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BOOK IV - Page 6
 

WERNER HEISENBERG AND THE SEMANTICS OF QUANTUM MECHANICS

 
   

            A second comment about mathematics in physics is that in the empirical sciences equations and inequalities express universal logical quantifica­tion, which is changed to particular logical quantification when any of their constituent variables are given numerical values by measurement, or by calculation with the equation whose initial conditions have been satisfied by measurement.  Each measurement performance is an individual measurement instance, which is not the same as an individual entity.  Differ­ent measurement performances will likely result in dif­ferent measurement values, either due to measurement errors in the execution of the measurement procedures described in the statements of an experimental design, or due to different initial conditions in the ranges of the variables.  An equation is not given particular logical quantification merely by associated inequalities expressing limits on the range of possible values of its variables, as in the indeterminacy relations in quantum theory.  Such conditions may severely restrict the range of applicable values.  But there is always a universal claim made by the equation, because there are an indefinitely large number of possible measurement performances in repeatable experiments.  Also equations are not given particular quantification, when only their parameters such as constant coefficients are given specific values.  Furthermore no mathematically expressed theory need be a more "general theory" relative to any other theory, in order to be a logically universal statement.  In the case of quantum physics the microphysical quantum theory need not also be a macrophysical theory, in order to be a universal theory, just as it need not be a biological or a sociological theory, in order to be a logically uni­versal expression.  Logical reductionism is not a condition for logical universality.  Therefore equations can express universality like substantive statements in logic, and they may be included in semantical description lists to add to the semantics of a meaning complex associated with a term and to reduce the meaning’s vagueness, if the term is a mathematical variable.
          To summarize this alternative to the wholistic view: the meanings associated with descriptive terms are not simple wholes, but are complexes having component parts, which in turn are meaning complexes associated with other descriptive terms to which the former are related in universal affirmations believed to be true.  The composite meaning complex is exhibited in a semantical description, which consists of a list of one or several universal affirmations having a common subject term with its component parts exhibited as predicates.  The universal affirmations may also include mathematical expressions with descriptive terms appearing as variables.  Vagueness is a property of concepts, and exists to the extent that descriptive terms cannot be related to one another in universal statements believed to be true.  Vagueness limits the size of a semantical description list, and thus also limits the propagation of semantical change through the web of beliefs.
          Consider next the relation between the language of observation and the language of theory, the second basic assumption in the doctrine of closed-off theories.  The word "theory" is still used conventionally to refer to Newton's "theory" of gravita­tion, to Einstein's "theory" of relativity, and to the quantum "theory", even though the physics profession had decided many years ago either to accept or to reject these expressions as physical explanations.  In this conventional usage the term "theory" does not have the same meaning as it did when these expressions were firstly advanced for testing as proposed explanations of problematic phenomena.  When they were firstly proposed, these expressions represented statements that had a much more hypothetical status in the judgment of the profession than they do today, and they were typically topics of controversy.  There is, therefore, an ambiguity between "theory" understood as an accepted or rejected explanation, and "theory" understood as a tentative proposal submitted for empirical testing.  Unlike the former archival understanding, which Hanson calls "almanac" science, the latter Pragmatist understanding of "theory", which Hanson calls “research science”, pertains to the function of language at the frontier of the development of a science, where the function under considera­tion is empirical testing.  Only this latter understanding is strategic in the Pragmatist philosophy of science, even though the former meaning and still conventional usage may occur in its expository discourse.  From this functional or Pragmatist view theories may be defined as universal statements that are proposed for testing, and explanations are former theories that have been tested and not falsified.  Theory that is tested and not falsified by a competent test ceases to be a theory and is given the status of an explanation, even though there may be other tested and nonfalsified former theories addressing the same problem also having the status of explanations accepted by some scientists in the same profession.  Some scientists are uncomfortable with this pluralism, but the contemporary Pragmatist philosophers recognize such pluralism as historically characteristic of science.
          In an empirical test the semantics of the vocabulary in all the relevant discourse is controlled by a strategic decision that is antecedent to the performance of the test.  This is the decision as to what statements are presumed for testing and what statements are proposed for testing.  The former lan­guage is the explicit statements of test design together with usually many tacit assumptions, and the latter is the explicit statements of the theory.  This decision is entirely pragmatic, since it is not based on the syntactical or the semantical characteristics of language, but rather is based on the use or function of the language, namely empirical testing.  The test design statements are those that by prior decision and agreement among cognizant members of the profession have the status of definitions.  These statements are presumed to be true regardless of the outcome of the test, and serve to identify the subject of investigation through­out the test.  The theory is the language that by prior decision and agreement among the cognizant members of the profession has the less certain status of a hypothesis.  The hypothesis is believed to be true to the extent that it is considered worthy of testing, although the proponent and his entourage of cheering advocates may be quite firmly convinced.  But if the test outcome is a falsification, then it is the statements of theory and not the statements of test design, that are judged to have been falsified.  However, a falsifi­cation may lead some interested scientists, such as the theory's proponent and advocates, to reconsider the beliefs underlying the test design, even while admitting that the test was executed in accordance with its design.  This role reversal between test design and theory may result in productive research.  When the falsified theory is made a test design statement characterizing the problematic phenomenon, the problem has become reconceptualized.  As Conant discovered to his dismay, the history of science is replete with such prejudicial responses to scientific evidence that have been productive and strategic to the advancement of basic science in historically important episodes.
