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Kuhn's STRUCTURE

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I recently eliminated all of those essay-threads that I had created for the Boydstun Corner at OBJECTIVIST LIVING because the advertising at that site has made it no longer appropriate for sustained serious compositions and reading thereof. I've been making some of those old studies available at OBJECTIVISM ONLINE, and I think this one fits well in this sector.

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The Structure of Scientific Revolutions

Thomas S. Kuhn

I. Searching

In Thomas Kuhn's view, observation and experiment are essential to scientific understanding of the world (1990 [S], 42), but observation and experiment, in an established science, are guided and made sense of by one or another paradigm (S 109). Under the notion paradigm, Kuhn means to include theories, theoretical definitions, natural laws, particular models, and preeminently, concrete problem-solutions that exemplify theory and law, giving them empirical content (S 182–89). Scientific concepts, laws, and theories are presented and comprehended not in the abstract alone; but with applications to some concrete range of phenomena, purely natural, such as freely falling bodies, or natural-within-contrivance, such as pendulums (S 46–47, 187–91).

Normal science undertakes ever more exact and subtle experimental and observational investigation of "facts that the paradigm has shown to be particularly revealing of the nature of things" (S 25), determination of facts that "can be compared directly with predictions from the paradigm theory" (S 26), and articulation of the paradigm theory (S 27–29). These are roles of observation in science, I should say, even if we should reject Kuhn's distinction between normal and revolutionary periods of science as too sharply drawn.

One illustration of normal science would be the ongoing investigation of neutrinos. The existence of neutrinos is a fact established in 1956 (they were then detected) within the theoretical framework of quantum mechanics and detail conservation of energy. The characteristics of neutrinos are facts particularly revealing of the nature of elementary-particle interactions. The further, more refined determination of neutrino characteristics bears on the correctness and further refinement of a number of interconnected paradigms. Elaborate observations of solar neutrinos the past few decades provide quantitative constraints on models of nuclear reactions in the sun's core and on models of the sun's magnetic fields. And they provide constraints on the fundamental theory of neutrinos and of the electronuclear forces of nature (Bahcall 1990). Elaborate observations of cosmic neutrinos, these past few years [1], to ascertain whether they change flavors, hence whether they possess nonzero mass, inform efforts toward a Grand Unified Theory that may eventually supercede or subsume the Standard Model for elementary particles and their forces (Kearns, Kajita, and Totsuka 1999; Feldman and Steinberger 1991; Weinberg 1999). And they bear on current cosmology, under purview of general relativity.

Other normal-science investigations framed under the paradigm of general relativity are these: The finding of pulsar binary neutron stars has yielded, as hoped, empirical data for comparison with predictions from general relativity in the context of strong gravitational fields, predictions such as the rate of the orbital precession of the major axis of the stars' elliptical orbit and red-shifting of the pulse-clock (Piran 1995). Observation of quasi-periodic X-ray emissions from neutron stars pulling in matter from gaseous companion stars are yielding data indicating that, as predicted by general relativity (contrary the prediction from Newtonian gravitation), there is, just outside the neutron star, an innermost circular orbit for captured gas (Cowen 1998). Black holes are entities conceived and cultured solely by general relativity. Astronomical search for black holes and their distinctive features may yield an overwhelming vindication of general relativity (Lasota 1999).

There are three points made by Kuhn concerning the role of observation in science with which I should take some issue. One is his claim that "no part of the aim of normal science is to call forth new sorts of phenomena" (S 24). "Even the [normal-science] program whose goal is paradigm articulation does not aim at the unexpected novelty" (S 35). "Normal science does not aim at novelties of fact or theory and, when successful, finds none" (S 52). But scientists will be human, chronically so, hoping to catch something unexpected and momentous in their instruments, not only expected and readily comprehended phenomena. X-ray astronomer Bruno Rossi writes: "The initial motivation of the experiment which led to this discovery . . . was a subconscious trust of mine in the inexhaustible wealth of nature, a wealth that goes far beyond the imagination of man. This meant that, whenever technical progress opened up a new window into the surrounding world, I felt the urge to look through this window hoping to see something unexpected" (1977, 39).

Kuhn does say that "without the special apparatus that is constructed mainly for anticipated functions, the results that lead ultimately to novelty could not occur" (S 65, emphasis added). So I should productively construe the statements of his that I have quoted in the preceding paragraph as delineation of the strain that he calls normal science which in truth is found within a broader, richer actual practice of science.

Kuhn errs secondly, though only slightly, in his contention that "the act of judgment that leads scientists to reject a previously accepted theory is always based upon more than a comparison of that theory with the world. The decision to reject one paradigm is always simultaneously the decision to accept another, and the judgment leading to that decision involves the comparison of both paradigms with nature and with each other" (S 77, further, 147). Not always so. We continue to test empirically whether any mass-energy can be transported faster than vacuum c (Alväger, Farley, Kjellman and Wallin 1964; Brecher 1977; Chiao, Kwait, and Steinberg 1993). Some of these experiments, in the last two decades, have helped to articulate more finely the light-speed postulate of relativistic kinematics. But it is perfectly possible that such tests in the future could dispositively contradict the postulate. That would be the demise of special relativity regardless of the existence of competitor theories. Without viable alternative kinematics already on the stage or in the wings, what should we do if the light-speed postulate were empirically refuted? We should take our cues from the particulars of the failure and from our old, very successful special-relativity kinematics, and then develop a new and better kinematics.

Again, we continue to test a principle of general relativity, the principle of the equivalence of inertial and gravitational mass. These tests are not simply tests that help us articulate the paradigm, as when we search the heavens for evidence bearing on whether Einstein's field equations should include a nonzero cosmological constant (Krauss 1999; Cowen 2000). No, tests of the equivalence of inertial and gravitational mass cut to the quick of general relativity (Wald 1984, 8, 66–67; Ciufolini and Wheeler 1995, 13–18, 90–116). As I understand it, if gravitational and inertial mass are not precisely equivalent, then gravity cannot rightly be made geometric. And we have no viable alternative (nongeometric) to general relativity waiting in the wings. Were gravitational and inertial mass shown inequivalent by experiment or observation, then theoretical physicists would scramble to construct a replacement theory. We need not already have a competing theory to prefer over general relativity in order to reject the latter on experimental or observational grounds [2].

II. Seeing

Kuhn errs thirdly, and most seriously, in his (inconstant) denial that in our scientific observations we can always separate and adequately express what we literally perceive and what we take those percepts to indicate. Having learned prevailing scientific concepts, theories, and natural laws under exemplifying concrete observational applications, one is not able to see the phenomena in those applications entirely freely of the prevailing conceptual apparatus (S 46–47, 111–12, 186–89). Scientific observational phenomena are to some extent inextricably structured by the scientific, theoretical paradigm under which one is operating (S 111–35, 147–50).

"Looking at a bubble-chamber photograph, the student sees confused and broken lines, the physicist a record of familiar subnuclear events" (S 111). To enter the physicist's scientific observational world, the student undergoes "transformations of vision," like coming "to see a new gestalt." Hardly. Throughout the student's entry into the observational world of physics, all participants easily, routinely, and expressly distinguish between what of the physicist's observational world is commonsense perception and what is scientific interpretation, however automatic the latter may become (cf. S 196–98).

A bubble-chamber photograph provides detailed records of particle events "in a form that experienced physicists can interpret at a glance" (Breuker et al. 1991, 61). The photographs from bubble, cloud, or spark-streamer chambers never do yield a strictly perceptual particle-interaction gestalt in the way, say, that an X-ray photograph of a hand yields a strictly perceptual hand-skeleton gestalt. In the hand X-ray, given our ontogeny and our ordinary visual experience with hands, we are required to see the hand-in-the-image. We can tell ourselves, truly, that what is before us when we see the hand-in-the-image is only the trace of a hand, shadows of hand preserved on film, but we cannot avoid seeing the hand-in-the-image all the same. That is our perceptual constitution. Gestalt shifts too, such as in the Necker cube, are mandated by our primate perceptual constitution. We can tell ourselves that before us are only lines on paper, but we are required to see one cube or the other, with alternations every few seconds (Logothetis 1999). Contemporary elementary-particle tracking is mediated by vast electronic and computer processing systems, embodying painstaking deliberate interpretations. What is perceptually obligatory in the resulting computer-image displays are things like colors, lines, and 3D perspectives; all of these, self-conscious visual aids to scientific, interpretive observation.

Kuhn writes: "Since remote antiquity most people have seen one or another heavy body swinging back and forth on a string or chain until it finally comes to rest. To the Aristotelians, who believed that a heavy body is moved by its own nature from a higher position to a state of natural rest at a lower one, the swinging body was simply falling with difficulty. Constrained by the chain, it could achieve rest at its low point only after a tortuous motion and a considerable time. Galileo, on the other hand, looking at the swinging body, saw a pendulum, a body that almost succeeded in repeating the same motion over and over again ad infinitum." (S 118–19)

To be sure, Kuhn was "acutely aware of the difficulties created by saying that when Aristotle and Galileo looked at swinging stones, the first saw constrained fall, the second a pendulum" (S 121). Yet Kuhn will not let go his continual equivocation on see and its cognates (S 196–97). He maintains that an embracer of the new paradigm of mechanics—such was Galileo—is not an interpreter of swinging stones as pendulums, but "is like a man wearing inverted lenses," like a man who's vision has adapted to those lenses (S 122). "Galileo interpreted observations on the pendulum, Aristotle observations on [constrained] falling stones" (ibid.). That is inaccurate, I should say. Rather, Galileo and we interpret swinging stones as pendulums, on which we then make further interpretative observations. Similarly, one may interpret the swinging stone as in Aristotelian mechanics, as a constrained body working its way to the lowest feasible point. We can deliberately, with training, switch our interpretative perspectives: Aristotelian, Galilean, Newtonian, Lagrangian.  Kuhn suggests that the contemporary scientist "who looks at a swinging stone can have no experience that is in principle more elementary than seeing a pendulum. The alternative is not some hypothetical 'fixed' vision, but vision through another paradigm, one which makes the swinging stone something else" (S 128). I suggest, to the contrary, that developmentally, epistemologically, and evidentially, it is a swinging stone that is most elementary for everyone. It is with respect to analysis that we "see" (take) the pendulum as most elementary.

I do not mean to contradict Kuhn's thesis that scientists do not come to reject scientific theories on account of uninterpreted observations (e.g. S 77). We can recognize that and assimilate that without conflating what we literally perceive and what we make of those percepts in thought.

III. Saying

According to Kuhn, "there can be no scientifically or empirically neutral system of language or concepts" (S 146). Moreover, since we have no rudimentary paradigm-neutral observation language, the pendulum and constrained fall must be simply different perceptions, rather than "different interpretations of the unequivocal data provided by observation of a swinging stone" (S 126). Kuhn has in mind "a generally applicable language of pure percepts," where, by the term percepts, he apparently thinks not of swinging stones, but of more primitive constituents that compose our perceptions of swinging stones. Attempts to construct such a language of pure percepts have not fully succeeded, and anyway, all such projects "presuppose a paradigm, taken either from current scientific theory or from some fraction of everyday discourse, . . . . [thereby yielding] a language that—like those employed in the sciences—embodies a host of expectations about nature and fails to function the moment these expectations are violated" (S 127).

I should say, with Willard Quine, that we do indeed have a trustworthy scientifically neutral system of observation language appropriate and necessary for the physical sciences. This is not a rarified, fully reductive language of "pure percepts," but a natural language of posited objects and events (1969 [EN], 74–79; 1995a [N], 252, 254; 1995b [SS], 10–21, 27–29, 35–42; cf. 1951, 293–98). Swinging body and pendulum are both legitimate expressions of things observed[3], the former providing a fallback in cases of dispute over the latter. "What counts as an observation sentence varies with the width of community considered. But we can always get an absolute standard by taking in all speakers of the language, or most" (EN 88; also N 255; SS 22, 42–45). Pendulum, damped harmonic oscillator, and electron-positron track may be rightly spoken of as observed in the narrower, scientific community. But when necessary, scientists can shift gears and recognize those items as interpretations of more widely accepted and developmentally prior observed items.

Our broadest and most rudimentary observation language is our language of everyday experience, in which we report "it is raining" or "the iron is on" and in which we generalize "swinging suspended bodies return to rest" or "if it is snowing, then it is cold" (N 252, 254–55; SS 22–26). That last ordinary observation sentence is an example of what Quine calls an observation categorical, which is an empirically testable hypothesis, standing (as Popper would have it) as not yet shown false. Quine supposes, reasonably I think, that an empirically testable scientific hypothesis can be cashed out as an elementary observation categorical (N 255; SS 43–47). The detection of cosmic background microwave radiation, for example, cashes to visible records of activities in an antenna (which antenna cashes to . . . ). Quine realizes, of course, that scientists do not trace all the links from their hypothesis to observational categorical. "Still, the deduction and checking of observation categoricals is the essence, surely, of the experimental method, . . . . [and it remains] that prediction of observable events is the ultimate test of scientific theory" (N 256).

Quine recognizes that some hypotheses thus far not testable are accepted, rationally, even in the hard sciences. They may be accepted because "they fit in smoothly by analogy, or they symmetrize and simplify the overall design. . . . Moreover, such acceptations are not idle fancy; their proliferation generates, every here and there, a hypothesis that can indeed be tested. Surely this is the major source of testable hypotheses and the growth of science" (N 256; also SS 49). Can we test whether spacetime is curved? Well, yes, indirectly, more and more, we can.

Kuhn overrated the difficulties of vocabulary translations between alternative paradigms (S 149, 201). He did seem to allow that eventually translation can be effected (S 201–3). Such has been effected between Newtonian gravitational theory and general relativity, and gradually physics has attained more and more tests between those deep and grand theories, tests such as that for an innermost circular orbit about a neutron star.

 

Notes

1.  This study was composed in 2000.

2.   Hilary Putnam points out that Kuhn exaggerates in asserting that a paradigm can never be overthrown in the absence of a competitor paradigm. But Putnam then deflates the demerit of the exaggeration by posing as a hypothetical counterexample to Kuhn's universal claim only a Goodmanesque scenario: the world simply starts to behave radically differently. Barring such an implausible scenario, Putnam then expressly affirms the Kuhnian generalization at issue (Putnam 1974, 69–70). My counterexample scenarios (failure of light-speed postulate or failure of principle of equivalence) are intended to be entirely, mundanely realistic.

3.  Rudolf Carnap (1966) likewise recognized that what in one context of inquiry should be taken as inferred from what was observed could in another context be rightly taken as simply observed (Suppe 1977, 47).

 

References

Alväger, T., Farley, F.J.M., Kjellman, J., and I. Wallin 1964. