Editing Paul Feyerabend (section)

===Philosophy of science===
====Kraft Circle, hidden variables, and no-go proofs====
During Feyerabend's PhD, he retrospectively describes himself as a "raving [[positivist]]."<ref>{{Cite book|last=Feyerabend|first=Paul K.|title=Against Method|year=1993|edition=3|pages=275}}</ref> He was the head organizer of the 'Kraft circle' which discussed many issues in the foundations of physics and on the nature of [[logical positivism#confirmation|basic statements]], which was the topic of his dissertation. In 1948, Feyerabend wrote a short paper in response to Schrödinger's paper "On the Peculiarity of the Scientific Worldview." Here, Feyerabend argued that Schrödinger's demand that scientific theories present are ''Anschaulich'' (i.e., intuitively visualizable) is too restrictive. Using the example of the development of Bohr's [[Bohr model|atomic theory]], he claims that theories that are originally unvisualizable develop new ways of making phenomena visualizable.<ref name=Feyerabend1948>{{cite journal|last=Feyerabend|first=Paul|title=The Concept of Intelligibility in Modern Physics |journal=Studies in History and Philosophy of Science Part A|volume=57|date=1948|pages= 1–3}}</ref> His unpublished paper, "Philosophers and the Physicists," argues for a naturalistic understanding of philosophy where philosophy is "petrified" without physics and physics is "liable to become dogmatic" without philosophy.<ref>{{Cite book|last1=Collodel|first1=Matteo|last2=Oberheim|first2=Eric|date=2020|title=Feyerabend's Formative Years|publisher=Springer Press|language=en|pages=475–6}}</ref>

Feyerabend's early career is also defined by a focus on technical issues within the [[philosophy of quantum mechanics]]. Feyerabend argues that [[John von Neumann|von Neumann's]] 'no-go' proof only shows that the [[Copenhagen interpretation]] is consistent with the fundamental theorems of quantum mechanics but it does not logically follow from them. Therefore, causal theories of quantum mechanics (like [[Bohmian mechanics]]) are not logically ruled out by von Neumann's proof.<ref name=Shaw20201>{{cite journal|last=Shaw |first=Jamie|title= The Revolt Against Rationalism: Feyerabend's Critical Philosophy |journal= Studies in History and Philosophy of Science Part A|volume=80|date=2020| pages= 113|doi=10.1016/j.shpsa.2019.05.007 |pmid=32383668 |bibcode=2020SHPSA..80..110S |s2cid=182010729 }}</ref> After meeting David Bohm in 1957, Feyerabend became an outspoken defender of Bohm's interpretation and argued that [[Hidden-variable theory|hidden variable]] approaches to quantum mechanics should be pursued to increase the testability of the Copenhagen Interpretation.<ref name=vanStrienl/>

Feyerabend also provided his own solution to the measurement problem in 1957, although he soon came to abandon this solution. He tries to show that von Neumann's measurement scheme can be made consistent without the [[collapse postulate]]. His solution anticipates later developments of [[quantum decoherence|decoherence theory]].<ref name=KFra>{{cite journal|last1=Kuby |first1=Daniel|last2=Fraser |first2=Patrick|title= Feyerabend on the Quantum Theory of Measurement: A Reassessment |journal= International Studies in the Philosophy of Science |date=2022|volume=35 | pages= 23–49|doi=10.1080/02698595.2022.2067811 |s2cid=251357846 |url=http://philsci-archive.pitt.edu/20036/1/kuby-fraser-feyerabend.pdf }}</ref>

====Empiricism, pluralism, and incommensurability====
Much of Feyerabend's work from the late 1950s until the late 1960s was devoted to methodological issues in science. Specifically, Feyerabend offers several criticisms of [[empiricism]] and offers his own brand of theoretical pluralism. One such criticism concerns the distinction between observational and theoretical terms. If an observational term is understood as one whose acceptance can be determined by immediate perception, then what counts as 'observational' or 'theoretical' changes throughout history as our patterns of habituation change and our ability to directly perceive entities evolve.<ref name=PKF19601>{{cite journal|last=Feyerabend |first=Paul |title= Das Problem der Existenz theoretischer Entitäten |journal= Probleme der Wissenschaftstheorie: Festschrift für Viktor Kraft |date=1960|pages=16}}</ref> On another definition, observation terms are those that can be known directly and with certainty whereas theoretical terms are hypothetical. Feyerabend argues that all statements are hypothetical, since the act of observation requires theories to justify its veridicality.<ref name=PKF19602>{{cite journal|last=Feyerabend |first=Paul |title= Das Problem der Existenz theoretischer Entitäten |journal= Probleme der Wissenschaftstheorie: Festschrift für Viktor Kraft |date=1960|pages=21}}</ref>

To replace empiricism, Feyerabend advances theoretical pluralism as a methodological rule for scientific progress. On this view, proliferating new theories increases the testability of previous theories that might be well-established by observations. This is because some tests cannot be unearthed without the invention of an alternative theory.<ref name=PKF1963>{{cite journal|last=Feyerabend |first=Paul |title= How to Be a Good Empiricist: A Plea for Tolerance in Matters Epistemological |journal= Philosophy of Science: The Delaware Seminar Volume 2|date=1963|pages=3–39}}</ref> One example Feyerabend uses repeatedly is [[Brownian motion]] which was not a test of the [[second law of thermodynamics|second law of classical thermodynamics]].<ref>{{cite journal | last=Feyerabend | first=Paul K. | date=1962 | title=Explanation, reduction, and empiricism | series=Minnesota studies in the philosophy of science | journal=Scientific Explanation, Space & Time | editor1-first=H. | editor1-last=Feigl | editor2-first=G. | editor2-last=Maxwell | location=Minneapolis | volume=3 | pages=72|hdl = 11299/184633|hdl-access=free}}</ref> To become a test, it must be first explained by an alternative theory – namely, Einstein's [[kinetic theory of gases]] – which formally contradicts the accepted theory. By proliferating new theories, we increase the number of indirect tests of our theories. This makes theoretical pluralism central to Feyerabend's conception of scientific method.

Eventually, Feyerabend's pluralism incorporates what he calls the "principle of tenacity."<ref name=PKF1968>{{cite journal|last=Feyerabend |first=Paul |title= Outline of a Pluralistic Theory of Knowledge and Action |journal= Planning for Diversity and Choice |date=1968|pages=107}}</ref> The principle of tenacity allows scientists to pursue theories regardless of the problems it may possess. Examples of problems might include recalcitrant evidence, [[paradox|theoretical paradoxes]], [[computational complexity|mathematical complexity]], or [[inconsistency]] with neighboring theories. Feyerabend learned of this idea from Kuhn, who argued that without tenacity all theories would have been prematurely abandoned.<ref name=PHH>{{cite journal|last=Hoyningen-Huene |first=Paul |title= Two letters of Paul Feyerabend to Thomas S. Kuhn on a draft of the structure of scientific revolutions |journal= Studies in History and Philosophy of Science Part A |date=1995| volume=26|issue=3|pages= 353–387|doi=10.1016/0039-3681(95)00005-8 |bibcode=1995SHPSA..26..353H }}</ref> This principle complements the "principle of proliferation", which admonishes us to invent as many theories as possible, so that those invented theories can become plausible rivals.<ref name=Shaw2017>{{cite journal|last=Shaw |first=Jamie|title= Was Feyerabend an Anarchist? The Structure(s) of 'Anything Goes'|journal= Studies in History and Philosophy of Science Part A|volume=64|date=2017| pages= 11–21|doi=10.1016/j.shpsa.2017.06.002 |pmid=29042018 |bibcode=2017SHPSA..64...11S }}</ref>