          The decision distinguishing test design and theory language made prior to the experiment may but need not result in identifying mathematical equations as the state­ments of theory and of identifying colloquial discourse or substantive language as the statements of test design.  The decision is not based on syntactical characteristics of the language, and the test design statements often include mathe­matically expressed statements together with statements in substantive language describing the measured phenomenon, the measurement procedures, and the design and operation of the measurement apparatus.  Even more relevantly the decision is not based on semantical criteria, as advocates of the naturalistic philosophy of the semantics of language believe.  The decision is not based on any purportedly in­herent distinction between observation and theory, whether or not, as in the case of quantum theory, the observation concepts are called "classical" or "macroscopic", and the theoretical concepts are called "quantum" or "microscopic".  The distinction between statements of test design and statements of theory is neither syntactical nor semantical; it is distinctively and entirely pragmatic.
          Consider the language of an empirical test before the test is executed.  In order for the test design statements to characterize evidence independently of the theory proposed for testing, the test design statements and the theory state­ments must be logically independent.  Neither set of statements may be merely a transformation of the other, and the test design statements may neither deductively imply nor contradict the theory or any of its alternatives.  Furthermore the statements of the theory are too hypothetical to function as definitions, except per­haps for the proponent and other advocates of the theory, who may believe in the theory as strongly as they believe in the truth of the test design statements.  But for all those critical researchers for whom the test is a decision procedure, the semantical consequence of the logical independence and hypothetical status of a theory relative to the universal statements of test design, is that each of the terms common to both the test design statements and theory statements have their semantics defined in relation to the meanings of the other terms in the test design state­ments, such that they characterize the subject matter of the experiment, but not defined in relation to the meanings of the other terms of the theory.  In other words the theory statements are not included in the same semantical description list as the test design statements, even though both sets of statements are mutually consistent and contain the same common subject term.  The meaning of each term common to the test design and theory statements is therefore vague with respect to the meanings of the other terms of the theory.  And on the artifactual thesis of the semantics of language the observation language in turn is merely the test design statements with their logical quantification changed from universal to particular, to enable their use to describe the particular ongoing or historical experiment performance.  The test design statements similarly supply the vocabulary that describes the observed test outcome, even if the outcome contradicts the claims of the tested theory, thus falsifying the theory.
          Consider next the language of the empirical test after the test is executed.  When the test is executed, a falsifying test outcome produces no semantical change except for the proponents and advocates of the theory, who had been convinced of the theory’s truth, and then choose to reconsider their belief in the theory due to the test outcome.  But a nonfalsifying outcome produces a semantical change, especially for the critics of the theory for whom the test is a decision procedure.  After the test the theory no longer has the hypothetical status that it formerly had merely as a proposal, but assumes the status of an explanation, which is neither more nor less contingent than other accepted universal empirical statements includ­ing the test design statements.  The semantical outcome is that both the test design statements and the theory state­ments (now elevated to the status of an explanation) are semantical rules exhibiting the composition of the meanings of the univocal terms common to both sets of statements.  Those component parts defined by the test design statements remain unchanged.  But the semantical descriptions for these terms now include not only the test design statements but also the statements constituting the tested and nonfalsified theory.  These theory statements are additional information learned from the test outcome that resolves some of the vagueness in the vocabulary terms common to both the theory and the test design statements.  In summary: the descriptive terms common to both test design and theory statements have part of their semantics defined by the test design statements throughout the test, both before, during, and after the test is executed.  And these common terms have part of their semantics augmented and thus defined by the statements of the tested and nonfalsified theory added after the test. 
          In Heisenberg's doctrine of closed-off theories the naturalistic philosophy of language requires retention of the Newtonian concepts for observation in the context of the quantum theory.  But the resulting equivocation is unnecessary, if it is remembered that the Newtonian concepts are never involved, since the Newtonian theory is a falsified microphysical theory.  It is sufficient to use a less precise vocabulary that Heisenberg calls "everyday" words used by physicists in order to describe the experimental set up, which is a macro­physical phenomenon.  The meanings of these everyday concepts are vague about the fundamental constitution of matter.   After the quantum theory was recognized as exper­imentally adequate, the vagueness in these everyday concepts was resolved by the equations constituting the statements of the quantum theory, because the quantum theory is the tested and nonfalsified theory, which after the test became a semantical rule contributing meaning parts to the complex meanings of these univocal terms.  For this resolution of vagueness to occur it is not necessary for the Newtonian macrophysical laws to be made logical extensions of the quantum theory by logical reduction procedures, because the Newtonian theory is falsified as a microphysical theory.  Nor is it necessary for the Newtonian macrophysical laws to be replaced by a macrophysical theory that is an extension of the quantum laws.  The univocal semantical thesis neither implies nor requires Hugh Everett's "many worlds" interpretation (which furthermore is in principle empirically untestable), nor does it imply or require any other reduc­tionist development of a macrophysical quantum theory, i.e. a macrophysical theory which is deductively or reductively a logical extension of the microphysical quantum theory.  It is sufficient merely that the scientist realize that the nonfalsifying test outcome has made the quantum theory and not classical physics an empirically warranted micro­physical theory.
          Heisenberg's doctrine of closed-off theories is incorrect, and Einstein's semantical thesis expressed in his admonition to Heisenberg is correct, because the vocabulary used for observation after the quantum theory's acceptance is a univocal vocabulary with meaning parts from the quantum theory.  The descriptive terms in the equations of the quantum theory contribute to, and thereby resolve some of the vagueness in, the meaning complex associated with the descriptive terms used for observation.  Thus the quantum theory decides what the scientist observes in the Wilson cloud chamber.  The macrophysical description is not in contradiction to the microphysical quantum theory including the indeterminacy relations.  The quantum concepts are included in the univocal meaning complexes associated with the observation description.  The Newtonian concepts were never included, because the macrophysical description never affirmed a Newtonian microphysical theory.
          In his "Remarks on the Origin of the Relations of Uncertainty" in a memorial volume dedicated to him titled The Uncertainty Principle and Foundations of Quantum Mecha­nics (1977), which was in press at the time of his death in 1976, Heisenberg concludes the brief four-page article by saying that there have been attempts to replace the tradi­tional language with its classical concepts by a new lang­uage which should be better adapted to the mathematical for­malism of quantum theory.  But he adds that during the preceding fifty years, physicists have preferred to use the traditional language in describing their experiments with the precaution that the limitations given by the uncertainty relations should "always be kept in mind". He concludes that a "more pre­cise" language has not been developed and in fact it is not needed, since there seems to be general agreement about the conclusions and predictions drawn from any given experiment in the field.          Regrettably Heisenberg never repudiated his doctrine of closed-off theories.  But contrary to his doctrine of closed-off theories, Heisenberg’s statement that the contemporary physicist must keep quantum effects "in mind" when the physicist is describing macrophysical objects, even while not explicitly accounting for quantum effects that are experimentally undetectable in the circumstances, is prima facie evidence of a semantical change in the univocal macrophysical vocabulary used to describe experiments due to the development of quantum theory.  In other words a “more precise” language with a less vague semantics has in fact evolved.  This semantical evolution consists in the fact that the concepts employed for description contain component parts from the quantum theory.  That is how the limitations of the uncertainty relations are “always kept in mind”: they have become built into the semantics of those terms, even when those terms are used to describe observations.
          Heisenberg’s semantical theory of equivocation is the result of the acceptance of the naturalistic philosophy of the semantics of language together with the assumption that meanings are simple, indivisible wholes. However, all such views are untenable, because they imply what can only be called "double think".  The equivocation thesis demands that the modern physicist indulge in a contrived cognitive dupli­city with himself, a pretext of simultaneously both knowing and not knowing the modern quantum theory.  But con­cepts are not known like physical objects to which one may simply close one’s eyes; they are knowledge.  Scientists never did in practice carry on the kind of cognitive duplicity that the equivocation semantical theses require, and since the ascendancy of the contemporary Pragmatism, philosophers no longer expect that they should.  Heisenberg might have obtained greater utility from his insightful idea of “everyday” concepts, had he rejected Bohr’s philosophy of observation language, and realized that neither these everyday concepts nor the Newtonian concepts nor any other concepts are inherently observational.  In the Pragmatist perspective “everyday” concepts are distinctive only because they are vague in a very strategic fashion: they are the concepts used in test design statements, and are vague relative to the concepts in the theories proposed for testing prior to execution of the test and prior to the production of a nonfalsifying test outcome.  In the case of the quantum theory experiments, everyday concepts are vague because they are not defined by the axiomatic systems of either the Newtonian or the quantum theories or of any other proposed microphysical theory prior to the execution of the tests.
          In “On the Methods of Theoretical Physics” in Ideas and Opinions (1933) Einstein said that if you want to find out anything from the theoretical physicists about the methods they use, stick closely to one principle: don’t listen to their words, but rather fix your attention on their deeds.  This might be construed as good advice for anyone attempting to understand Heisenberg’s philosophy of science.  The philosophy of science that Heisenberg practiced as a result of Einstein's influence and chronicled in his autobiographical works, is historically more important than the one he expounded as a result of Bohr's influence and set forth as his doctrine of closed-off theories.  In the philosophy he practiced, he anticipated the contemporary Pragmatist philosophy of science by at least a quarter of a century.  Because contemporary Pragmatism is based on an artifactual view of the semantics of language, it implies the interdependence of belief and semantics.   On the naturalistic view of seman­tics, the truth of empirical statements is dependent on meanings which in turn are determined independently by the natural processes of perception which are thought to capture some presumed or preferred ontology.  On the artifactual view truth and meaning are mutually determining in empirical statements believed to be true.  Thus on the artifactual thesis, when Heisenberg used Einstein's admonition for developing the uncertainty relations, he had made a prior commitment to the empirical truth of the equations expressing them, and he then used their concepts for his theory-dependent observation of the Wilson cloud chamber tracks made by the free electron.  Years later Feyerabend will call this counterinduction even though he seems never to have recognized its occurrence in Heisenberg's practice.  Had he done so, he might have spoken of the Galileo-Einstein-Heisenberg tradition, and produced a philosophy of quantum theory different from than his relativist philosophy.
Furthermore, given the Pragmatist thesis of scientific realism, the thesis that empirically warranted discourse has a semantics describing an ontology, the artifactual philosophy of the semantics of language implies the mutual determination of truth and ontological claims.  In scientific realism, however, the truth is the empirical warrant earned by testing with no falsification.  Heisenberg too practiced this, when unlike Bohr, he reported that he construed the quantum mechanics realistically when he imitated Einstein’s realism.  He said the decisive step in the develop­ment of special relativity was Einstein's rejection of the distinction between apparent time and actual time in the interpretation of the Lorentz transformation equa­tion, and his taking Lorentz’s apparent time to be physically real time while rejecting the Newtonian absolute time as real time.  He said he took the same kind of decisive step, when he inverted the question of how to pass from an experimentally given situation to its mathematical represen­tation, by affirming that only those states represented as vectors in Hilbert space can occur in nature and be realized experimentally. This is not a positivist claim about mere phenomenal appearances; it is an ontological claim backed by the theory’s empirical warrant as tested and not falsified. Unlike Bohm’s hidden variable ontology Heisenberg’s realist step did not involve creating “interpretations” by supplementing the quantum theory with additional characterizations that are not affirmed by the tested and nonfalsified theory.  Nor is it like Bohm’s informal characterizations that are separable from the quantum theory, and which enable no new empirical tests or new predictions, and therefore offer no empirically warranted ontological claims.
          Similarly for the potentia ontology, if contrary to Heisenberg potentia is taken to refer merely to the fact that position and momentum measurement instances cannot both occur simultaneously, such that they may be taken realistically as a manifestation of reality - rather than supplementary claims about entities, which cannot even be referenced in mathematical measurement language. Initially the quantum theory’s stark and spartan realism was strange, and “wave” was a metaphor.  But metaphor is new and unconventional meaning that convention converts to dead metaphor, i.e. new literal meaning.  Contemporary realists can let the theory and experiments change the old literal meanings to new literal meanings, as continuing experimental research will further enrich the theory’s descriptive semantics and ontology.  Today’s pragmatic scientific realism is the thesis that a theory’s ontology - its view of reality - is described by the semantics of language that is defined by the context of universal discourse accepted as empirically true. This language characterizing manifestations of mind-independent reality includes the empirically tested and nonfalsified theory, all its associated test-design language needed for measurement and/or other observation, and descriptions of additionally related experimental findings. Unlike both the Bohm and the Bohr interpretations this language characterizing manifestations of reality neither affirms nor denies supplemental ontological claims that lack of warranting empirical evidence.    
      Heisenberg’s practice of scientific realism anticipates Quine’s doctrine of ontological rela­tivity and also Quine’s rejection of all first philosophy, namely the use of prior ontological commitments such as Einstein's commitment to determinism as criteria for scientific criticism.  Contemporary Pragmatists like Quine reject ontological criteria in scientific criticism.  They admit only empirical criteria for scientific criticism, and let the statement of the empirically tested and nonfalsified theory describe both the semantics and the ontology of the theory's domain.


 

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