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|SummaryBrief='''Imre Lakatos''' (1922–1974) was a Hungarian-born philosopher of science who studied greatly contributed to the problem of demarcation criteria and theory choice in science.[[CiteRef::Musgrave and Pigden (2016)]][[CiteRef::Chalmers (2013)]] |Summary=A protege of [[Karl Popper]], Lakatos attempted to respond to problems posed by the work of Popper and [[Thomas Kuhn|Kuhn]]. [[CiteRef::Musgrave and Pigden (2016)]][[CiteRef::Chalmers (2013)]] His [[Lakatos (1970)|''Methodology of Scientific Research Programmes'']] (MSRP) offers a holistic approach to theory choice which extends beyond Popper's falsificationism, and instead . It assesses a particular research program as progressive or degenerative, depending on its overall record of predictive and explanatory successes and failures. Lakatos later entered into a correspondence with [[Paul Feyerabend]], with the goal of addressing Feyerabend’s objections to the MSRP. He met an untimely death due to a heart attack at the age of 51. Some of Feyerabend’s objections remain challenging to this day.|Historical Context=Much of Lakatos’ Lakatos's work was a response to the problems of Popper’s [[Karl Popper]]’s '''falsificationism''', which and was expressed in a series of works published publications between 1935 and the early 1970's. Lakatos rejected the idea that a false prediction was alone grounds for rejecting a theory. Most theories, he pointed out, are born in an “ocean of anomalies” and are therefore falsified from the moment of their inception. For example, Copernican heliocentric astronomy predicts that the stars should change in apparent position as the Earth revolves around the sun, but for three centuries after Copernicus proposed his theory, all attempts to detect this stellar parallax failed. Astronomers nevertheless accepted the theory on other grounds. The failure of Newtonian mechanics to account for the motions of the planet Mercury was known for many decades, during which the theory also wasn't rejected.[[CiteRef::Musgrave and Pigden (2016)]] A well known criticism of falsificationism, attributed to the [[Pierre Duhem|Duhem and ]]-Quinethesis, and which Lakatos [[CiteRef::Stanford (2016)]][[CiteRef::Duhem (1962)]][[CiteRef::Quine (1951)]] which Lakatos championed, was that the failure of a prediction could be due to a problem anywhere in the network of theories and auxiliary assumptions responsible for that prediction. Lakatos thus argued that Popper's theory was overly restrictive and inconsistent with much of scientific practice. In scientific practice, Lakatos observed that if a theory is the best available of its kind, it is typically allowed to undergo modifications to account for all data and not rejected.

Lakatos also responded to Thomas Kuhn’s ''Structure of Scientific Revolutions'', published in 1962. [[CiteRef::Kuhn (1962a)]] He was troubled by Kuhn's '''incommensurability thesis''', which asserts that theories with different taxonomies cannot be rationally compared. Lakatos accused Kuhn of depicting the process of scientific change as completely irrational. If there truly existed a problem of incommensurability in science, then there would be no method to demarcate between science and pseudoscience, and no way of measuring scientific progress.[[CiteRef::Lakatos (1978a)]] HoweverAt the same time, like Lakatos and Kuhn's views of science have important points in common. Both rejected the positivist, inductivist accounts of science popular in the early twentieth century, Lakatos believed and both emphasized the importance of theory over observation. Both agreed that any theory of how science works must make sense of the actual history of science.[[CiteRef::Chalmers (2013)|pp. 103-114]]

Following the Duhem-Quine-Duhem thesis, Lakatos recognized that scientific theories could not be appraised individually. Rather, all of the theoretical assumptions bearing on an experimental finding had to be assessed holistically, in terms as parts of what he called a '''research program'''.[[CiteRef::Lakatos called (1970)|pp. 31-55]] While Kuhn supposed that, in a mature scientific discipline, only one paradigm generally existed at a "time, Lakatos argued that it was generally the case that more than one research program"existed in a field at any given time, and that large-scale processes of scientific change should be understood as competition between research programs. [[CiteRef::Godfrey-Smith (2003)|pp. 102-121]] Within a research program, not all theoretical assumptions are treated equally. It contains a "hard core" of The indispensable central theoretical assumptions, which are its indispensable constituents. Any modification of the "hard core" results in the creation of a new research program. Adherents of a research program attempt to explain an increasingly wide range of relevant natural phenomena in terms of the core. In so doing, they create a "protective belt" of auxiliary propositions. This expansion of the range of applicability of the program constitutes are its "positive heuristic". Scientists committed to a research program defend the "'''hard core" against change by using their ingenuity as needed to make alterations to the "protective belt" of auxiliary propositions to explain phenomena and avoid falsification of the core'''. This protection Any modification of the hard core is a research program's "negative heuristic". For example, constitutes the "hard core" abandonment of the Newtonian physics research program would consist of Newton's three laws of motion and Law of Universal Gravitation. The protective belt would include propositions such as "the Earth is an oblate spheroid" or "Neptune is 17 times more massive than Earth". In the nineteenth century, astronomers could not explain the movements creation of the planet Uranus using Newton's theory and known gravitational influences. Rather than modifying the theory itself, which would have obviated the Newtonian research program, they modified the protective belt by positing the existence of a new planet, whose Newtonian gravitational influence was affecting Uranus. The prediction was a stunning success, as the new planet, to be named Neptune, was discovered in 1846one.[[CiteRef::Chalmers (2013)|pp. 103-114]][[CiteRef::Lakatos (1978a1970)|pp. 31-55]]