In his "Empiricism, Reduction, and Experience" (1962), Feyerabend outlines his theory of incommensurability. His theory appears in the same year as Thomas Kuhn's discussion of incommensurability in ''[[The Structure of Scientific Revolutions]]'', but the two were developed independently.<ref>{{Cite book|url=https://plato.stanford.edu/archives/fall2018/entries/incommensurability/|title=The Stanford Encyclopedia of Philosophy|first1=Eric|last1=Oberheim|first2=Paul|last2=Hoyningen-Huene|editor-first=Edward N.|editor-last=Zalta|date=February 1, 2018|publisher=Metaphysics Research Lab, Stanford University|via=Stanford Encyclopedia of Philosophy}}</ref> According to Feyerabend, some instances of theory change in the history of science do not involve a successor theory that retains its predecessor as a [[Limiting case (philosophy of science)|limiting case]]. In other words, scientific progress does not always involve producing a theory that is a [[inductive reasoning|generalization]] of the previous theory. This is because the successor theory is formally inconsistent with the previous theory attempting to explain the same domain of phenomena.<ref name="Feyerabend 1962 28–97">{{cite journal | last=Feyerabend | first=Paul K. | date=1962 | title=Explanation, reduction, and empiricism | series=Minnesota studies in the philosophy of science | journal=Scientific Explanation, Space & Time | editor1-first=H. | editor1-last=Feigl | editor2-first=G. | editor2-last=Maxwell | location=Minneapolis | volume=3 | pages=28–97|hdl = 11299/184633|hdl-access=free}}</ref> Moreover, the two theories do not share the same [[empirical evidence|empirical content]] and, therefore, cannot be compared by the same set of observation statements. For example, [[Jean Buridan|Buridan]]'s [[theory of impetus|impetus principle]] has no analogue in [[classical mechanics]]. The closest analogue would be [[momentum]], but the two notions are qualitatively distinct (impetus causes motion whereas momentum is the result of motion). Furthermore, Feyerabend claims that there can be no 'parallel notion' of impetus that is explicable within classical mechanics. Any parallel notion that gives non-zero values must assume that inertial movements happen in a resisting medium, which is inconsistent with the assumption in classical mechanics that inertial motion happens in empty space. Therefore, "the concept of impetus, as fixed by the usage established in the impetus theory, cannot be defined in a reasonable way within Newton's theory [since] the usage involves laws... which are inconsistent with Newtonian physics."<ref>{{cite journal | last=Feyerabend | first=Paul K. | date=1962 | title=Explanation, reduction, and empiricism | series=Minnesota studies in the philosophy of science | journal=Scientific Explanation, Space & Time | editor1-first=H. | editor1-last=Feigl | editor2-first=G. | editor2-last=Maxwell | location=Minneapolis | volume=3 | pages=66|hdl = 11299/184633|hdl-access=free}}</ref> In response to criticisms of Feyerabend's position, he clarifies that there are other ways in which theories can be compared such as comparing the structures of infinite sets of elements to detect [[isomorphism]]s,{{sfn|Feyerabend|1965|pp=102-103}} comparing "local grammars" ,{{sfn|Feyerabend|1965|loc=fn.32 116}} or building a [[model]] of a theory within its alternative.{{sfn|Feyerabend|1965|p=115}}  Incommensurability, however, only arises if scientists make the choice to interpret theories [[scientific realism|realistically]]. Theories interpreted [[instrumentalism|instrumentally]] cannot be incommensurable, on Feyerabend's view.

Feyerabend's pluralism is supported by what he calls the 'pragmatic theory of meaning' which he developed in his dissertation.<ref name="Kuby"/> Here, he explicitly resuscitates Neurath and Carnap's [[physicalism]] from the 1930s. According to the pragmatic theory of meaning, language consists of two parts. First, there is the characteristic of a language which is a series of noises produced under specific experimental situations. On Feyerabend's views, human observation has no special epistemic status – it is just another kind of measuring apparatus. The characteristic of a language comes from placing observers in the presence of phenomena and instructing them to make specific noises when a phenomenon is sensed. These noises, to become statements (or parts of a language with [[meaning (linguistic)|meaning]]), must then be [[language interpretation|interpreted]]. Interpretation comes from a theory, whose meaning is given is learned though not necessarily through ostension.<ref name=PKF1958>{{cite journal|last=Feyerabend |first=Paul |title= An Attempt at a Realistic Interpretation of Experience |journal= Proceedings of the Aristotelian Society|volume=58|date=1958|pages=143–170|doi=10.1093/aristotelian/58.1.143 }}</ref> Once we have an interpreted characteristic, we have statements that can be used to test theories.

