THOMAS KUHN ON REVOLUTION AND PAUL FEYERABEND
BOOK VI - Page 6
Feyerabend on Semantic Incommensurability
Feyerabend’s later and more comprehensive statement of his incommensurability thesis is set forth in chapter seventeen and in a brief appendix in his Against Method. The centrality of the incommensurability thesis to his philosophy is indicated by the fact that this chapter and its immediately following appendix pertaining to his incommensurability thesis, take up approximately seventy pages of this three hundred page book. Later in his Science and a Free Society (1978) he emphasizes that his intent in the discussion of incommensurability is to understand the changes that take place when a new world view enters the scene, and that this requires examining it from the perspective of the concerned parties, and not as it appears or is projected onto a later ideology years afterwards.
The significance of incommensurability is that the concerned parties experiencing it cannot subject the new idea to what they regard as rationality, and they must allow the idea of “reason” that is accessible to them to be violated. He views this analysis “from the inside” to be of the utmost practical importance, because it is what occurs in a scientific revolution, and every researcher should be prepared for such events, which would otherwise catch the researcher by surprise.
In the opening sentence of chapter seventeen of Against Method Feyerabend says that he has much sympathy with the clearly and elegantly formulated view of Whorf, and he gives a brief summary of Whorf’s principle of linguistic relativity. In the appendix following the chapter he notes that Whorf’s principle admits to two alternative interpretations. On one interpretation it means that observers using widely different languages will posit different facts in the same physical circumstances in the same physical world. On the other interpretation it means merely that observers using widely different languages will arrange similar facts in different ways.
The former interpretation is the one that Feyerabend says he uses for his own incommensurability thesis, and he justifies this interpretation on the basis of the great influence that Whorf ascribes to grammatical categories and especially to the hidden “rapport system” of language. The covert classifications that result from this hidden rapport system or “central exchange” create patterned resistances to widely divergent points of view. Feyerabend says that if these resistances oppose not just the truth of the resisted alternative views, but the presumption that an alternative has been presented, then we have in instance of incommensurability. This is the closest that Feyerabend comes to a definition of incommensurability, because as he says, it is hardly ever possible to give explicit definition of it, since it depends on covert classifications and major conceptual changes.
The body of Feyerabend’s chapter discussing incommensurability is organized into three theses, which are summarized at the end. His first thesis is that there are in fact frameworks of thought which are incommensurable, and he emphasizes that this is an anthropological thesis. Whorf was an amateur although accomplished cultural anthropologist. Feyerabend maintains that Whorf’s principle of linguistic relativity applies to scientific theories such as Aristotle’s theory of motion, the theory of relativity, the quantum theory and classical and modern cosmology, because they are sufficiently “deep” and have developed in sufficiently complex ways that they may be viewed as widely divergent and incommensurable natural languages. He therefore also maintains that philosophy of science is anthropology of science and not logic of science as both the positivists and Popper had maintained.
In the examination of the incommensurable theories, where facts asserted by each cannot be compared side by side even in memory, it is necessary to take the approach of the field linguist and learn the new theory from scratch. The irrationality of the transition to the new theory is overcome by the determined production of nonsense until the material produced is rich enough to permit recognition of new universal principles. The initial madness turns to sanity provided that it is sufficiently rich and sufficiently regular to function as the basis of a new world view. There is no translation involved; instead there is a learning process. This is how Feyerabend sees the transition from classical mechanics to quantum mechanics and from Newtonian mechanics to relativity theory.
His second thesis is that incommensurability has an analogue in the psychology of perception, and that the development of perception and thought in the individual passes through stages that are mutually incommensurable. This is contrary to the positivist philosophy of observation, and Feyerabend references Piaget’s work with perceptual development in children.