Lakatos held Auxiliary propositions that are relevant to the hard core, but are not part of it form a research programme should be chosen for both its “explanatory power” and its “heuristic power”'''protective belt'''. That is to say that Adherents of a theory is accepted for its ability research program attempt to both explain past and present an increasingly wide range of relevant natural phenomenain terms of the core. In so doing, as well as its ability they add to be applied to and posit the existence protective belt of auxiliary propositions. This expansion of the range of applicability of future phenomena and anomaliesthe program constitutes its '''positive heuristic'''. Given any evidence Scientists committed to a research program defend the hard core against a theory, if change by using their ingenuity as needed to make alterations to the theory possesses both greater heuristic and explanatory powers than its counterparts, its protective belt should be allowed of auxiliary propositions to undergo modifications explain phenomena and avoid falsification. These modifications should be “progressive” and intended to save of the research programme from degeneratingcore. This, for Lakatos, represents protection of the difference between falsification and rejection.A hard core is a research programme is considered “progressive” if it can make predictions later confirmed by experiment, much in line with the Popperian notion of program's '''negative heuristic'novel predictions''. On the other hand, if a theory fails to offer such predictions and merely attempts to “save” itself from a disproving instance, it is considered “degenerative”[[CiteRef::Lakatos (1970)|pp. 47-51]]

Lakatos stipulates that a modification is '''progressive''' if ''all'' of the following conditions are met: * The modification has some excess empirical contentFor example, i.e. it increases the overall empirical content hard core of a the Newtonian physics research programme (by making novel predictions or increasing their precision program would consist of Newton's three laws of motion and accuracy).* Some Law of this excess empirical content has been corroborated in experiments and observationsUniversal Gravitation.* The modification protective belt would include propositions such as "the Earth is in organic unity with an oblate spheroid" or "Neptune is 17 times more massive than Earth". In the nineteenth century, astronomers could not explain the rest movements of the programmeplanet Uranus using Newton's theory and known gravitational influences. ThusRather than modifying the theory itself, according to Lakatoswhich would have obviated the Newtonian research program, there are three types of regressive (''ad hoc'') modifications. A modification is '''regressive''' if at least one of they modified the following obtains:* It does not increase protective belt by positing the empirical content existence of the programmea new planet, iwhose Newtonian gravitational influence was affecting Uranus.e. it doesn't make novel predictions or increase their precision/accuracy (''ad hoc₁'').* It introduces excess empirical contentThe prediction was a stunning success, as the new planet, but fails to corroborate any of this excess content empirically be named Neptune, was discovered in 1846.[[CiteRef::Chalmers (''ad hoc₂''2013)|pp.* it is not in organic unity with the rest of the programme 103-114]][[CiteRef::Lakatos (''ad hoc₃''1970)|pp.31-48]]

If any evidence is found against a theory, and if the theory otherwise possesses both greater heuristic and explanatory powers than known alternatives, Lakatos supposed that falsification should be averted by modifying the research program's protective belt. There thus can be no 'crucial experiments'; a research program cannot be instantly overthrown by a single experimental finding taken in isolation.  Lakatos held that a research program should be evaluated in terms of both its explanatory power; its ability to explain known phenomena, and its heuristic power; its ability to successfully explain newly discovered phenomena or to predict their existence.  Lakatos stipulated that a modification is '''progressive''' if ''all'' of the following conditions are met:[[CiteRef::Lakatos (1970)|pp. 31-34]] # the modification has some excess empirical content, i.e. it increases the overall empirical content of a research programme (by making novel predictions or increasing their precision and accuracy);# some of this excess empirical content has been corroborated in experiments and observations;# the modification is in organic unity with the rest of the programme.  Thus, according to Lakatos, there are three types of regressive (''ad hoc'') modifications. A modification is '''regressive''' if at least one of the following obtains:[[CiteRef::Lakatos (1971a)|pp. 112, n. 2]]# it does not increase the empirical content of the programme, i.e. it doesn't make novel predictions or increase their precision/accuracy (''ad hoc₁'');# it introduces excess empirical content, but fails to corroborate any of this excess content empirically (''ad hoc₂'');# it is not in organic unity with the rest of the programme (''ad hoc₃''). The term ''organic unity'' is intended to mean that modifications should be contiguous with the rest of the programmeprogram. For instance, if the research programme program is “natural selection”Darwin's theory of natural selection, a modification which adds the proposition “extra"extra-terrestrial beings intervened with human evolution” evolution" would not be contiguous – not in organic unity – with the rest of the research programme program, and is therefore ''ad hoc₃''regressive.


The demarcation between “progressive” "progressive" and “degenerative” "degenerative" research programmes also serves to demarcate between science and pseudoscience. A scientific theory should not only explain past and present phenomena; it should also have the ability to be applied to and posit the existence of future phenomena. For example, proving that an object falls in an experiment does not make the Newtonian research programme scientific. However, the Newtonian research programme predicted that comets move in either hyperbolas, parabolas or ellipses (contrary to the contemporary theory that they move in straights lines). Using this hypothesis, Edmond Halley successfully predicted the return of Halley’s comet to the minute. Such predictions affirm that the Newtonian research programme was progressive and, therefore, scientific. On the other hand, a research programme such as astrology, which merely provides ''post hoc '' explanations and is subject to ''ad hoc'' modifications, is considered pseudoscientific.

|Page Status=Review Needed|Related Articles=[[Karl Popper]] [[Thomas Kuhn]] [[Paul Feyerabend]] [[Larry Laudan]]Editor Approved