BOOK VII - Page 5

Hanson on Perception, Observation and Theory

Hanson defends the Copenhagen interpretation, and criticizes the hidden-variable interpretation and Bohm’s agenda.  He maintains that in microphysics all the limitations placed on our conceptions of what the microphysical world is like and what we can observe, are really limitations arising out of the linguistic features of the formal languages available.  This is also Benjamin Lee Whorf’s thesis of linguistic relativity written twenty years earlier.  Such is particularly the case with Heisenberg’s indeterminacy relations. 

The indeterminacy relations and Heisenberg’s thought experiment involving a gamma-ray microscope are often said to state limits to the possibility of observation within microphysics.  Hanson says that this is true in an unsuspecting way: there never have been nor could there ever be experiments or observations pertinent to the establishment of the indeterminacy relations, because these relations are the conceptual or logical consequence of the language of quantum theory.  In the formalisms for modern quantum physics there is a logicolinguistic obstacle to any attempt to describe with precision the total state of an elementary particle, and if there is a conceptual limit to such a description, then there is ipso facto a limit to such observation.  The conceptually impossible is the observationally impossible.   Hanson’s thesis is that theory is integral to observation or, as he also says, observation is “theory-laden”.  This is also Einstein’s aphorism to Heisenberg that it is the theory that decides what the physicist can observe.  Hanson’s is the same philosophy of observation that Einstein told Heisenberg in 1925, and that Heisenberg used to develop the indeterminacy relations. 

But Hanson was not led to develop his philosophy of observation by reflection on Whorf’s 1942 paper “Language, Mind and Reality” or on Heisenberg’s autobiographical chronicles, in which Heisenberg relates his discussion with Einstein and the use that he made of it.  In fact Hanson identified Heisenberg’s views on observation with those of Bohr, which Heisenberg included in his explicit and systematic philosophy of closed-off theories.  Nor was Hanson led to develop his philosophy in response to Feyerabend’s criticisms of Bohr’s dogmatic interpretation of quantum theory; Hanson’s philosophy of observation was developed many years previously.  His philosophy of observation was drawn from Wittgenstein’s Investigations and from gestalt psychology. 

Therefore consider briefly Wittgenstein’s ordinary-language philosophy and Hanson’s use of it in his philosophy of science.  Ludwig Wittgenstein (1889-1951) was a somewhat reclusive individual who wrote a somewhat unsystematic philosophy of language in a somewhat obscure style, and who is thought to have anticipated certain ascendant trends in philosophical thinking.  In fact Wittgenstein seems twice in his lifetime to have anticipated successfully an ascendant trend in philosophical thought with his two principal works: firstly his Tractatus Logicus-Philosophicus (1922) and then later his Philosophical Investigations (1953).  The thesis of the latter explicitly includes a repudiation of the thesis of the former, yet each work gathered its own retinue of sympathetic interpreters and devout disciples.  Both the Tractatus and its author attracted the attention of Schlick and his Vienna Circle (with the noteworthy exception of Carnap, who after his one and only meeting with Wittgenstein was unforgettably unimpressed).  But in spite of Schlick’s invitations to join the Vienna Circle, Wittgenstein remained aloof from them, just as he remained aloof from all other sublunar states of human affairs. 

About thirty years later Wittgenstein’s Investigations inspired philosophers who were becoming disillusioned with the technical pedantics of logical positivism, and its thesis occasioned the formation of a new philosophy of language.  Conventionally historians of philosophy now refer to the two opposing dogmas in these two books as the ideal-language tradition and the ordinary-language tradition respectively.  The ideal-language view set forth in the Tractatus has a reformist aspect, which accorded special status to symbolic logic, such as may be found in Russell’s Principia Mathematica.  The Tractatus advanced an interpretation for symbolic logic, consisting of what is called the “picture-theory” semantics.  This is one of many variations on the naturalistic theory of the semantics of language, and it is also the most naïve.