His third thesis is that scientific theories may be incommensurable even when they apparently treat of the same subject matter and the same problem. On a realistic interpretation, as opposed to an instrumentalist interpretation, incommensurable theories do not treat the same subject matter. A new theory such as relativity theory in physics does not treat the same problem that is treated by its predecessor, Newtonian mechanics, when the former replaced the latter. The new theory does not “solve” problems confronting the old theory, but rather it “dissolves” them and removes them from the domain of legitimate inquiry, because the new incommensurable theory has an ontology that replaces that of the older theory. When the faulty ontology of the older theory is comprehensive, as in the Newtonian physics, then every description inside the domain must be changed; it must be replaced by a different statement in the new theory or it may be replaced by no statement at all. The new ontologies of relativity theory and quantum theory do not just deny the existence of classical states of affairs; they do not even permit us to formulate statements expressing such states of affairs.
Crucial experiments are therefore impossible, because one theory cannot establish or refute another theory incommensurable with the former. Each incommensurable theory has its own facts, and it can be refuted only by reference to its own kind of experience, that is to say, by discovering its internal contradictions. Their contents cannot be compared. Aside from internal inconsistency, the only basis for preference for one of several mutually incommensurable theories is subjective, such as the scientist’s metaphysical prejudices, religious convictions, or personal tastes.
Feyerabend on Scientific Anarchy
In Science and a Free Society Feyerabend says in a section containing some autobiographical notes, that Carl Friedrich von Weizsacker has “prime responsibility” for Feyerabend’s change to his anarchistic view. In the days that Feyerabend was supporting Bohm’s views, he met with von Weizsacker in Hamburg in 1965 and discussed the foundations of quantum theory. Feyerabend complained that alternatives to quantum theory have been ignored, but Weizsacker showed how quantum mechanics arose from concrete research. Feyerabend relates that it then became clear to him that general methodological rules imposed without regard to circumstances are a hindrance rather than a help, and that a person must be given complete freedom with no restrictions by any norms or demands regardless of how plausible they may seem to logicians and philosophers. Feyerabend concluded that such norms and demands must be checked by research, and not by appeal to ideas of rationality. Thus did Feyerabend come to advocate scientific anarchy.
In Against Method (1975), Feyerabend’s first book, he expounds his philosophy in terms of this political phrase, “scientific anarchy”, which he fully intends to be intellectually more radical than Kuhn’s phrase, “scientific revolution”. Feyerabend’s phrase includes his principles of tenacity and theory-proliferation to which he adds an antimethodological practice which he calls “counterinduction”, a concept of scientific development that is opposed both to the logical positivist critical method of confirmation and also to Popper’s critical method of corroboration. Counterinduction is opposed to all concepts of scientific rationality and methodology in which criticism is intended to eliminate some scientific theories as incorrect. Feyerabend advocates scientific anarchy, because he denies that there is any method or concept of rationality that is adequate to the history of successful science in any sense of the term. He is against all methodologies, because there is no methodological rule that has not been violated, and these violations are necessary for the advancement of science. The only rule that he admits is “anything goes”. There is no institutional aim of science in his view, but instead each scientist may formulate his own individual aim of science, and “progress” may mean anything that one may wish.
In Feyerabend’s view scientific knowledge is an ever-increasing “ocean” of mutually incompatible and even incommensurable theories with each theory forcing the others into greater articulation. In this view counterinduction aims to introduce and to elaborate hypotheses, which are inconsistent with well established theories and with well established facts. This perpetual pluralism is possible, because even the worthiest theory has many anomalies where it does not fit the facts, while at the same time all factual statements contain theoretical assumptions. Not only is every factual description dependent on some theory, but there are also facts that cannot be unearthed except with the help of alternatives to the theory to be tested. These facts are unavailable so long as such alternative theories are excluded. In Feyerabend’s view the practice of scientific research must not contain any rules requiring either consistency with so-called confirmed theories or with the choice between falsified and nonfalsified theories. The ocean of anomalies that always surrounds every theory is concealed by ad hoc hypotheses and by ad hoc approximations that are not the result of limited measurement accuracy, but which are adjustments to cope with for complicated cases.