====Departure from Popper====
Beginning in at least the mid-to-late 1960s, Feyerabend distanced himself from Popper both professionally and intellectually. There is a great amount of controversy about the source and nature of Feyerabend's distancing from Popper.<ref name=Collodel/> Joseph Agassi claims that it was caused by the student revolutions at Berkeley, which somehow promoted Feyerabend's move towards epistemological anarchism defended in the 1970s.<ref name=Agassi>{{cite journal|last=Agassi |first=Joseph |title= As you like it|journal= The Gentle Art of Philosophical Polemics: Selected Reviews and Comments |date=1980 |pages=422–4}}</ref> Feyerabend's friend Roy Edgley claims that Feyerabend became distanced from Popper as early as the mid-1950s, when he went to Bristol and then Berkeley and was more influenced by Thomas Kuhn and the [[Marxism]] of David Bohm.<ref name=Edgley>{{cite journal|last=Edgley |first=Roy|title= Anarchy in Academia |journal= New Left Review| pages= 155–156}}</ref>

Feyerabend's first paper that explicitly repudiates Popper is his two-part paper on Niels Bohr's conception of [[Complementarity (physics)|complementarity]].<ref name=PKF19682>{{cite journal|last=Feyerabend |first=Paul |title= On a Recent critique of complementarity: part I |journal= Philosophy of Science |date=1968| volume=35|issue=4|pages= 309–331|doi=10.1086/288226 |s2cid=170776675 }}</ref> According to Popper, Bohr and his followers accepted complementarity as a consequence of accepting positivism. Popper was the founder of the theory of falsification, which Feyerabend was very critical of. He meant that no science is perfect, and therefore cannot be proven false.<ref>{{cite book |last1=Andreasson and Johansson |first1=Jesper and Thomas |title=Vetenskapsteori: grunder och tillämpning |date=2020 |publisher=Studentlitteratur |location=Lund |isbn=978-91-44-18508-8 |pages=66–67 |edition=2nd}}</ref> Once one repudiates positivism as a philosophical doctrine, Popper claims, one undermines the principle of complementarity. Against this, Feyerabend claims that Bohr was a pluralist who attempting to pursue a realistic interpretation of quantum mechanics (the [[BKS theory|Bohr-Kramer-Slater conjecture]]) but abandoned it due to its conflict with the Bothe-Geiger and Compton-Simon experiments.<ref name=Shaw2018>{{cite journal | last = Shaw | first = Jamie | title = A Pluralism Worth Having: Feyerabend's Well-Ordered Science | journal = Electronic Thesis and Dissertation Repository | publisher = University of Western Ontario (doctoral dissertation) | year = 2018 | pages=38 |url = https://ir.lib.uwo.ca/etd/5599/}}</ref> While Feyerabend concedes that many of Bohr's followers (notably, [[Leon Rosenfeld]]) accept the principle of complementarity as a philosophical dogma, he contends that Bohr accepted complementarity because it was entangled with an empirically adequate physical theory of microphysics.

====Anarchist phase====
{{See also|Against Method}}
In the 1970s, Feyerabend outlines an anarchistic theory of knowledge captured by the slogan 'anything goes'. The phrase 'anything goes' first appears in Feyerabend's paper "Experts in a Free Society" and is more famously proclaimed at the end of the first chapter of ''Against Method''.<ref name=Shaw20171>{{cite journal|last=Shaw |first=Jamie|title= Was Feyerabend an Anarchist? The Structure(s) of 'Anything Goes'|journal= Studies in History and Philosophy of Science Part A|volume=64|date=2017| pages= 14|doi=10.1016/j.shpsa.2017.06.002 |pmid=29042018 |bibcode=2017SHPSA..64...11S }}</ref> Feyerabend's epistemological anarchism has been the source of contention amongst scholars. Some claim that epistemological anarchism is not a positive view of scientific method, but the conclusion of a [[reductio ad absurdum]] of 'rationalism' (the view that there are universal and unchanging rational rules for scientific reasoning). In Feyerabend's words, {{"'}}anything goes' is not a 'principle' I hold... but the terrified exclamation of a rationalist who takes a closer look at history."<ref>{{Cite book|last=Feyerabend|first=Paul K.|title=Against Method|year=1975|edition=1|pages=xvii}}</ref> On this interpretation, Feyerabend aims to show that no methodological view can be held as fixed and universal and therefore the only fixed and universal rule would be "anything goes" which would be useless.

