (or a collection of similar models), and not the description of the model. A model of the solar system, for example, might consist of abstract objects that represent

1725-465: A hierarchy of increasing certainty. Facts are the world's data. Theories are structures of ideas that explain and interpret facts." The meaning of the term scientific theory (often contracted to theory for brevity) as used in the disciplines of science is significantly different from the common vernacular usage of theory . In everyday speech, theory can imply an explanation that represents an unsubstantiated and speculative guess , whereas in

1840-416: A human-like consciousness involved in the causation of all things, even things which are not man-made. Nature itself is attributed with having aims. The artificial, like the conventional therefore, is within this branch of Western thought, traditionally contrasted with the natural. Technology was contrasted with science , as mentioned above. And another essential aspect to this understanding of causation

1955-474: A more accurate theory is then required. Some theories are so well-established that they are unlikely ever to be fundamentally changed (for example, scientific theories such as evolution , heliocentric theory , cell theory , theory of plate tectonics , germ theory of disease , etc.). In certain cases, a scientific theory or scientific law that fails to fit all data can still be useful (due to its simplicity) as an approximation under specific conditions. An example

2070-416: A particular social institution. Most of the following are scientific theories. Some are not, but rather encompass a body of knowledge or art, such as Music theory and Visual Arts Theories. Scientific theory A scientific theory is an explanation of an aspect of the natural world and universe that can be (or a fortiori , that has been) repeatedly tested and corroborated in accordance with

2185-471: A philosophical term derived from the verb for birth , which was used as a translation for the earlier ( pre-Socratic ) Greek term phusis , derived from the verb for natural growth. Already in classical times, philosophical use of these words combined two related meanings which have in common that they refer to the way in which things happen by themselves, "naturally", without "interference" from human deliberation, divine intervention, or anything outside what

2300-447: A recursively enumerable set) in which the concept of natural numbers can be expressed, can include all true statements about them. As a result, some domains of knowledge cannot be formalized, accurately and completely, as mathematical theories. (Here, formalizing accurately and completely means that all true propositions—and only true propositions—are derivable within the mathematical system.) This limitation, however, in no way precludes

2415-410: A scale model of a house or of a solar system is clearly not an actual house or an actual solar system; the aspects of an actual house or an actual solar system represented in a scale model are, only in certain limited ways, representative of the actual entity. A scale model of a house is not a house; but to someone who wants to learn about houses, analogous to a scientist who wants to understand reality,

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2530-415: A scientific context it most often refers to an explanation that has already been tested and is widely accepted as valid. The strength of a scientific theory is related to the diversity of phenomena it can explain and its simplicity. As additional scientific evidence is gathered, a scientific theory may be modified and ultimately rejected if it cannot be made to fit the new findings; in such circumstances,

2645-436: A single textbook. In mathematical logic , a theory has a related but different sense: it is the collection of the theorems that can be deduced from a given set of axioms , given a given set of inference rules . A theory can be either descriptive as in science, or prescriptive ( normative ) as in philosophy. The latter are those whose subject matter consists not of empirical data, but rather of ideas . At least some of

2760-552: A small set of basic postulates (usually symmetries, like equality of locations in space or in time, or identity of electrons, etc.)—which is capable of producing experimental predictions for a given category of physical systems. One good example is classical electromagnetism , which encompasses results derived from gauge symmetry (sometimes called gauge invariance) in a form of a few equations called Maxwell's equations . The specific mathematical aspects of classical electromagnetic theory are termed "laws of electromagnetism", reflecting

2875-461: A source of motion; for the matter is called "nature" because it is capable of receiving the nature, and the processes of generation and growth are called "nature" because they are motions derived from it. And nature in this sense is the source of motion in natural objects, which is somehow inherent in them, either potentially or actually. It has been argued, as will be explained below, that this type of theory represented an oversimplifying diversion from

2990-420: A sufficiently detailed scale model may suffice. Several commentators have stated that the distinguishing characteristic of theories is that they are explanatory as well as descriptive, while models are only descriptive (although still predictive in a more limited sense). Philosopher Stephen Pepper also distinguished between theories and models, and said in 1948 that general models and theories are predicated on

3105-480: A technical term in philosophy in Ancient Greek . As an everyday word, theoria , θεωρία , meant "looking at, viewing, beholding", but in more technical contexts it came to refer to contemplative or speculative understandings of natural things , such as those of natural philosophers , as opposed to more practical ways of knowing things, like that of skilled orators or artisans. English-speakers have used

3220-542: A theory by finding even a single observation that disagrees with the predictions of the theory". Several philosophers and historians of science have, however, argued that Popper's definition of theory as a set of falsifiable statements is wrong because, as Philip Kitcher has pointed out, if one took a strictly Popperian view of "theory", observations of Uranus when first discovered in 1781 would have "falsified" Newton's celestial mechanics. Rather, people suggested that another planet influenced Uranus' orbit—and this prediction

3335-417: A theory does not require modification despite repeated tests, this implies that the theory is very accurate. This also means that accepted theories continue to accumulate evidence over time, and the length of time that a theory (or any of its principles) remains accepted often indicates the strength of its supporting evidence. In some cases, two or more theories may be replaced by a single theory that explains

3450-411: A theory is proposed and accepted, the previous theory will be retained. This is because it is still the best available explanation for many other phenomena, as verified by its predictive power in other contexts. For example, it has been known since 1859 that the observed perihelion precession of Mercury violates Newtonian mechanics, but the theory remained the best explanation available until relativity

3565-441: A theory must include statements that have observational consequences. But, like the observation of irregularities in the orbit of Uranus, falsification is only one possible consequence of observation. The production of new hypotheses is another possible and equally important result. The concept of a scientific theory has also been described using analogies and metaphors. For example, the logical empiricist Carl Gustav Hempel likened

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3680-403: A theory of heat as energy replaced it. Also, the theory that phlogiston is a substance released from burning and rusting material was eliminated with the new understanding of the reactivity of oxygen. Theories are distinct from theorems . A theorem is derived deductively from axioms (basic assumptions) according to a formal system of rules, sometimes as an end in itself and sometimes as

3795-401: A theory's content is based on some formal system of logic and on basic axioms . In a deductive theory, any sentence which is a logical consequence of one or more of the axioms is also a sentence of that theory. This is called the received view of theories . In the semantic view of theories , which has largely replaced the received view, theories are viewed as scientific models . A model

3910-548: A vast body of evidence. Many scientific theories are so well established that no new evidence is likely to alter them substantially. For example, no new evidence will demonstrate that the Earth does not orbit around the sun (heliocentric theory), or that living things are not made of cells (cell theory), that matter is not composed of atoms, or that the surface of the Earth is not divided into solid plates that have moved over geological timescales (the theory of plate tectonics) ... One of

4025-498: A way quite different from modern science: " Nature " means: (a) in one sense, the genesis of growing things — as would be suggested by pronouncing the υ of φύσις long—and (b) in another, that immanent thing from which a growing thing first begins to grow. (c) The source from which the primary motion in every natural object is induced in that object as such. All things are said to grow which gain increase through something else by contact and organic unity (or adhesion, as in

4140-419: A way that their general form is identical to a theory as it is expressed in the formal language of mathematical logic . Theories may be expressed mathematically, symbolically, or in common language, but are generally expected to follow principles of rational thought or logic . Theory is constructed of a set of sentences that are thought to be true statements about the subject under consideration. However,

4255-534: Is Aristotle 's principal work on nature. In Physics II .1, Aristotle defines a nature as "a source or cause of being moved and of being at rest in that to which it belongs primarily". In other words, a nature is the principle within a natural raw material that is the source of tendencies to change or rest in a particular way unless stopped. For example, a rock would fall unless stopped. Natural things stand in contrast to artifacts, which are formed by human artifice, not because of an innate tendency. (The raw materials of

4370-838: Is Newton's laws of motion , which are a highly accurate approximation to special relativity at velocities that are small relative to the speed of light . Scientific theories are testable and make verifiable predictions . They describe the causes of a particular natural phenomenon and are used to explain and predict aspects of the physical universe or specific areas of inquiry (for example, electricity, chemistry, and astronomy). As with other forms of scientific knowledge, scientific theories are both deductive and inductive , aiming for predictive and explanatory power . Scientists use theories to further scientific knowledge, as well as to facilitate advances in technology or medicine . Scientific hypotheses can never be "proven" because scientists are not able to fully confirm that their hypothesis

4485-416: Is "by nature" is contrasted to what is "by convention". The concept of nature taken this far remains a strong tradition in modern Western thinking . Science , according to Strauss' commentary of Western history is the contemplation of nature, while technology was or is an attempt to imitate it. Going further, the philosophical concept of nature or natures as a special type of causation - for example that

4600-617: Is a conjunction of ad- ("to, towards, at") and sumere (to take). The root survives, with shifted meanings, in the Italian assumere and Spanish sumir . The first sense of "assume" in the OED is "to take unto (oneself), receive, accept, adopt". The term was originally employed in religious contexts as in "to receive up into heaven", especially "the reception of the Virgin Mary into heaven, with body preserved from corruption", (1297 CE) but it

4715-409: Is a good theory if it satisfies two requirements: It must accurately describe a large class of observations on the basis of a model that contains only a few arbitrary elements, and it must make definite predictions about the results of future observations." He also discusses the "unprovable but falsifiable" nature of theories, which is a necessary consequence of inductive logic, and that "you can disprove

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4830-421: Is a logical framework intended to represent reality (a "model of reality"), similar to the way that a map is a graphical model that represents the territory of a city or country. In this approach, theories are a specific category of models that fulfill the necessary criteria. (See Theories as models for further discussion.) In physics the term theory is generally used for a mathematical framework—derived from

4945-526: Is a statement that can be derived from those axioms by application of these rules of inference. Theories used in applications are abstractions of observed phenomena and the resulting theorems provide solutions to real-world problems. Obvious examples include arithmetic (abstracting concepts of number), geometry (concepts of space), and probability (concepts of randomness and likelihood). Gödel's incompleteness theorem shows that no consistent, recursively enumerable theory (that is, one whose theorems form

5060-665: Is a statement that is accepted without evidence. For example, assumptions can be used as premises in a logical argument. Isaac Asimov described assumptions as follows: ...it is incorrect to speak of an assumption as either true or false, since there is no way of proving it to be either (If there were, it would no longer be an assumption). It is better to consider assumptions as either useful or useless, depending on whether deductions made from them corresponded to reality...Since we must start somewhere, we must have assumptions, but at least let us have as few assumptions as possible. Certain assumptions are necessary for all empirical claims (e.g.

5175-475: Is achieved. Since each new version of a theory (or a completely new theory) must have more predictive and explanatory power than the last, scientific knowledge consistently becomes more accurate over time. If modifications to the theory or other explanations seem to be insufficient to account for the new results, then a new theory may be required. Since scientific knowledge is usually durable, this occurs much less commonly than modification. Furthermore, until such

5290-416: Is already present, we say that they have not their nature yet unless they have their form and shape. That which comprises both of these exists by nature; e.g. animals and their parts. And nature is both the primary matter (and this in two senses: either primary in relation to the thing, or primary in general; e.g., in bronze articles the primary matter in relation to those articles is bronze, but in general it

5405-587: Is also resolved by either further evidence or unification. For example, physical theories in the 19th century implied that the Sun could not have been burning long enough to allow certain geological changes as well as the evolution of life. This was resolved by the discovery of nuclear fusion , the main energy source of the Sun. Contradictions can also be explained as the result of theories approximating more fundamental (non-contradictory) phenomena. For example, atomic theory

5520-559: Is also tested, and if it fulfills the necessary criteria (see above), then the explanation becomes a theory. This can take many years, as it can be difficult or complicated to gather sufficient evidence. Once all of the criteria have been met, it will be widely accepted by scientists (see scientific consensus ) as the best available explanation of at least some phenomena. It will have made predictions of phenomena that previous theories could not explain or could not predict accurately, and it will have many repeated bouts of testing. The strength of

5635-593: Is an approximation of quantum mechanics . Current theories describe three separate fundamental phenomena of which all other theories are approximations; the potential unification of these is sometimes called the Theory of Everything . In 1905, Albert Einstein published the principle of special relativity , which soon became a theory. Special relativity predicted the alignment of the Newtonian principle of Galilean invariance , also termed Galilean relativity , with

5750-434: Is both a theory and a fact . The logical positivists thought of scientific theories as statements in a formal language . First-order logic is an example of a formal language. The logical positivists envisaged a similar scientific language. In addition to scientific theories, the language also included observation sentences ("the sun rises in the east"), definitions, and mathematical statements. The phenomena explained by

5865-434: Is considered normal for the natural things being considered. Understandings of nature depend on the subject and age of the work where they appear. For example, Aristotle 's explanation of natural properties differs from what is meant by natural properties in modern philosophical and scientific works, which can also differ from other scientific and conventional usage. The Physics (from ta phusika "the natural [things]")

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5980-441: Is perhaps water—that is if all things which can be melted are water) and the form or essence , i.e. the end of the process, of generation. Indeed from this sense of "nature," by an extension of meaning, every essence in general is called "nature," because the nature of anything is a kind of essence. From what has been said, then, the primary and proper sense of "nature" is the essence of those things which contain in themselves as such

6095-481: Is produced; e.g., bronze is called the "nature" of a statue and of bronze articles, and wood that of wooden ones, and similarly in all other cases. For each article consists of these "natures," the primary material persisting. It is in this sense that men call the elements of natural objects the "nature," some calling it fire, others earth or air or water, others something else similar, others some of these, and others all of them. Again in another sense "nature" means (e)

6210-484: Is relevant to practice. In the context of management, Van de Van and Johnson propose a form of engaged scholarship where scholars examine problems that occur in practice, in an interdisciplinary fashion, producing results that create both new practical results as well as new theoretical models, but targeting theoretical results shared in an academic fashion. They use a metaphor of "arbitrage" of ideas between disciplines, distinguishing it from collaboration. In science,

6325-510: Is supported by a vast body of evidence. Many scientific theories are so well established that no new evidence is likely to alter them substantially. For example, no new evidence will demonstrate that the Earth does not orbit around the Sun (heliocentric theory), or that living things are not made of cells (cell theory), that matter is not composed of atoms, or that the surface of the Earth is not divided into solid plates that have moved over geological timescales (the theory of plate tectonics)...One of

6440-664: Is that scientific theories are rudimentary ideas that will eventually graduate into scientific laws when enough data and evidence have been accumulated. A theory does not change into a scientific law with the accumulation of new or better evidence. A theory will always remain a theory; a law will always remain a law. Both theories and laws could potentially be falsified by countervailing evidence. Theories and laws are also distinct from hypotheses . Unlike hypotheses, theories and laws may be simply referred to as scientific fact . However, in science, theories are different from facts even when they are well supported. For example, evolution

6555-477: Is true. Instead, scientists say that the study "supports" or is consistent with their hypothesis. Albert Einstein described two different types of scientific theories: "Constructive theories" and "principle theories". Constructive theories are constructive models for phenomena: for example, kinetic theory . Principle theories are empirical generalisations, one such example being Newton's laws of motion . For any theory to be accepted within most academia there

6670-707: Is under the theory. Sometimes two theories have exactly the same explanatory power because they make the same predictions. A pair of such theories is called indistinguishable or observationally equivalent , and the choice between them reduces to convenience or philosophical preference. The form of theories is studied formally in mathematical logic, especially in model theory . When theories are studied in mathematics, they are usually expressed in some formal language and their statements are closed under application of certain procedures called rules of inference . A special case of this, an axiomatic theory, consists of axioms (or axiom schemata) and rules of inference. A theorem

6785-430: Is usually one simple criterion. The essential criterion is that the theory must be observable and repeatable. The aforementioned criterion is essential to prevent fraud and perpetuate science itself. The defining characteristic of all scientific knowledge, including theories, is the ability to make falsifiable or testable predictions . The relevance and specificity of those predictions determine how potentially useful

6900-579: The Greek language . In the book From Religion to Philosophy , Francis Cornford suggests that the Orphics used the word theoria to mean "passionate sympathetic contemplation". Pythagoras changed the word to mean "the passionless contemplation of rational, unchanging truth" of mathematical knowledge, because he considered this intellectual pursuit the way to reach the highest plane of existence. Pythagoras emphasized subduing emotions and bodily desires to help

7015-402: The modern evolutionary synthesis , etc. In addition, most scientists prefer to work with a theory that meets the following qualities: The United States National Academy of Sciences defines scientific theories as follows: The formal scientific definition of theory is quite different from the everyday meaning of the word. It refers to a comprehensive explanation of some aspect of nature that

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7130-453: The scientific method , using accepted protocols of observation , measurement, and evaluation of results. Where possible, theories are tested under controlled conditions in an experiment . In circumstances not amenable to experimental testing, theories are evaluated through principles of abductive reasoning . Established scientific theories have withstood rigorous scrutiny and embody scientific knowledge . A scientific theory differs from

7245-523: The aether's properties. An elegant theory, special relativity yielded its own consequences, such as the equivalence of mass and energy transforming into one another and the resolution of the paradox that an excitation of the electromagnetic field could be viewed in one reference frame as electricity, but in another as magnetism. Einstein sought to generalize the invariance principle to all reference frames, whether inertial or accelerating. Rejecting Newtonian gravitation—a central force acting instantly at

7360-563: The aims are different. Theoretical contemplation considers things humans do not move or change, such as nature , so it has no human aim apart from itself and the knowledge it helps create. On the other hand, praxis involves thinking, but always with an aim to desired actions, whereby humans cause change or movement themselves for their own ends. Any human movement that involves no conscious choice and thinking could not be an example of praxis or doing. Theories are analytical tools for understanding , explaining , and making predictions about

7475-513: The assumption is valid, and does not make accurate predictions when the assumption is not valid. Such assumptions are often the point with which older theories are succeeded by new ones (the general theory of relativity works in non-inertial reference frames as well). The term "assumption" is actually broader than its standard use, etymologically speaking. The Oxford English Dictionary (OED) and online Wiktionary indicate its Latin source as assumere ("accept, to take to oneself, adopt, usurp"), which

7590-426: The assumption that reality exists). However, theories do not generally make assumptions in the conventional sense (statements accepted without evidence). While assumptions are often incorporated during the formation of new theories, these are either supported by evidence (such as from previously existing theories) or the evidence is produced in the course of validating the theory. This may be as simple as observing that

7705-414: The axioms of that field. Some commonly known examples include set theory and number theory ; however literary theory , critical theory , and music theory are also of the same form. One form of philosophical theory is a metatheory or meta-theory . A metatheory is a theory whose subject matter is some other theory or set of theories. In other words, it is a theory about theories. Statements made in

7820-477: The case of embryos). Organic unity differs from contact; for in the latter case there need be nothing except contact, but in both the things which form an organic unity there is some one and the same thing which produces, instead of mere contact, a unity which is organic, continuous and quantitative (but not qualitative). Again, "nature" means (d) the primary stuff, shapeless and unchangeable from its own potency, of which any natural object consists or from which it

7935-435: The construction of mathematical theories that formalize large bodies of scientific knowledge. A theory is underdetermined (also called indeterminacy of data to theory ) if a rival, inconsistent theory is at least as consistent with the evidence. Underdetermination is an epistemological issue about the relation of evidence to conclusions. A theory that lacks supporting evidence is generally, more properly, referred to as

8050-492: The contemporary standard sense of "that which is assumed or taken for granted; a supposition, postulate" (only the 11th of 12 senses of "assumption", and the 10th of 11 senses of "assume"). Karl Popper described the characteristics of a scientific theory as follows: Popper summarized these statements by saying that the central criterion of the scientific status of a theory is its "falsifiability, or refutability, or testability". Echoing this, Stephen Hawking states, "A theory

8165-450: The discipline of medicine: medical theory involves trying to understand the causes and nature of health and sickness, while the practical side of medicine is trying to make people healthy. These two things are related but can be independent, because it is possible to research health and sickness without curing specific patients, and it is possible to cure a patient without knowing how the cure worked. The English word theory derives from

8280-400: The effective demise of logical positivism in the 1970s. The semantic view of theories , which identifies scientific theories with models rather than propositions , has replaced the received view as the dominant position in theory formulation in the philosophy of science. A model is a logical framework intended to represent reality (a "model of reality"), similar to the way that a map is

8395-586: The electromagnetic field. By omitting from special relativity the luminiferous aether , Einstein stated that time dilation and length contraction measured in an object in relative motion is inertial —that is, the object exhibits constant velocity , which is speed with direction , when measured by its observer. He thereby duplicated the Lorentz transformation and the Lorentz contraction that had been hypothesized to resolve experimental riddles and inserted into electrodynamic theory as dynamical consequences of

8510-400: The elementary theorems of a philosophical theory are statements whose truth cannot necessarily be scientifically tested through empirical observation . A field of study is sometimes named a "theory" because its basis is some initial set of assumptions describing the field's approach to the subject. These assumptions are the elementary theorems of the particular theory, and can be thought of as

8625-534: The evidence is evaluated by the scientific community, and the most important experiments will have been replicated by multiple independent groups. Theories do not have to be perfectly accurate to be scientifically useful. For example, the predictions made by classical mechanics are known to be inaccurate in the relativistic realm, but they are almost exactly correct at the comparatively low velocities of common human experience. In chemistry , there are many acid-base theories providing highly divergent explanations of

8740-446: The experimental design was sound, and if so they confirm the results by independent replication . A search for potential improvements to the theory then begins. Solutions may require minor or major changes to the theory, or none at all if a satisfactory explanation is found within the theory's existing framework. Over time, as successive modifications build on top of each other, theories consistently improve and greater predictive accuracy

8855-557: The fabrication tolerances are specified. An exploded view drawing is used to lay out the fabrication sequence. Simulation packages for displaying each of the subassemblies allow the parts to be rotated, magnified, in realistic detail. Software packages for creating the bill of materials for construction allows subcontractors to specialize in assembly processes, which spreads the cost of manufacturing machinery among multiple customers. See: Computer-aided engineering , Computer-aided manufacturing , and 3D printing An assumption (or axiom )

8970-545: The geometrical "surface" of 4D space-time. Yet unless the energy is vast, its relativistic effects of contracting space and slowing time are negligible when merely predicting motion. Although general relativity is embraced as the more explanatory theory via scientific realism , Newton's theory remains successful as merely a predictive theory via instrumentalism . To calculate trajectories, engineers and NASA still uses Newton's equations, which are simpler to operate. Both scientific laws and scientific theories are produced from

9085-442: The intellect function at the higher plane of theory. Thus, it was Pythagoras who gave the word theory the specific meaning that led to the classical and modern concept of a distinction between theory (as uninvolved, neutral thinking) and practice. Aristotle's terminology, as already mentioned, contrasts theory with praxis or practice, and this contrast exists till today. For Aristotle, both practice and theory involve thinking, but

9200-650: The level of consistent and reproducible evidence that supports them. Within electromagnetic theory generally, there are numerous hypotheses about how electromagnetism applies to specific situations. Many of these hypotheses are already considered adequately tested, with new ones always in the making and perhaps untested. Certain tests may be infeasible or technically difficult. As a result, theories may make predictions that have not been confirmed or proven incorrect. These predictions may be described informally as "theoretical". They can be tested later, and if they are incorrect, this may lead to revision, invalidation, or rejection of

9315-456: The meaning and significance of nature has been a consistent theme of discussion within the history of Western Civilization , in the philosophical fields of metaphysics and epistemology , as well as in theology and science . The study of natural things and the regular laws which seem to govern them, as opposed to discussion about what it means to be natural, is the area of natural science . The word "nature" derives from Latin nātūra ,

9430-446: The metatheory about the theory are called metatheorems . A political theory is an ethical theory about the law and government. Often the term "political theory" refers to a general view, or specific ethic, political belief or attitude, thought about politics. In social science, jurisprudence is the philosophical theory of law. Contemporary philosophy of law addresses problems internal to law and legal systems, and problems of law as

9545-434: The most reliable, rigorous, and comprehensive form of scientific knowledge, in contrast to more common uses of the word "theory" that imply that something is unproven or speculative (which in formal terms is better characterized by the word hypothesis ). Scientific theories are distinguished from hypotheses, which are individual empirically testable conjectures , and from scientific laws , which are descriptive accounts of

9660-622: The most useful properties of scientific theories is that they can be used to make predictions about natural events or phenomena that have not yet been observed. From the American Association for the Advancement of Science : A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment. Such fact-supported theories are not "guesses" but reliable accounts of

9775-490: The most useful properties of scientific theories is that they can be used to make predictions about natural events or phenomena that have not yet been observed. From the American Association for the Advancement of Science : A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment. Such fact-supported theories are not "guesses" but reliable accounts of

9890-411: The new one describes the same reality, only more completely. When a new theory uses new terms that do not reduce to terms of an older theory, but rather replace them because they misrepresent reality, it is called an intertheoretic elimination. For instance, the obsolete scientific theory that put forward an understanding of heat transfer in terms of the movement of caloric fluid was eliminated when

10005-416: The other hand, Nature or natures are ways that are "really universal" "in all times and places". What makes nature different is that it presupposes not only that not all customs and ways are equal, but also that one can "find one's bearings in the cosmos" "on the basis of inquiry" (not for example on the basis of traditions or religion). To put this "discovery or invention" into the traditional terminology, what

10120-426: The planets. For most planets, the Newtonian model's predictions are accurate; for Mercury , it is slightly inaccurate and the model of general relativity must be used instead. The word " semantic " refers to the way that a model represents the real world. The representation (literally, "re-presentation") describes particular aspects of a phenomenon or the manner of interaction among a set of phenomena. For instance,

10235-400: The possibility of faulty inference or incorrect observation. Sometimes theories are incorrect, meaning that an explicit set of observations contradicts some fundamental objection or application of the theory, but more often theories are corrected to conform to new observations, by restricting the class of phenomena the theory applies to or changing the assertions made. An example of the former is

10350-413: The previous theories as approximations or special cases, analogous to the way a theory is a unifying explanation for many confirmed hypotheses; this is referred to as unification of theories. For example, electricity and magnetism are now known to be two aspects of the same phenomenon, referred to as electromagnetism . When the predictions of different theories appear to contradict each other, this

10465-463: The proposal and testing of hypotheses , by deriving predictions from the hypotheses about the results of future experiments, then performing those experiments to see whether the predictions are valid. This provides evidence either for or against the hypothesis. When enough experimental results have been gathered in a particular area of inquiry, scientists may propose an explanatory framework that accounts for as many of these as possible. This explanation

10580-483: The real world. The theory of biological evolution is more than "just a theory". It is as factual an explanation of the universe as the atomic theory of matter or the germ theory of disease. Our understanding of gravity is still a work in progress. But the phenomenon of gravity, like evolution, is an accepted fact. Note that the term theory would not be appropriate for describing untested but intricate hypotheses or even scientific models. The scientific method involves

10695-516: The real world. The theory of biological evolution is more than "just a theory." It is as factual an explanation of the universe as the atomic theory of matter or the germ theory of disease. Our understanding of gravity is still a work in progress. But the phenomenon of gravity, like evolution, is an accepted fact. The term theory is not appropriate for describing scientific models or untested, but intricate hypotheses. The logical positivists thought of scientific theories as deductive theories —that

10810-430: The restriction of classical mechanics to phenomena involving macroscopic length scales and particle speeds much lower than the speed of light. Theory is often distinguished from practice or praxis. The question of whether theoretical models of work are relevant to work itself is of interest to scholars of professions such as medicine, engineering, law, and management. The gap between theory and practice has been framed as

10925-578: The scientific method through the formation and testing of hypotheses, and can predict the behavior of the natural world. Both are also typically well-supported by observations and/or experimental evidence. However, scientific laws are descriptive accounts of how nature will behave under certain conditions. Scientific theories are broader in scope, and give overarching explanations of how nature works and why it exhibits certain characteristics. Theories are supported by evidence from many different sources, and may contain one or several laws. A common misconception

11040-446: The speaker did not experience or test before. In science, this same concept is referred to as a hypothesis , and the word "hypothetically" is used both inside and outside of science. In its usage outside of science, the word "theory" is very often contrasted to " practice " (from Greek praxis , πρᾶξις) a Greek term for doing , which is opposed to theory. A "classical example" of the distinction between "theoretical" and "practical" uses

11155-416: The structure of a scientific theory to a "complex spatial network:" Nature (philosophy) Nature has two inter-related meanings in philosophy and natural philosophy . On the one hand, it means the set of all things which are natural, or subject to the normal working of the laws of nature . On the other hand, it means the essential properties and causes of individual things. How to understand

11270-420: The substance of natural objects; as in the case of those who say that the "nature" is the primary composition of a thing, or as Empedocles says: Of nothing that exists is there nature, but only mixture and separation of what has been mixed ; nature is but a name given to these by men. Hence as regards those things which exist or are produced by nature, although that from which they naturally are produced or exist

11385-419: The sun and the planets. These objects have associated properties, e.g., positions, velocities, and masses. The model parameters, e.g., Newton's Law of Gravitation, determine how the positions and velocities change with time. This model can then be tested to see whether it accurately predicts future observations; astronomers can verify that the positions of the model's objects over time match the actual positions of

11500-420: The term "theoretical". These predictions can be tested at a later time, and if they are incorrect, this may lead to the revision or rejection of the theory.As Feynman puts it: It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong. If experimental results contrary to a theory's predictions are observed, scientists first evaluate whether

11615-414: The term "theory" refers to "a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment." Theories must also meet further requirements, such as the ability to make falsifiable predictions with consistent accuracy across a broad area of scientific inquiry, and production of strong evidence in favor of

11730-477: The theories, if they could not be directly observed by the senses (for example, atoms and radio waves ), were treated as theoretical concepts. In this view, theories function as axioms : predicted observations are derived from the theories much like theorems are derived in Euclidean geometry . However, the predictions are then tested against reality to verify the predictions, and the "axioms" can be revised as

11845-497: The theory from multiple independent sources ( consilience ). The strength of a scientific theory is related to the diversity of phenomena it can explain, which is measured by its ability to make falsifiable predictions with respect to those phenomena. Theories are improved (or replaced by better theories) as more evidence is gathered, so that accuracy in prediction improves over time; this increased accuracy corresponds to an increase in scientific knowledge. Scientists use theories as

11960-480: The theory is. A would-be theory that makes no observable predictions is not a scientific theory at all. Predictions not sufficiently specific to be tested are similarly not useful. In both cases, the term "theory" is not applicable. A body of descriptions of knowledge can be called a theory if it fulfills the following criteria: These qualities are certainly true of such established theories as special and general relativity , quantum mechanics , plate tectonics ,

12075-449: The theory makes accurate predictions, which is evidence that any assumptions made at the outset are correct or approximately correct under the conditions tested. Conventional assumptions, without evidence, may be used if the theory is only intended to apply when the assumption is valid (or approximately valid). For example, the special theory of relativity assumes an inertial frame of reference . The theory makes accurate predictions when

12190-557: The theory. In mathematics, the term theory is used differently than its use in science ─ necessarily so, since mathematics contains no explanations of natural phenomena per se , even though it may help provide insight into natural systems or be inspired by them. In the general sense, a mathematical theory is a branch of mathematics devoted to some specific topics or methods, such as set theory , number theory , group theory , probability theory , game theory , control theory , perturbation theory , etc., such as might be appropriate for

12305-407: The truth of any one of these statements is always relative to the whole theory. Therefore, the same statement may be true with respect to one theory, and not true with respect to another. This is, in ordinary language, where statements such as "He is a terrible person" cannot be judged as true or false without reference to some interpretation of who "He" is and for that matter what a "terrible person"

12420-498: The underlying nature of acidic and basic compounds, but they are very useful for predicting their chemical behavior. Like all knowledge in science, no theory can ever be completely certain , since it is possible that future experiments might conflict with the theory's predictions. However, theories supported by the scientific consensus have the highest level of certainty of any scientific knowledge; for example, that all objects are subject to gravity or that life on Earth evolved from

12535-442: The way nature behaves under certain conditions. Theories guide the enterprise of finding facts rather than of reaching goals, and are neutral concerning alternatives among values. A theory can be a body of knowledge , which may or may not be associated with particular explanatory models . To theorize is to develop this body of knowledge. The word theory or "in theory" is sometimes used outside of science to refer to something which

12650-626: The way particular humans are is partly caused by something called "human nature" is an essential step towards Aristotle 's teaching concerning causation , which became standard in all Western philosophy until the arrival of modern science. Whether it was intended or not, Aristotle's inquiries into this subject were long felt to have resolved the discussion about nature in favor of one solution. In this account, there are four different types of cause: The formal and final cause are an essential part of Aristotle's " Metaphysics " - his attempt to go beyond nature and explain nature itself. In practice they imply

12765-468: The word theory since at least the late 16th century. Modern uses of the word theory derive from the original definition, but have taken on new shades of meaning, still based on the idea of a theory as a thoughtful and rational explanation of the general nature of things. Although it has more mundane meanings in Greek, the word θεωρία apparently developed special uses early in the recorded history of

12880-540: Was also simply used to refer to "receive into association" or "adopt into partnership". Moreover, other senses of assumere included (i) "investing oneself with (an attribute)", (ii) "to undertake" (especially in Law), (iii) "to take to oneself in appearance only, to pretend to possess", and (iv) "to suppose a thing to be" (all senses from OED entry on "assume"; the OED entry for "assumption" is almost perfectly symmetrical in senses). Thus, "assumption" connotes other associations than

12995-627: Was indeed eventually confirmed. Kitcher agrees with Popper that "There is surely something right in the idea that a science can succeed only if it can fail." He also says that scientific theories include statements that cannot be falsified, and that good theories must also be creative. He insists we view scientific theories as an "elaborate collection of statements", some of which are not falsifiable, while others—those he calls "auxiliary hypotheses", are. According to Kitcher, good scientific theories must have three features: Like other definitions of theories, including Popper's, Kitcher makes it clear that

13110-443: Was supported by sufficient evidence. Also, while new theories may be proposed by a single person or by many, the cycle of modifications eventually incorporates contributions from many different scientists. After the changes, the accepted theory will explain more phenomena and have greater predictive power (if it did not, the changes would not be adopted); this new explanation will then be open to further replacement or modification. If

13225-411: Was the distinction between the accidental properties of a thing and the substance - another distinction which has lost favor in the modern era, after having long been widely accepted in medieval Europe. To describe it another way, Aristotle treated organisms and other natural wholes as existing at a higher level than mere matter in motion. Aristotle's argument for formal and final causes is related to

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