Feyerabend illustrates counterinduction in the history of science with an examination of Galileo’s defense of the Copernican theory against Aristotelian critics. In Science and a Free Society Feyerabend says that his views on Galileo expressed in Against Method are influenced ironically by Philipp Frank, a logical positivist and member of the Vienna Circle. The relevant Aristotelian criticism is the “tower argument”, according to which a stone dropped from a high tower would not fall vertically to the ground if the earth were in motion as Copernicus’ theory says it is, because the movement of the earth during the time of free fall would make the object fall at an angle away from the direction of the earth’s rotational movement. Feyerabend calls the observation of vertical fall of the stone a “natural interpretation” of the observation statement describing the motion of a falling stone, because the observational sensations are firmly associated with the linguistic expression of the observation statement. And he says that it is very difficult to detect error in natural interpretations without alternative statements. In his examination of Galileo’s reply to the tower argument Feyerabend maintains that Galileo used the Copernican theory to supply an alternative observational interpretation, and that Galileo’s reply was a reinterpretation of the Aristotelian natural interpretation. In this manner Galileo appealed to the “real” motion of the falling stone, by which he meant the stone’s movement relative to absolute space. Galileo distinguished between Copernican and Aristotelian motion, and characterized them as “real” and “apparent” motions respectively, arguing they are not the same.
Galileo’s reply to the tower argument is an example of counterinduction. When a theory such as the Copernican theory is contradicted by facts, the counterinductive response is to turn around the situation and to use the theory as what Feyerabend calls a “detection device”. This procedure consists firstly of affirming the truth of the new theory, and then of inquiring what changes in the facts will remove the contradiction between fact and theory. In this way hidden ideological components in the observation language expressing the facts are disclosed counterinductively. Once these ideological components are disclosed, the next step is to create a new observation language for the new theory. This is what Galileo did, and he used some propaganda to disguise that fact that he had invented the new observation language himself. His propaganda consisted in arguing that the human senses notice only relative motion, while the senses fail to notice motion that is common to such objects as falling stones and the earth, and he also used the ad hoc hypothesis based on the Copernican theory that the earth is in permanent motion. Galileo believed in the truth of the Copernican theory, and he looked for facts that supported that theory. One such supporting fact is the one resulting from his reinterpretation of observed experience, such as the falling stone. Galileo changed the conceptual component in observed fact.
Another revision of fact results from Galileo’s invention and use of the telescope. Feyerabend says that Galileo did not know enough optical theory to enable the telescopic phenomena to function as independent evidence for the Copernican theory. Use of the telescope for celestial observation was also problematic to the Aristotelians, and what Galileo did was to use the agreement between the Copernican theory and the telescopic observation to argue on behalf of both of these views. The use of telescopic phenomena as evidence for the Copernican theory had to await the further development of the auxiliary science of optics.
Neither the telescopic phenomena nor the new idea of relative motion were acceptable to common sense at the time or to the Aristotelians, and the two associated ideas both seemed false. Yet these seemingly false and unacceptable phenomena were distorted by Galileo, and converted into strong support for Copernicus. Galileo replaced old facts with a new type of experience, which he simply invented for the purpose of supporting Copernicus, and he let apparently refuted theories support one another, in order to create a new world view. Feyerabend maintains that Galileo’s arguments violate basic rules of scientific method, which were invented by Aristotle and canonized by the positivists, such as Carnap and Popper. (Feyerabend occasionally calls Popper a positivist.) And he states that Galileo succeeded precisely because he did not follow these rules. Had Galileo followed these methodological rules, he would have failed.
Feyerabend’s general thesis is that every methodological rule is associated with cosmological assumptions, so that using that rule implies that the cosmology in which it originates is correct. The rule that the Copernican theory must be tested is reasonable, but requiring that it be tested by confronting it with the status quo is not reasonable. What is reasonable is the purportedly “irrational” practice of waiting and ignoring large masses of critical observations and measurements, because the Copernican theory is an entirely new worldview. It is necessary to retain the new cosmology, until it has been supplemented with the necessary auxiliary sciences, so that the language in which observations are expressed may be revised.