On another interpretation, Feyerabend is claiming that scientists should be [[opportunism|unscrupulous opportunists]] who choose methodological rules that make sense within a given situation.<ref name=Shaw2017/> On this view, there are no 'universal' methodological rules but there are local rules of scientific reasoning that should be followed. The use of the phrase 'opportunism' comes from Einstein<ref name=Howard>{{cite journal|last=Howard |first=Don |title= Astride the Divided Line: Platonism, Empiricism, and Einstein's Epistemological Opportunism |journal= Poznan Studies in the Philosophy of the Sciences and the Humanities |date=1998| volume=63|pages= 143–164}}</ref> which denotes an inquirer who changes their beliefs and techniques to fit the situation at hand, rather than pre-judge individual events with well-defined methods or convictions. Feyerabend thinks that this is justified because "no two individuals (no two scientists; no two pieces of apparatus; no two situations) are ever exactly alike and that procedures should therefore be able to vary also."<ref name=Feyerabend19701>{{cite journal|last=Feyerabend |first=Paul|title= Experts in a Free Society |journal= The Critic| volume = 29| issue = 2|pages= 122–123}}</ref>

On a third interpretation, epistemological anarchism is a generalization of his pluralism that he had been developing throughout the 1950s and 1960s.<ref name=Shaw2017/> On this view, Feyerabend did not have an anarchist 'turn' but merely generalized his positive philosophy on a more general view. Epistemological anarchism is synonymous with a pluralism without limits, where one can proliferate any theory one wishes and one can tenaciously develop any theory for as long as one wishes. Relatedly, because methods depend on empirical theories for their utility, one can employ any method one wishes in attempt to make novel discoveries. This does not mean that we can believe anything we wish – our beliefs must still stand critical scrutiny – but that scientific inquiry has no intrinsic constraints.<ref name=Shaw20172>{{cite journal|last=Shaw |first=Jamie|title= Was Feyerabend an Anarchist? The Structure(s) of 'Anything Goes'|journal= Studies in History and Philosophy of Science Part A|volume=64|date=2020| pages= 19}}</ref> The only constraints on scientific practice are those that are materially forced upon scientists. Moreover, Feyerabend also thought that theoretical anarchism was desirable because it was more [[humanitarian]] than other systems of organization, by not imposing rigid rules on scientists.

<blockquote>For is it not possible that science as we know it today, or a "search for the truth" in the style of traditional philosophy, will create a monster? Is it not possible that an objective approach that frowns upon personal connections between the entities examined will harm people, turn them into miserable, unfriendly, self-righteous mechanisms without charm or humour? "Is it not possible," asks Kierkegaard, "that my activity as an objective [or critico-rational] observer of nature will weaken my strength as a human being?" I suspect the answer to many of these questions is affirmative and I believe that a reform of the sciences that makes them more anarchic and more subjective (in Kierkegaard's sense) is urgently needed. ''Against Method'' (3rd ed.). p. 154.<ref>{{Cite book|last=Feyerabend|first=Paul K.|title=Against Method|year=1993|edition=3|pages=154}}</ref></blockquote>

According to this "[[existentialism|existential criteria]]",<ref name=Martin>{{cite journal|last=Martin |first=Eric |title= Late Feyerabend on materialism, mysticism, and religion |journal= Studies in History and Philosophy of Science Part A |date=2016| volume=57|pages= 129–136|doi=10.1016/j.shpsa.2015.11.017 |pmid=27269272 |bibcode=2016SHPSA..57..129M }}</ref> methodological rules can be tested by the kinds of lives that they suggest. Feyerabend's position was seen as radical, because it implies that philosophy can neither succeed in providing a general description of science, nor in devising a method for differentiating products of science from non-scientific entities like [[myths]].

To support his position that methodological rules generally do not contribute to scientific success, Feyerabend analyzed counterexamples to the claim that (good) science operates according to the methodological standards invoked by philosophers during Feyerabend's time (namely, inductivism and falsificationism). Starting from episodes in science that are generally regarded as indisputable instances of progress (e.g. the [[Copernican Revolution]]), he argued that these episodes violated all common prescriptive rules of science. Moreover, he claimed that applying such rules in these historical situations would actually have prevented scientific revolution.<ref>{{Cite book|last=Feyerabend|first=Paul K.|title=Against Method|year=1993|edition=3|pages=14–15|quote=the Copernican Revolution [...] occurred only because some thinkers either decided not to be bound by certain 'obvious' methodological rules, or because they unwittingly broke them. [...] There are even circumstances - and they occur rather frequently when argument loses its forward-looking aspect and becomes a hindrance to progress.}}</ref> His primary case study is [[Earth's rotation|Galileo's hypothesis that the Earth rotates on its axis]].

