Matter Still Largely Material. (A Response to N.R. Hanson's "The Dematerialization of Matter") Herbert Feigl Philosophy of Science, Vol. 29, No. 1. (Jan., 1962), pp. 39-46. Stable URL: http://links.jstor.org/sici?sici=0031-8248%28196201%2929%3A1%3C39%3AMSLM%28R%3E2.0.CO%3B2-Q Philosophy of Science is currently published by The University of Chicago Press.
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http://www.jstor.org Fri May 18 08:40:16 2007
DISCUSSION
MATTER STILL LARGELY MATERIAL*
(A response to N.R. Hanson's "The Dematerialization of Matter") HERBERT F E I G L University of Minnesota
T h e "dematerialization of matter" in recent physical theory has been welcomed with enthusiasm in various philosophical quarters. Even tough-minded thinkers like Bertrand Russell have interpreted the new conceptions of matter as helpful in overcoming the traditional mind-body dualism. Others have sought comfort in the idea that the indeterminism of quantum physics provides a place for a genuinely free will in a world governed at least in part by statistical laws. T h e much emphasized quantum mechanical inseparability of observing subject (or measuring instrument) from the observed or measured object has been exploited in favor of a mystical union of the knowing subject and his world! Let me make it quite clear at the ouset that 1 do not impute any of these views - which I consider seriously mistaken - to my esteemed friend and symposiast, Professor Hanson. But before I proceed to a discussion of his challenging presentation, I do wish to sap a few words about those misinterpretations. My reason for doing this is simply that, just because I fully acknowledge the profound revolution in scientific thought regarding the nature of matter, I wish to warn against its (metaphysical) exploitation for the solution of philosophical problems. If by "mind" or "mental life" we mean the immediate experiences and the thinking of persons, then no matter what we have learned from recent atomic and quantum physics, the puzzle of the relation between the mental and the physical remains one for logical and epistemological examination. T o be sure, there are results of neurophysiology, as well as of its possible ultimate reduction to physical theory, which are relevant to the scienti$c components of the complex cluster of puzzles that constitutes the mind-body problem1. But as regards the typically philosophical components of the matter-mind problem, I don't find it makes any difference whether we conceive matter along the lines of 17th century or of 20th century physics. The contrasts of objective vs. subjective (public vs. private); spatial vs. non-spatial; quantitative vs. qualitative; non-intentional vs. intentional (in Brentano's sense) remain just as puzzling, even if matter is conceived along the lines of modern quantum mechanics. These contrasts demand a searching analysis if we are to arrive at a coherent account which goes beyond a mere psychophysiological parallelism.
* Received, November,
1961. Cf. my essay "The 'Mental' and the 'Physical' " in Vol. I1 of Minnesota Studies i n the Philosophy of S c i e ~ c e ,( H . Feigl, M . Scriven, and G. Maxwell, eds.), University of MinnesotaPress, Minneapolis, 1958. Also : "Mind-Body not a Pseudoproblem" in S. Hook, ed. : Dimensions of Mind, New York University Press, 1960.
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DISCUSSION
1 am equally slieptical about the significance of the quantum-theoretical interpretation of matter and its indeterminism for the free will problem. I n the first place, I am convinced that the philosophical issue of freewill vs. determinism is largely engendered by easily avoidable conceptual confusions (and is in this respect much less complex and difficult than the mind-body I seriously doubt that the ideas of indeterminacy or of p r ~ b l e m . )Secondly ~ complementarity are helpful in establishing a physical basis for genuinely free choice. Among the philosophizing physicists A.S. Eddington and A.H. Compton3 have in differing ways attempted to link human free choice with indeterminacy, but I think that their arguments are fallacious. However, I must not digress too far from our main topic. Let me then turn to the notions of primary and secondary qualities. I think that, properly revised and reformulated, the distinction still makes perfectly good sense and is useful in an epistemological clarification of the concepts of modern physics. Locke's views, and the similar views of the scientists of the 17th century (Galileo, Newton, Boyle, Gassendi, etc.) can be restated in a form that is not open to Berkeley's criticisms. Shape, size, duration, location, motion. mass, solidity, etc. as apprehended in direct perception are indeed just as "subjective" as are the colors, sounds, odors, tastes, tactual and thermal qualities. Philosophically and scientifically unsophisticated perception ascribes all of these attributes to the "things as they are in themselves." This is the well known story of naive realism. But corresponding to these perceptual properties there are the "objective" attributes which the physical sciences ascribe to matter-as-it-is-conceived on various levels of explanation. And it is the proper task of psychophysics to investigate the lawful dependencies of perceptual qualities on the features of physical reality. (If this be metaphysics, make the least of it! True, the stereotype of "logical positivist" no longer fits me, - if it ever did. Even in the years of the Vienna Circle I was close to a critical realism. However, the then powerful position of Carnap and Schlick silenced me for a while. I t must be remembered that the pre-Vienna Schlick was a critical realist; and Carnap, and even Ayer, have abandoned phenomenalistic positivism. I n the case of Carnap I think that my continued arguments for more than twenty years contributed to the change in his point of view. T f . R.E. Hobart (pseudonym for D.S. Miller), "Freewill as involving Determination, and inconceivable without it" M i n d 43, 1934. University of California Associates, "The Freedom of the Will," reprinted in H. Feigl and W. Sellars, eds., Readings i n Plzilosophical Analysis, New York : Appleton-Century-Crofts, 1949. A. Griinbaum, "Causality and the Science of Human Behavior," in N. Feigl and M. Brodbeck, eds., Readings in the Plzilosoplzy of Science, AppletonCentury-Crofts, New York, 1953. Also : Arthur Pap, "Determinism, Freedom, Moral Responsibility, and Causal Talk," in : S. Hook, ed., Determinism and Freedom, New York University Press, 1958. A.S. Eddington, T h e hTatuve of the Physical I.t70rld, New York : Macmillan, 1932 A H . Compton, T h e Freedom of M a n , S e w Haven, Yalc University Press, 1935. Even the highly sophisticated and more recent views of Hans Reichenbach, "The Freedom of the Will" in : Modern Philosophy of Science, T h e Humanities Press, N.Y., 1950. do not seem to me to carry conviction.
T H E DEMATERIALIZATION OF MATTER
41
My own position in many respects agrees with the realistic views of Keichenbach, Popper, Mehlberg, Griinbaum and Feyerabend; - all of them scientific empiricists ! Since I sense a streak of Berkeleyan phenomenalism in the Copenhagen interpretation of quantum mechanics, and, in accordance with it, in Professor Hanson's views, I feel impelled to argue for realism once more. Of course, I know only too well that the conceptual problems of quantum mechanics are extremely intricate and complex; and I admit there is no easy solution for them anywhere in sight). For the sake of brevity let me assert somewhat dogmatically that it is epistemologically indispensable to distinguish between the qualities of appearance and the attributes ascribed to physical reality on the basis of measurement, experiment and theoretical interpretation. Psychophysically there are varying measures of correspondence between the qualities - sensed (or experienced) and the stimulus properties of physical objects. While agreeing with Berkeley that all sense qualities, be they spatio-temporal, or be they colors, sounds, tastes, odors, etc. are "in the same boat" (viz. in the "boat" of immediate experience), one may nevertheless agree with Locke in the (to be sure, highly qualified) sense that perceptually spatial, temporal, etc. qualities are by and large more reliable cues for the features of objective reality than are the perceptual qualities of color, sound, taste, odor or heat. This should be acceptable even to phenomenalistically oriented positivists who conceive of objective reality as a logical construction out of the data of direct experience. For it is clear that the spatial dimensions (length, breadth, height) of nearby, middle sized physical objects, as determined by measurement may often be fairly accurately judged on the basis of unimplemented sense-impressions. T h e case is different, however, for, e.g., stellar distances, where direct impressions are utterly unreliable, even topologically speaking. I maintain then that there is only a difference of degree in the reliability of experiential cues. T h e whistle of a passing locomotive sounds high in pitch first, and suddenly drops in pitch later. There was no change in the proper frequency of vibrations of the whistle ; but there was a change in the frequency of the sound waves impinging on the ear drum. We have to know about the Doppler effect in order to make the proper ascriptions. A certain shade of green may be experienced under a great variety of stimulus conditions. I t may be produced by monochromatic light, it may result from mixtures of radiation of differing wavelengths; it may be a negative after-image; it might even be produced by direct electric stimulation of a spot in the visual cortex of the brain. The qualities of warm or cold often depend largely on the condition of the experiencing subject. A full-fledged scientific account of perception, - a causal theo~yof perception indeed, -is needed for sorting out the respective contributions of the stimulus objects, the stimulus context, and of the perceiving organism. Experienced qualities or relations thus differ only in their degrees of reliability for the inference of objectively (or intersubjectively, scientifically) confirmable properties of physical reality. In sum, Loclte's concession to Berkeley might well have to be: Allright, we don't perceive the "real", "primary" properties of
42
DISCUSSION
things any more directly than we do the "secondary" ones. So, let us replace the old distinction by a gradation as to reliability. A Loclie redivivus could also point out that the objective spatial order, at least in its topological structure (and in favorable cases in rough approximation, also in its metrical aspects) is often fairly reliably indicated by the impressions of both the visual and the tactual sense-modalities; and to a much lesser degree even the kinesthetic and the auditory data furnish some cues for the objective spatial order. In this respect the situation is different for the colors, sounds, tastes, odors, and thermal properties of physical objects. Only the eye discerns the colors, the ear, the sounds, etc. (That is, unless we are willing to sap that Helen Iceller appreciates music by feeling the vibrations of the piano with her sense of touch). Following W.E. Johnson and C. J. Ducasse we may call properties so discerned "phpsico-psychical" properties, and distinguish them from the "physico-physical" properties which are disclosed by experiment and/or measurement, i.e. by the observation of the interaction of bodies outside the observer's organism. - T h e so-called tertiary qualities, e.g. like the serenity of a landscape, or the attractiveness of a face, are even more unreliable indicators of objective properties. I repeat, one relevant distinction is one of degree only, that is, regarding the reliability of experiential cues for the indication or inference of objective properties or relations. But another distinction, which unfortunately has often been confused with the one just discussed, does need to be made, viz. the distinction between the attributes of perceptual appearance and the attributes of objective reality. Now, the attributes of objective reality are different for different levels of scientific concept-formation and theory-construction. Distances, durations, and masses as conceived in ordinary life or by roadbuilders, architects, carpenters, beer brewers, etc., are essentially of the same logical structure as the distances, durations and masses of experimental classical mechanics. Characterizations of objective realities in terms of merely their physico-psychical properties, are at best only provisionally used, and for the sake of greater reliability and precision rapidly supplanted by characterizations in terms of their physico-physical proper tie^.^ Thus, e.g., we may first judge the acoustical properties of a violin string by the sounds-as-heard; but for an objective scientific characterization we adduce measurements of wave-frequencies and amplitudes. In the course of scientific investigation we come to form many (low-level) dispositional concepts of the physico-physical type. Surface colors initially characterized in terms of their effect on an observer, are replaced by the dispositional concept of selective reflectivity as determined spectroscopically. There is no need here to go into an analysis of the logical structure of dispositional concepts. Whether we explicate them B la Carnap in terms of reduction sentences, or perhaps in terms of causal modalities, is not essential Cf. C. J. Ducasse, Nature, Mind and Death La Salle Illinois : The Open Court Publishing Company, 1951; chapter 15.
THE DEMATERIALIZATION OF MATTER
43
for our purposes. What is essential is the question concerning the logic of the concepts and principles with which we explain dispositional properties; or, what amounts to the same, how we explain the empirical regularities for which the dispositional concepts provide a s11ort-hand formulation. It is in connection with these explanatory concepts and principles that the issue of the "dematerialization of matter" arises. On the level of experimental macro-physics and chemistry, matter clearly has its classical properties, ascribable in terms of the concepts of objective space, time, mass - and of the host of dispositional properties which are quantitatively expressed in the various material constants or parameters (e.g. density, specific heat; refraction index; modulus of elasticity; dielectric constant; magnetic permeability; compressibility; viscosity; electric or thermal conductivity, etc. etc.) It makes perfectly good sense to say, and it is even largely correct, that all these properties, though ultimately known by observation, are existentially independent of any acts of observation. (In this they clearly differ from sensory qualities whose esse is indeed pevcipi.) T o be sure, there are some anomalies. The superfluidity (lack of viscosity) of liquid helium (below the alpha point); the strange behavior of electric "plasma"; the properties of matter under extreme conditiol~sof pressure or temperature; the experimentally verified (relativistic) dependence of mass upon relative velocity; etc., a11 these require some emendations of the Newton-Boyle-Locke conception of matter even on a strictly experimental level. Nevertheless, matter remains still strikingly "material" despite these revisions. The really incisive revolution with its attendant conceptual perplexities arose only in recent atomic and quantum physics. By way of a first impulse one might want to say: matter (macro-matter) is material allright, but the micro-constituents of matter are not material at all. But this will not quite do. The total mass of a macro-object is clearly the sum of the masses of the particles (neutrons, protons, electrons) of which it consists. Except for minor relativistic qualifications this is still correct. T h e rest mass of each of these fundamental particles is experimentally well determined. So, masses do consist sf smaller masses. This much is clearly retained from classical atomistics. 'The diameters of stoms, the size of molecules, the spatial structure of the array of atoms in crystals are equally well established by experimental evidence. Conceptually a little more problematic is the spin of elementary particles. We are told that the spin is to be conceived as just one additional quantumnumber, and that any question concerning the angular velocity of rotation of an electron around its axis is unanswerable, if not meaningless. And there are all the questions (raised by Professor I-Ianson) concerning the diameter of electrons; their genidentity; their precise simultaneous positions and velocities, and so forth. Now, of course, conservative (or should I say "reactionary" ?) thinkers may hope for a restoration of something like the classicalmechanical-electrodynamic world picture on a deeper level of reality. Einstein, de Broglie, Bohm, Vigier, and others, have seriously pursued theoretical or speculative attempts in this direction. Unified field theories in which the
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DISCUSSION
particles are represented as singularities in the field understandably hold a great temptation. However, I would urge philosophers of science not to develop a physical ontology on the basis of what are currently only vague hopes and promissory notes. There is no a priori reason whatever (and hardly any a posteriori one either) to believe that a unified field theory of a strictly deterministic structure will ever be established. I t is quite conceivable that wave mechanics in the statistical interpretation according to the Born rule is here to stay. I t seems to me a much more fruitful task for the philosophers of science (unless they want to become creative theoretical physicists) to concern themselves with the logical analysis of the concepts and postulates of the currently fruitful theories. In connection with the "dematerialization of matter" I suggest, for example the following questions for thorough logical examination. (1) How can we reconcile the usual realistic assumption of the independent existence of physical entities with the dependence of atomic and subatomic processes upon the intervention of measurements ? I t does seem odd to me to assume the occurrence of thermonuclear reactions in the unobserved interior of the sun or of other fixed stars, and at the same time to insist that these micro-processes occur only as a result of the interaction of measuring instruments and measured objects. And although I am decidedly not an "ordinary language philosopher", it does seem to me equally peculiar and objectionable to say that "measurements" are constantly going on in the vast and inaccessible interiors of the stars. (2) Is it not possible to say that wave mechanics in its statistical interpretation presents us with objective probabilities - be they interpreted as propensities or as limits of relative frequency - of micro-events under specifiable macro- or micro-conditions? If so, we may well reconcile ourselves to the << popping into or out of existence" of micro-particles. But as long as they have definite rest-masses, electric charges, etc., is not even micro-matter still pretty material ? (3) Suppose one grants that the some of the concepts applicable to macroobjects are inapplicable to micro-objects; how are we to explicate this inapplicability? Is it a category mistake to apply, e.g. color predicates to electrons I But what precisely is a category mistake from a logical point of view? I n the good old days of Carnap's Logischer Aufbau der Welt, category mistakes were exposed as violations of Russell's rule of types. But this is highly implausible after the abandonment of the phenomenalistic reconstruction. Does it make no sense to ascribe a temperature to a single micro-particle ? Is it meaningless to speak of the simultaneous determination of precise position and momentum ? If so, it should be possible to give a reconstruction of the language of microphysics in which one could clearly see by what sort of rules this kind of nonsense is excluded. I don't insist on one unique reconstruction; but I should like to see at least a few plausible candidates. In the case of the transition from the Newtonian to the Einsteinian concept of simultaneity, it may well be said (and has been said) that a dyadic relation was supplanted by a triadic one. This is surely a change in the syntax of scientific language. I am tempted to
45
THE DEMATERIALIZATION OF MATTER
speak of P-formation rules, if I may use some quasi-Carnapian jargon. Physical theories involve conceptual frameworks, and these determine what is, and what is not a well-formed sentence or formula. And although the choice of some formation rules (other than L-rules) is guided by certain pervasive features of experience, they differ from P-laws or P-postulates in that they are not confirmable or disconfirmable in the sense in which these factual laws or postulates are. T h e P-formation rules are presupposed in the confirmation of scientific hypotheses. (Perhaps this is a slightly Kantian streak in my philosophy but I submit it is the only one a scientific empiricist needs to allow for). (4) Suggestive as this proposal may be, it seems to me to have difticulties too. I t is perplexing (is it not ?) that in the transition from macro- to micro-entities some predicates become inapplicable. How many molecules are needed for a sensible application of the macro-temperature concept? How large must an object be to ascribe to it definite size, shape and location ? How large must a material object be in order to speak sensibly of its speed of rotation ? Or is it silly to raise questions in this manner? Perhaps one way out is suggested by the formula of the indeterminacy principle itself: Ax.Ao w
h.
With inm creasing m (the mass of the particle concerned) the statistical dispersions in the x-coordinate and the velocity v become smaller and smaller, and for any plainly visible or tangible macro-object, the indeterminacies are far below practical measurability. Shall we construe all this in terms of a gradation of meaningfulness ? This would indeed be very odd, or at least extremely awkward. The applicability of such concepts as color, hardness, temperature, specific heat, electric conductivity would form a kind of slippery slope, - clearly present in the upper range, but fading out more or less gradually as we go down the scale toward the micro-entities. I n terms of an alternative reconstruction we might say that the language of quantum meclianics simply does not mesh with the language of classical physics; and that the progress of science consists (as far as logical structure is concerned), in the supplanting of one language by another. T h e older language is then, in principle, completely discarded, once the new language has been adopted. I t is then only in the observational consequences that we find in certain areas practical agreement between the old and the new theory. This may be the germ of a s ~ l u t i o n Still . ~ it would be desirable to spell out in some detail the logical or empirical correspondence of classical and modern concepts wherever such correspondence exists. And it would be even more important to make fully explicit the logical syntax and semantics of microphysics. Do we use a thing-attribute, a space-time-functov, -
If I understand them correctly, R. Carnap in his work since his essay on "The methodological Character of Theoretical Concepts" (IWinn. Studies in The Philosophy of Science, Univ. of Minn. Press, 1956, P.K. Feyerabend, in many publications, culminating in "Explanation, Reduction, and Empiricism," forthcoming in Vol. I11 of Minn. Studies in the Philosophy of Science, Univ. of Minn. Press, 1962, and Wilfrid Sellars, "The Language of Theories," in H. Feigh and I. Madewell, ads., Current Issues in the Philosophy of Science, Holt, Rinehart, and m7inston, Inc., New York, 1961, are tending in this direction.
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DISCUSSION
or an event language ? What are the advantages, what the disadvantages of these various reconstructions ? I t seems to me imperative that we undertake this intriguing and no doubt difficult task in the logic of science. Perhaps I merely reveal my lack of comprehension, but I must confess I cannot make good clear sense out of Niels Bohr's assertions about the inseparability of measuring instrument and measured object in quantum mechanics. What is it then that micromeasurements can inform us about ? If many attributes that we used to take as designated by one-place predicates have to be supplanted by dyadic, triadic or polyadic relations, what are the terms of these relations, an3 what can we say about them except in the context of their relations ? Holism is a highly unclarified notion. Do we really need it in physics (or for that matter in biology)? What 1 am pleading for is a consistent and coherent account that renders justice to what is to be retained of largely "material" matter concepts of 19th century and early 20th century atomic and electronic physics as it is absorbed in modern quantum and wave mechanics. I t is no good to say that the most recent modern physics of Dirac, von Neurnann, Schwinger et al. is a "purely abstract model", and that our mistake is picture-thinking. I don't hanker for pictures. I grant the abstract, unvisualizable character of most physical concepts, classical or modern. But I insist that physics deals with happenings in space-time, and that associated with those happenings there are aspects of mass, charge and motion which leave at least some characteristics of old-fashioned matter unaltered. Well, it is said that a fool can asli more questions than ten wise men can answer. I have asked many questions, and I am certainly no wise man. But even if I am a fool, perhaps there will be an eleventh wise man - possibly my friend Hanson ? - who will answer at least some of my questions ?