Feyerabend finds what he illustrates with Galileo to be no less applicable today. He says that today’s rational sciences survived, because irrational “prejudices” were permitted to have their way, and that it is advisable to let one’s inclinations go against reason in many circumstances. Propaganda is of the essence. Science is more sloppy and irrational than its methodological image. Anarchistic deviations from rationality are necessary for progress. The image of twentieth-century science is created by technological successes together with a “fairy tale” of how these technological miracles were accomplished. The fairy tale is that science is not an ideology, but rather is an objective measure for all ideologies. Feyerabend maintains that science is an ideology, and that successful science is very much a result of good luck and false beliefs. His thesis of scientific anarchy moves him far along in the direction of historical relativism. But the centrality of historical relativism in his philosophy of science is not fully evident without examination of the lengthy evolution of his philosophy of quantum theory and of realism.
Feyerabend on Quantum Theory
From the time of his writing his dissertation in 1951, Feyerabend’s philosophy of science was centered on the reconciliation of metaphysical realism with modern microphysics. The development of his thought on this matter might be viewed as a case of the moth and the flame, where the circling moth is Feyerabend’s realistic philosophy and the consuming flame is Bohr’s peculiar Copenhagen interpretation of the quantum theory. Initially he was critical of the Copenhagen interpretation, and particularly both of Bohr’s instrumentalist view of the quantum theory’s formalism and of Bohr’s complementarity thesis. Feyerabend received his views on metaphysical realism from Popper, but Feyerabend did not agree with Popper’s attempt to supply the current quantum-theoretic formalism with the propensity interpretation, although it is an interpretation in classical physics. Instead Feyerabend defended the possibility of an altogether new microphysical theory.
In the 1960’s Feyerabend became involved in a long debate with Norwood Russell Hanson. As a result he reconsidered the merits of the current quantum theory, and the accepted likelihood of its duality thesis and its quantum postulate being carried forward into a future microphysics. Then instead of continuing to advocate the revision of the current quantum theory into a microphysics that would be compatible with Popper’s universalist-realism, Feyerabend revised his concept of realism in a manner that no longer requires the universalism that Popper demands. Generalizing on Bohr’s thesis of the relational character of quantum states when describing experimental findings with classical concepts, Feyerabend formulated his nonuniversalist, regional and historical relativist realism.
Feyerabend sets forth his statement of Popper’s universalist realist philosophy in his “Attempt at a Realistic Interpretation of Experience” in Proceedings of the Aristotelian Society (1958). This paper is an abbreviated statement of his doctoral dissertation written in 1951 at the University of Vienna. The thesis of this paper, which he calls “Thesis I”, is that the semantical interpretation of an observation language is determined by the theories that we use to explain what we observe, and that the interpretation changes as soon as those theories change. But he also states in this paper that one of the consequences of Thesis I is that we must distinguish between appearances or phenomena on the one hand and the real things appearing on the other hand. In Feyerabend’s view this distinction is fundamental to realism. On Thesis I the real things appearing are those that are referenced by the observational sentences in a certain interpretation given by a realistic explanatory theory. In both this paper and in his “Complementarity” in Proceedings of the Aristotelian Society he criticizes the complementarity thesis of Bohr’s interpretation of the modern quantum theory.
Unfortunately in all discussions of the quantum theory Feyerabend always takes Bohr’s statements and views to be authoritative and representative of the Copenhagen interpretation. In these earlier papers he acknowledges the influence of Bohm and of Popper upon his thinking. He notes that Bohr’s idea of complementarity is based partly upon empirical investigations in physics and partly upon philosophical analyses, and he accordingly distinguishes between the experimental “fact of duality” and the philosophical thesis of complementarity. The fact of duality is the result of experimental findings. Experiments displaying interference effects can be explained by wave concepts, but they contradict explanations in terms of particle concepts. Conversely experiments displaying absorption and emission can be explained by particle concepts, but they contradict explanation in terms of wave concepts.
Feyerabend therefore maintains that there is no system of physical concepts, that can explain all these experimental facts about light and matter, which is to say, there is no universal theory of light and matter. He states that for a physicist who views wave and particle as aspects of the same objective entity, the fact of duality proves that the theories available at the moment are inadequate. Such a physicist will search for a new theory and conceptual scheme, which satisfies two requirements: Firstly the new theory must be empirically adequate, and secondly it must be universal. Such a theory conforms to what Feyerabend calls the “classical ideal”, which is to say that it conforms to Thesis I, because it does not just describe appearances under certain experimental conditions, but rather it describes what light is and what matter is, the things appearing, in reality.
Feyerabend got the universalist concept of realism from Popper. In “Complementarity” (1958) he references Popper’s “The Aim of Science” published in Ratio (1957), and says it is an excellent characterization of the classical ideal of scientific explanation and its connection with realism. In this article Popper affirms that explanations in science are given in terms of universal laws of nature, which are conceived as conjectural descriptions of the structural properties of nature, that is of the world itself. He explains that by “universal” he means that scientific laws and theories must make assertions about all spatiotemporal regions of the world. Popper also speaks of different levels of universality, which he exemplifies by the greater universality of Newton’s laws relative to Kepler and Galileo’s laws. But Popper also rejects a reductionist relation between Newton and Galileo’s physics. He states that whenever a new empirical theory of higher level of universality successfully explains an older theory, it does so by correcting the older theory. He adds that the idea of independent evidence can hardly be understood without the idea of discovery, of progressing to deeper layers of explanation. Independent evidence cannot be understood without the idea that there is something to be discovered and to be discussed critically, where “deeper layers” means explanation by means of more universal laws and theories, as exemplified by Newton’s laws, which are deeper relative to Galileo or Kepler’s laws. This is the universalist-realism that Feyerabend maintained until he embraced relativism.
Feyerabend characterizes Bohr’s philosophical thesis of complementarity as the opposite of the classical ideal of scientific explanation, and he says that the difference between the classical ideal and complementarity is an instance of the age-old issue between realism and positivism. Bohr’s complementarity thesis is an instance of positivism, because Bohr maintains that the account of all evidence must be expressed in classical terms, and that it is not possible to dispense with what Bohr called the “forms of perception”. Some such as Heisenberg consider Bohr’s “forms of perception” to be neo-Kantian, and Feyerabend notes that positivists do not customarily consider phenomena to have any forms. Feyerabend therefore describes Bohr as positivist of a “higher order”. He also states that Bohr’s instrumentalist view of current quantum theory, which Bohr calls a “natural generalization of classical physics”, is merely the result of retaining classical concepts. Both the retention of classical concepts and the instrumentalist view of quantum theory are contrary to Thesis I. He therefore says that complementarity is a statement of the fact of duality and is the way in which the classical concepts appear within the predictive schemes, which replace classical laws on the atomic level. He references passages contrary to Thesis I, in which Bohr states that the difficulties of atomic theory cannot be evaded by replacing the concepts of classical physics by new nonclassical conceptual forms. At the same time while Feyerabend views complementarity to be the result of retaining classical concepts, he does not simply deny the fact of duality, or that duality will be eliminated merely by philosophical reflection with Thesis I.
With his distinction between the fact of duality on the one hand and the statement of complementarity expressing the fact of duality with classical concepts on the other hand, Feyerabend considers two approaches to a realistic microphysics. The first approach is to reinterpret the formalism of the modern quantum theory, which is a mathematical statement of the fact of duality. He admits that if the quantum theory is viewed as a predictive theory like celestial mechanics, then a realistic interpretation does not seem to be possible. But he adds that if the quantum theory is viewed as a theory containing new concepts for the description of nature, then a realistic interpretation “of a rather unusual kind” is definitely possible. This amounts to a proposal to construe the contemporary quantum theory with its duality thesis in accordance with Thesis I. Such a reinterpretation will not retain classical concepts, and will express the fact of duality without expressing complementarity. He also says that the quantum theory thus used to form new concepts about the nature of physical systems, may permit some features of the macrophysical level to be derived from quantum mechanics, and thus make duality compatible with the universality condition for realism.
As it happens in his Understanding Quantum Mechanics (1999) physicist Roland Omnès reports that recent conceptual developments using the Hilbertian framework have enabled all the features of classical physics to be derived directly from Copenhagen quantum physics. And apparently unbeknown to Feyerabend, Heisenberg had opted for this first approach, when he accepted Einstein’s thesis that the theory decides what the physicist can observe. But this first approach does not seem to have been Feyerabend’s preferred way to interpret microphysics realistically, and he says explicitly that the possibility of a realistic microphysics does not depend on supplying a realistic interpretation for the current quantum theory with its duality thesis.
His second and preferred approach is to develop an entirely new microphysical theory. This new theory would satisfy two conditions: Firstly it would be universal, and secondly it would be empirically adequate. As a universal theory it will have a unified conceptual apparatus, which when applied to the domain of validity of classical physics, will be just as comprehensive as the classical apparatus. In other words the new microphysical theory will be of a higher level of universality, such that it will also be a macrophysical theory, yet different from classical physics. Feyerabend explicitly compares the relation between the new universal microphysical physics and the classical physics, to the relation between the relativity theory of gravitation and the Newtonian theory of gravitation. The empirical adequacy criterion will be satisfied, when this realistic, universal macrophysical theory contains the current elementary quantum theory as an approximation. It may therefore contradict quantum mechanics without violating the universality criterion for realism. Feyerabend affirms that for a realist, the solution of the problem of duality need not be found in alternative interpretations of the current quantum theory, which he says is in all probability nothing but a predictive scheme anyway. Instead it can be found in the attempt to derive a completely new universal theory, which need not contain the duality thesis or complementarity. This new microphysical theory will supply new concepts for reinterpreting duality.
For ten years following these 1958 papers Feyerabend wrote a series of articles defending and advocating attempts to develop a new microphysics without duality. In these papers he contrasts his view that there can be a realistic microphysics without duality, with Bohr’s view that all future microphysics must contain the duality thesis. In “Niels Bohr’s Interpretation of the Quantum Theory” in Current Issues in the Philosophy of Science (1959) he discusses what he calls the “dogmatic elements” in Bohr’s approach. He objects that Bohr treats duality as an unalterable experimental fact that must be included in any future microphysical theory; on his Thesis I description of experiments is not unalterable. Feyerabend argues that the only condition that need be satisfied by a future microphysical theory, is that it be compatible with experimental findings to a certain degree of approximation and within a certain degree of accuracy that is required for the dogmatic elements of Bohr’s approach.
In this and other papers written during this period Feyerabend sets forth his interpretation of Bohr’s philosophy, according to which all state descriptions of quantum mechanical systems are relations between the system and measuring devices in action, that is to say, between microscopic system and macroscopic apparatus. This relational character of quantum state descriptions results from the need to restrict the application of any set of concepts to a certain experimental domain due to the wave-particle duality. Bohr’s relational view is contrasted with both the classical view and with Heisenberg’s view of measurement in quantum theory. Feyerabend says that both classical physics and Heisenberg’s view are variations on an “interactionist” view. In classical physics the interaction between the apparatus and the system can be explained in terms of the theory used to describe the system. And on Heisenberg’s view the measurement of a quantum mechanical system involves an interaction that disturbs the system in unpredictable ways.
Feyerabend says that Bohr’s relational view enabled Bohr to reply to the argument by Einstein, Podolsky and Rosen (EPR), who defended the thesis that quantum mechanical systems have definite classical states instead of indefinite states described by the indeterminacy relations. This argument postulates two systems which are separated to such an extent that no interaction can occur between them, and therefore measurement disturbance in one cannot affect the other. Bohr made his thesis of indefiniteness of state descriptions compatible with the EPR argument by assuming that states are relations between systems and devices rather than properties of the systems.
The point is that while a property of the system cannot be changed except by interaction with the measurement device, a relation can be changed without such interaction. Bohr therefore views position and momentum as relations rather than as properties of the quantum-mechanical system. Bohr attempts to express this by his distinctive use of the term “phenomenon”, which he uses to refer to the observations obtained under specific circumstances including an account of the experimental arrangement. Therefore phenomena cannot be subdivided, and dynamical variables cannot be separated from the conditions of their application. Physical attributes no longer apply to the object per se, but apply to the whole experimental arrangement with different assertions (wave or particle descriptions) appropriate in different circumstances. Bohr relativized the dynamical variables in the quantum theory to the circumstances of the experimental situation, and years later following Bohr, Feyerabend would relativize all reality to the circumstances of the knower’s situation.
But in 1962 in “Problems of Microphysics” in Frontiers of Science and Philosophy Feyerabend was still defending the possibility of a universal and therefore realistic microphysical theory without duality. He says that between 1935 and 1950 the Copenhagen interpretation had become a dogmatic “creed”, and that the objections of a few opponents such as Einstein and Schrödinger were taken less and less seriously. But he notes that more recently there has occurred the development of a counter movement, which demands that the assumptions of the Copenhagen interpretation be given up and be replaced by a different philosophy. These “revolutionaries”, as Feyerabend calls them, have shown not only that the empirical adequacy of the complementarity thesis is in doubt, but also that even empirical success is not sufficient reason to say that there can be no valid alternative to complementarity. He insists that future researchers need not and indeed should not be intimidated by the restrictions that some “high priests” of complementarity would impose.
One such revolutionary that Feyerabend has in mind is the physicist, David Bohm. Initially Bohm had accepted the Copenhagen interpretation, but later he advanced an alternative thesis in his “Quantum Theory in Terms of Hidden Variables” in Physical Review (1951), and in more detail in his books, Causality and Chance in Modern Physics (1957) and The Undivided Universe (1993). His “hidden-variable” thesis postulates the existence of a subquantum domain at a much lower and presently experimentally inaccessible (therefore hidden) order of magnitude than the quantum domain that is described by quantum theory.
In “Professor Bohm’s Philosophy of Nature”, a review of Bohm’s 1957 book in British Journal for Philosophy of Science (1961), Feyerabend says that complementarity can be interpreted in either of two ways. The way he finds acceptable is that in which it functions to provide an intuitive picture for wave mechanics, and as a “heuristic principle” guiding future research. He says that this first way is undogmatic, since it admits the possibility of alternatives including preferable alternatives, even though no satisfactory alternative exists presently. The second and unacceptable view is that of Bohr, who maintained complementarity as a basic philosophical principle incapable of refutation, and to which future microphysical theory must conform. In his review of Bohm, Feyerabend says that Bohm argues against Bohr’s dogmatic view by affirming a rôle for speculation in modern empirical physics. In a discussion of the rôle of speculation in “Problems of Microphysics” Feyerabend rejects demands by Hanson that Bohm’s theory must be set forth as an algebraically detailed and experimentally acceptable theory. He admits that such criticism is appealing to the great majority of physicists. But he maintains that such criticism puts the cart before the horse. The discussion among physicists of alternatives to the current theory plays a most important rôle in the development of physics, and a complicated physical theory cannot be invented in its full formal splendor without some preparation. Feyerabend later elaborated upon this thesis in his discussion of theoretical pluralism and counterinduction. At this stage of his thinking he advocates these ideas in order to encourage the development of a new microphysical theory not containing duality.
Norwood Russell Hanson, an academic philosopher of science, was an influential critic of Feyerabend’s philosophy of quantum physics. In an article memorializing Hanson’s death in 1967, and appearing in Boston Studies in the Philosophy of Science, Vol. III, Feyerabend says that he changed his views about the Copenhagen interpretation as a result of a series of debates with Hanson, and that by 1966 he had become persuaded of Hanson’s view. Hanson brought a different agenda to the philosophy of microphysics than did Feyerabend. Hanson was not driven to defend the possibility of a universalist-realist microphysics, but rather was attempting to explain how the quantum theory as well as other theories are discovered. More specifically he focused on the rôle of semantics of observation and of theory language in the discovery process.
Pursuit of their two agendas brought Feyerabend and Hanson into conflict. Integral to Hanson’s agenda was the belief that the duality thesis will be contained in any future microphysical theory. This belief, which Hanson held with strong conviction, was due to the personal influence of P.A.M. Dirac, the Nobel-laureate physicist who developed the field quantum theory in 1928. On the other hand Feyerabend’s agenda at that time was that a universalist-realistic microphysical theory is possible, precisely because the duality thesis need not be contained in any future microphysics, since according to Thesis I the observed fact of duality can be revised by a new microphysical theory.
Hanson’s principal statement of his philosophy of science is set forth in his Patterns of Discovery (1958). In this work he recognizes the interdependence of observation and theory in a manner similar to Feyerabend’s Thesis I, and Hanson describes observation as “theory-laden”. In the “Introduction” to his Realism, Rationalism and Scientific Method (1981) Feyerabend comments that his Thesis I is not exactly the same as Hanson’s doctrine that observation is theory-laden, because unlike Hanson, Hesse and others, he maintains that observation terms are fully theoretical and have no purely observational core. Feyerabend’s view is thus slightly different from Hanson’s thesis of “phenomenal seeing”. Nonetheless Hanson was no more sympathetic than Feyerabend to Bohr’s view that the concepts of classical physics must be used for observation in all of physics.
Hanson criticizes Feyerabend by maintaining that duality is stated by the quantum theory formalism itself, and that duality is not merely a philosophical thesis appended to the formalism, which might be replaced by an alternative interpretation not expressing duality. Hanson finds the duality thesis stated by the mathematics of the de Broglie-Einstein relations and also by the Dirac operator calculus, which enables any wave-mechanical description to be transformed into an equivalent matrix-mechanical one. Feyerabend seems not actually to have maintained the position that Hanson criticizes, even in the first of his two approaches to a realistic microphysics given in “Complementarity” (1958).
However, Hanson repeats this line of attack nearly ten years later in “Physical Implications of Quantum Physics” in The Encyclopedia of Philosophy (1967), where he characterizes Feyerabend as maintaining that the metaphysical views in the Copenhagen interpretation should be abandoned as indefensible, and that the minimal scientific content consisting of algebraic transformations and factual data is quite compatible with some interpretation markedly different from the Copenhagen one. Perhaps this is just the way in which Hanson viewed Feyerabend’s call for a new microphysics without duality, even though Feyerabend was very clear in stating that his preferred second approach is not just an alternative interpretation of the elementary quantum theory, but rather is an entirely new microphysical theory related to elementary quantum theory as Einstein’s relativity theory is to Newtonian physics.
Nonetheless, the thrust of Feyerabend’s attack is against Bohr’s thesis that classical concepts in the complementarity description of the fact of duality must occur in microphysics including any future microphysics. In “Comments on Feyerabend’s ‘Niels Bohr’s Interpretation of the Quantum Theory’...” (1959) Hanson sets forth what he considers to be the minimal essentials of the Copenhagen interpretation: Firstly he maintains that past and present microphysical experience make it probable but in no sense necessary, that any future microphysical theory will incorporate the quantum postulate and the duality principle. Secondly he notes that there presently exists no coherent, currently workable and fully articulated conception of a microphysical theory, which can do without the quantum postulate and the duality principle. He maintains that Feyerabend is correct to score the strident statements of Bohr and Rosenfeld, when they violate the history of physics by suggesting that any future microphysics will of necessity guarantee things like complementarity.
But Hanson adds that Bohr’s metaphysics is not an indispensable part of the Copenhagen interpretation, and he therefore distinguishes the “Copenhagen interpretation” from the “Bohr interpretation”. He states that if the Bohr interpretation is “cut away”, then what remains is a “liberalized Copenhagen interpretation”, which is entirely defensible. And he maintains that there are good contingent arguments in support of the expectation that any future microphysics will incorporate the quantum postulate and the duality principle, and emphasizes that presently there exists no working alternative to the current quantum theory notwithstanding all its awkward features. But Feyerabend’s response to Hanson’s criticisms did not result in a “liberalized Copenhagen interpretation”. What Feyerabend produced is an elevation of the Bohr interpretation to a generalized and quite radical relativistic philosophy of knowledge. It seems unlikely that Feyerabend understood what Hanson wanted to “cut away”.