====Metaphysics of abundance====
{{See also|Conquest of Abundance}}
In Feyerabend's later work, especially in ''Conquest of Abundance'', Feyerabend articulates a [[metaphysics|metaphysical theory]] in which the universe around us is 'abundant' in the sense that it allows for many realities to be accepted simultaneously. According to Feyerabend, the world, or 'Being' as he calls it, is pliable enough that it can change in accordance with the ways in which we causally engage with the world.<ref name=PKF1999>{{cite book | last = Feyerabend | first = Paul | title = Conquest of Abundance| publisher = University of Chicago Press | year = 1999 | pages = 145}}</ref> In [[laboratories]], for example, scientists do not simply passively observe phenomena but actively intervene to create phenomena with the help of various techniques. This makes entities like '[[electrons]]' or '[[genes]]' real because they can be stably used in a life that one may live. Since our choices about what lives we should live depend on our ethics and our desires, what is 'real' depends on what plays a role in a life that we think is worth living. Feyerabend calls this 'Aristotle's principle' as he believes that Aristotle held the same view.<ref name=Brown2016>{{cite journal|last=Brown |first=Matthew J.|title= The abundant world: Paul Feyerabend's metaphysics of science |journal= Studies in History and Philosophy of Science Part A |date=2016| volume=57|pages= 142–154|doi=10.1016/j.shpsa.2015.11.015 |pmid=27269274 |bibcode=2016SHPSA..57..142B }}</ref>

Being, therefore, is pliable enough to be manipulated and transformed to make many realities that conform to different ways of living in the world.<ref name=Tambolo>{{cite journal|last=Tambolo |first=Luca |title= Pliability and resistance: Feyerabendian insights into sophisticated realism |journal= European Journal for Philosophy of Science |date=2014| volume=4|issue=2|pages= 197–213|doi=10.1007/s13194-014-0082-9 |s2cid=256071558 }}</ref> However, not all realities are possible. Being resists our attempts to live with it in certain ways and so not any entity can be declared as 'real' by mere stipulation. In Feyerabend's words,

<blockquote> "I do not assert that any [form of life] will lead to a well-articulated and livable world. The material humans...face must be approached in the right way. It offers resistance; some constructions (some incipient cultures - [[Cargo cult|cargo cults]], for example) find no point of attack in it and simply collapse"<ref name=PKF1989>{{cite journal|last=Feyerabend |first=Paul |title= Realism and the Historicity of Knowledge |journal= The Journal of Philosophy |date=1989| volume=86|issue=8|pages= 393–406|doi=10.2307/2026649 |jstor=2026649 }}</ref> </blockquote>

This leads Feyerabend to defend the disunity of the world thesis that was articulated by many members of the Stanford School. There are many realities that cannot be reduced to one common 'Reality' because they contain different entities and processes.<ref name=Brown2009>{{cite journal|last=Brown |first=Matthew J.|title= Models and perspectives on stage: remarks on Giere's scientific perspectivism |journal= Studies in History and Philosophy of Science Part A |date=2009| volume=40|issue=2|pages= 219|doi=10.1016/j.shpsa.2009.03.001 |bibcode=2009SHPSA..40..213B }}</ref> This makes it possible that some realities contain gods while others are purely materialistic, although Feyerabend thought that materialistic worldviews were deficient in many unspecified ways.<ref name=Martin/>

Feyerabend's ideas about a 'conquest of abundance' were first voiced in ''Farewell to Reason'', and the writings of the late 1980s and early 1990s experiment with different ways of expressing the idea, including many of the articles and essays published as part two of ''Conquest of Abundance''. A new theme of this later work is the ineffability of Being, which Feyerabend developed with reference to the work of the Christian mystic, [[Pseudo-Dionysius the Areopagite]]. The remarks on ineffability in ''Conquest of Abundance'' are too unsystematic to definitively interpret.