This first book also advanced a constructionalist view of language.  It described all sentences in the ideal language as consisting of elementary sentences, which in turn consist of semantically independent names of simple objects.  All nonelementary sentences are compound sentences constructable from the elementary ones.  The former is said to be truth functional, which means that the truth of the constructed compound sentences depends completely on that of their component elementary sentences.  As a result of this semantical atomism and logical constructionalism, the understanding of any sentence ultimately reduces to knowing what its constituent names reference and its logical structure.  This is a variation on the mechanistic philosophy of the semantics of language, and was called “logical atomism”. 

The principal argument in defense of the ideal-language tradition is that ordinary language is unsuitably vague and too ambiguous for philosophy, just as ordinary language is unsuitable for the empirical sciences like modern physics, which rely on mathematics.  The initial attractiveness of symbolic logic to philosophers of science was the expectation that it could serve philosophy as mathematics serves physics.  This programme evolved into the logical positivist reductionist programme advocated by Carnap and others such as Feigl and Hempel, in which the controlling agenda is the logical reduction of theories to a semantically significant (i.e., meaningful) observation language, in order to demonstrate the semantical meaningfulness of scientific theories, which are otherwise presumed to be meaningless.

But experience with the reformist efforts of the ideal-language philosophers, notably the logical positivists, led some younger philosophers to charge that ideal languages are even more unsuitable than ordinary language for philosophy, and that philosophical analysis should be directed toward the examination of colloquial discourse.  The outcome was a new folk philosophy that is self-consciously naïve.  Wittgenstein anticipated this reaction, perhaps because it was also his own reaction to his Tractatus. He was then led to develop his ordinary-language philosophy.   Early statements of his new philosophy were set down in a set of notebooks later published as The Blue and Brown Books (1958), and the more mature statement is the Investigations (1953). 

The latter work describes philosophy as a kind of empirical linguistics, and its main emphases are (1) the variety of uses of language, (2) the need for the philosopher to consider statements not in isolation but in the circumstances that occasion their utterances, and (3) the definition of meaning in relation to usage.  Wittgenstein maintained that the problems of philosophy originate in philosophers’ misunderstanding of certain crucial terms such as “know”, “see”, “free”, “true”, “reason”, and that the resolution of these problems requires examination of the uses of these words as they occur in ordinary-language discourse. 

The later Wittgenstein seems clearly to have rejected the naturalistic theory of the semantics of language.  He says rhetorically in the Investigations that if the formation of concepts can be explained by facts of nature, then the philosopher should not be interested in grammar, but rather in what in nature is the basis of grammar.  He affirms that the philosopher is not interested in natural science or in natural history, and that an artifactual theory of the semantics of language implies that a concept is comparable to a style of painting.  But the artifactual theory that he accepts seems to be a wholistic one, since he states in the opening pages of The Blue and Brown Books that understanding a sentence means understanding a whole language.

Hanson was of the generation of philosophers who took their professional education after the Second World War, and he was also one of those who looked to Wittgenstein’s new philosophy to rise above the inadequacies of the prewar logical positivist philosophy of science.  But he was not an ordinary ordinary-language philosopher.  He was firstly a philosopher of science, and if there was an ordinary language of interest to him, it was the language ordinary to contemporary physics including most notably microphysics.  He was specifically drawn to Wittgenstein’s comments in the Investigations about seeing, in order to re-approach the subject of observation in physics, which quantum theory had made so problematic. 

Hanson’s discussions about observation and theory are set forth in Patterns of Discovery, in “Observation and Interpretation” in Philosophy of Science Today (1967), and in Perception and Discovery.  He rejected the positivist view that seeing is merely a matter of predetermined sensations, sense data, phenomena, or retinal reactions in the eye, and that interpretation is something added to the predetermined perception as a secondary and discrete step in the perceptual process.  Instead he says “there is more to seeing than meets the eye”, and he follows Wittgenstein’s view that interpretation is an integral component of seeing instead of something imposed upon it.  The significance of this point is that perception is not predetermined and fixed by nature but is variable, and he illustrates this variability in perception by using both Wittgenstein’s and others’ ambiguous drawings that admit to reversible optical interpretations.  He explicitly invokes gestalt psychology (something that Wittgenstein did not do), to explain the reversibility of interpretations of ambiguous drawings as changes in the conceptual organization of what is observed. 

In this context Hanson references Duhem’s example in The Aim and Structure of Physical Theory of the layman visiting a physicist’s laboratory.  The layman would have to learn physical theory before he could observe what the trained physicist observes.  Duhem had described this commonplace state of affairs in terms of his positivist semantics of observation and theory.  But Hanson is a critic of positivism, and does not maintain any such two-tiered semantical thesis, as had Duhem.  Hanson maintains that Duhem’s postulated laboratory situation reveals that the elements of the laboratory in the visitor’s field of perception are not organized as they are for the trained physicist.  Physical theory provides the physicist with patterns within which data appear intelligible; it is what makes possible observation of phenomena as being of a certain kind and as related to other phenomena.

To illustrate his thesis that perception is theory-laden, Hanson uses the example of the second-century and the seventeenth-century astronomers who both look at the dawn.  They both have the visual experience of the rising sun, but they do not see the same thing, because each believes different astronomical theories: the former, Ptolemy, believes in the geocentric theory, the latter, Galileo, in the heliocentric theory.  Nevertheless, it can still be said that they see the same thing, since the sun could be described by both as a brilliant yellow disk.  Hanson calls this latter kind of description “phenomenal seeing”, but he maintains contrary to the positivists that such phenomenal seeing is not the ordinary way of seeing.  It is something that requires special effort, because seeing is normally interpretative, and is used when the observer is confronted with a new seeing experience, in which case what is seen cannot be characterized by reference to his background knowledge.  Observation in science aims to pass beyond the phenomenal seeing occurring in the case of the new experience, and to get the visual experience to cohere against a background of accepted knowledge.

The differences between gestalts are due to differences in previously acquired background knowledge, knowledge that involves language. Hanson was therefore led to follow Wittgenstein’s ordinary-language analysis, because examination of commonly used locutions in colloquial discourse reveals the relation between language and the variability of interpretation in observation.  The locution “seeing as” reveals that seeing is to see an object as a certain kind of thing, which is brought out by the verbal context in which the locution occurs.  The text in its context supplies the interpretation.  But his thesis is still stronger than merely stating that language reveals an interpreting conceptual component; he invokes the locution “seeing that” to exhibit a necessary rôle for language in interpretation. 

The idea of “seeing that” explains the relation of “seeing as” and the observer’s background knowledge: to see something as a certain kind of thing is “to see that” it behaves in a certain known and expected manner.  The “seeing that” locution supplies a statement of the background knowledge, which can be true or false.  Seeing is therefore a theory-laden activity in the sense that the seeing is interpreted by reference to our background knowledge.  Without a linguistic component to seeing, nothing we saw could be relevant to our knowledge.  Before the wheels of knowledge can turn relative to a given visual experience, some assertive or propositional aspect of the experience must have been advanced.  Only statements can be true or false; visual experiences must be cast into the form of a language to be considered in terms of what we know to be true, i.e., in terms of our theories.

Furthermore, Hanson’s thesis is not only that language is necessary for the interpretation that is integral to perception, but also that the logicogrammatical form of the language used for description exercises a formative control over the interpretative thinking that occurs in perceiving.  Just as seeing may be stated locutions, which are “that...” clauses, so too can facts and theories.  For this reason Hanson claims that in the second century Ptolemy could not express what were facts for Galileo fifteen centuries later.  Physical concepts are intimately connected with the formalisms and notations in which scientists express them, including the formalisms used today in contemporary microphysics. 

The dependence of physical concepts on the mathematical formalisms is a very strategic consideration in Hanson’s rejection of attempts by Bohm and Feyerabend to propose interpretations of the Heisenberg indeterminacy relations and the Schrödinger wave function that are alternatives to the Copenhagen interpretation of quantum theory.  For Hanson the Copenhagen interpretation is precisely that interpretation which is supplied by the formalism of the quantum theory, because contrary to both the positivists and to Bohr, it is the formalism that supplies the intelligible patterns and conceptual organization in perception for the observations relevant to microphysics.  Interestingly in his Primer of Quantum Mechanics (1992) Chester Martin explicitly exhibits Dirac’s mathematical notational system for quantum theory as a language, and references the linguistic philosophy of Whorf.  Whorf’s thesis of linguistic relativity is similar to Hanson’s view.

Hanson further follows Wittgenstein when he maintains that the meaning of a sentence is its use, and that there are multiple uses for a sentence.  Thus he states that the laws and theories of physics have many uses, and not just one, as most philosophers have maintained.  The contingently empirical status of a statement is one of the uses of the theory in science.  Another is to make the phenomena cohere in an intelligible way, such that empirical disconfirmation does not result in the negation of the concept described by the theory, but rather results in no coherent concept at all.  The dynamical laws of classical physics, for example, are a system of fundamental propositions that are empirically true.  But these fundamental propositions are treated as axioms, such that the system delimits and defines its subject matter.  Then nothing describable within the system could refute its law statements; disconfirmatory evidence counts against the system as a whole, and only shows that the system does not apply, where formerly it was thought to apply.  Hanson calls this use of laws and theories “functionally a priori”. 

The idea of the functionally a priori is suggestive of Heisenberg’s comments in “Questions of Principle in Modern Physics”, in which he says that it is not the validity but only the applicability of classical laws, which is restricted by modern relativity and quantum physics.  Hanson does not reference Heisenberg, but his thesis of the functionally a priori use of laws and theories is in this respect similar to Heisenberg’s doctrine of closed-off theories, with the noteworthy exception that Hanson does not reserve certain axiomatic systems such as classical mechanics for observation in physics, as does Heisenberg in his explicit philosophy of physics.  Heisenberg’s philosophy of observation in his doctrine of closed-off theories does not admit the variability in perception that Hanson’s philosophy asserts.  Instead in his explicit philosophy Heisenberg followed Bohr’s thesis that there are “forms of perception” that are found only in colloquial language and in its refinements in classical physics.

Hanson’s semantical investigations occasionally took a turn away from the wholistic approach of gestalt psychology.  In the chapter on classical particle physics in Patterns of Discovery he considers the idea that the meanings of some terms have their properties built into them, such that falsification of statements predicating those properties of the described substances is effectively impossible.  And in “Newton’s First Law: A Philosopher’s Door into Natural Philoso­phy” in Beyond the Edge of Certainty (1965), he states that rectilinearity, motion ad infinitum and free force, are conceptions within classical mechanics that are interdependent, in such a way that it is possible to treat the idea of uniform rectilinear motion ad infinitum as itself built into the notion of free force and as part of the latter’s semantical content.  The terms in Newton’s first law are semantically linked: the meaning of some of its component terms “unpacks” sometimes from one or two of the others, but then sometimes the meanings of these unpack from that of the first.  Unlike gestalt psychology this is a version of componential semantics.  Which are the contained and which are the semantical containers can affect the logical exposition of any mechanical theory built thereon.  These are semantical decisions which determine that in different formalizations of Newton’s theory different meaning relations will hold between the law’s constituent terms. 

The term “unpack” in connection with semantical analysis is a phrase used by the early pragmatist philosopher William James, although Hanson does not reference James.  It is unclear whether or not Hanson ever thought of this type of semantical analysis as an alternative to his frequent recourse to gestalt psychology.  Nevertheless it is an alternative componential-semantics approach in semantical analysis, because it is not wholistic.  On the gestalt thesis it is not possible to unpack a gestalt into its component parts, because the gestalt is more than a mechanical organization of its parts.  The gestalt describes the synthetic psychological experience of perception; it is not a linguistic semantical analysis.  In his discussions of observation in quantum theory Hanson never exploited this mechanistic or logical analysis of meanings into component parts.

Hanson’s Philosophy of Science 

Aim of Science and Scientific Discovery

Hanson’s ideas about the aim of science pertain to what he calls “research science”, as opposed to what he calls “catalogue-sciences”, which are ideas that are integral to his views on scientific discovery.  In his “Introduction” in Patterns of Discovery he states that in a growing research discipline, inquiry is directed not to rearranging old facts and explanations into more elegant formal patterns, but rather to the discovery of new patterns of explanation.

The idea that observation is theory-laden is strategic to this purpose.  In the chapter titled “Observation” in Patterns of Discovery he states that the scientist aims to get his observations to cohere against a background of established knowledge.  This kind of seeing is the goal of observation.  And similarly in the last chapter titled “Elementary Particle Physics”, the area of contemporary physics that he says is presently a research science, he states that intelligibility is the goal of physics, by which he means the conceptual struggle to fit each new observation of phenomena into a pattern of explanation.  Often the pattern precedes recognition of the phenomena, as Dirac’s theory of 1928 had preceded discovery of the positron.  But then Dirac’s pattern was itself the outcome of an effort to find a suitable explanation for prior phenomena, namely a unified, relativistically invariant theory of electron spin, which would give the correct fine-structure formula, explain the Zeeman effect of doublet atoms, describe the Compton scattering of X-rays, and supply a model of the hydrogen atom.

Scientific Explanation

Hanson offers an evolutionary perspective on scientific explanation.  In the third chapter of Concept of the Positron he states that the concept of scientific explanation has experienced an historical evolution that follows upon the historical development of physics.  Leibniz had denied that Newton’s theory offers explanation, even though he admitted that it offers acceptable predictions.  Today the concept of explanation advanced by the positivists, such as Hempel, is based on the concepts of Newton’s physics including notably the deterministic thesis that explanation implies deterministic prediction.  The concept of explanation implied in the nondeterministic quantum theory was slow to get accepted. 

Hanson states that if just after Le Verrier had predicted the existence of the planet Neptune in 1847, a time when Newtonian physics had reached its apex, some physicist had proposed a new theory that explained all that Newton’s theory explained and furthermore explained several minor flaws in Newton’s theory, then the new and better theory would have been viewed as merely a predictive device and not an explanation. But if Newton’s theory then began to show major weaknesses, while the new theory succeeded where Newton’s had failed, still these accomplishments would decide nothing.  The scientists would begin to show increasing reliance on the new theory, yet it would not be accepted as an explanation.  All the same, younger physicists would develop the new theory further.  Finally if Newton’s physics had begun to fall apart while the new theory opened up new branches of science, focused on problems never before perceived, fused disciplines previously thought to be distinct, and sharpened experimental techniques to an unprecedented degree, then the very pattern of thinking in an inquiry properly called “scientific” would reflect the new physics with its new concept of scientific explanation.  To be able to cope with a scientific problem at all would be to have become able to build it into the conceptual framework of the new physics.

In Concept of the Positron Hanson thus distinguishes three stages in this process of the evolution of a new concept of explanation; they are the black box, the gray-box, and the glass box.  In the initial black-box stage, there is an algorithmic novelty, a new formalism, which is able to account for all the phenomena that an existing formalism can account for.  Scientists use this technique, but they then attempt to translate its results into the more familiar terms of the orthodoxy, in order to provide understanding.  In the second stage, the gray-box stage, the new formalism makes superior predictions in comparison to the older alternative, but it is still viewed as offering no understanding.  Nonetheless it is suspected as having some structure that is in common with the reality it predicts.  In the final glass-box stage the success of the new theory will have so permeated the operation and techniques of the body of the science that its structure will also appear as the proper pattern of scientific inquiry.   Writing in 1958 Hanson said that quantum theory is in the gray-box stage, because scientists have not yet ceased to distinguish between the theory’s structure and that of the phenomena themselves.  This evolution is the gradual adoption of the practice of scientific realism, in which (to mix metaphors) the glass becomes the spectacles through which reality is seen. 

Explanatory language is customarily thought to be explanatory, because it describes the real causes of the phenomena explained. Therefore, the concept of causality also undergoes the kind of evolution that occurs with the concept of explanation.  In the chapter titled “Causality” in Patterns of Discovery Hanson says that cause words are theory-laden; they are the details in an intricate pattern of concepts.  Causes are connected with effects, but only because theories connect them, not because the universe is held together by a cosmic glue.  Questions about the nature of causation are to a large degree questions about how certain descriptive terms in definite contexts coupled together complement and interlock in a pattern of other terms.  The elements of explanation, causation, and theorizing become worked into a comprehensive language pattern.

Scientific Criticism

Hanson’s discussion of scientific criticism is principally concerned with the topic of crucial experiments.  He takes up the topic in a chapter in Concept of the Positron in which he discusses the different concepts of light in the history of physics, and he discusses it again later in a chapter in Perception and Discovery.  Hanson’s rejection of the idea of crucial experiments has its basis in his thesis that observation is theory-laden.  A commonly referenced example of a crucial experiment is Foucault’s 1850 crucial test between the wave and particle concepts of light.  In that experiment Foucault demonstrated that light travels more rapidly in air than in water.  According to the doctrine of the crucial experiment the corpuscular hypothesis should have been banished forever.  But such did not occur.  The photoelectric effect and the Compton effect can only be explained on a corpuscular theory of the nature of light.  The experiments are not crucial, because the observations are important only against the assumptions, theories, and hypotheses that are in the balance before the experiment is performed. 

One of the assumptions is that light cannot be both wave and particle.  The crucial test is a test of the alternative hypotheses together with all of their assumptions, just as in ordinary scientific observation there is a pure registration or sensation plus all of the assumptions necessary to give those sensations meaning.  If we were forced to revise our assumptions, then the outcome of the crucial experiment must be re-interpreted, so that it need not decide against one of the hypotheses.  Some of the most profound revolutions in modern science have consisted not in the criticisms of old hypotheses, but in the criticism of the assumptions underlying the hypotheses.  Crucial experiments are crucial against some hypothesis only in relation to a stable set of assumptions that we do not wish to abandon.    But no set of assumptions is permanently valid.  Hanson says that crucial experiments are out of the same bag as pure observations and uninterpreted facts; they are philosophers’ myths.

Hanson’s discussions of crucial experiments pertain only to theories that may intelligently be disconfirmed.  Although in principle all statements of science are testable and can be falsified, in practice theories often have another use or function.  Following Wittgenstein’s thesis that language may have many uses, Hanson maintains that theories functioning as “pattern statements” supplying a conceptual gestalt will not yield an intelligible statement negating the theory, if the theory is viewed as disconfirmed.  This is because the theory gives the phenomena their intelligibility; and this explains why scientist will not reject a theory, even while they recognize the existence of anomalies that are not intelligible in the theory.  What scientists do in practice is to attempt to save the theory with small modifications or wait until a new and more adequate theory is proposed that explains all that the old theory explains as well as the anomalies to the old theory.  Anomalies do not make scientists give up intelligibility. 

It is for this reason that physicists have not given up the Copenhagen interpretation in spite of the anomalies confronting Dirac’s theory.  Thus Hanson, opposing Bohm in the “Postscript” chapter in Quanta and Reality, states that dropping orthodox quantum theory right now would be to stop doing microphysics altogether.  Then Hanson immediately adds that should the heretics (Bohm et al.) succeed in accounting for everything that orthodox theory now describes, and do so without the divergence difficulties and the renormalization nuisance even without the indeterminacy relations and the irreducibly statistical laws – should they do all this, then physicists of the world will be at their feet, and science will have ascended to a new plane of power and fertility.


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NOTE: Pages do not corresponds with the actual pages from the book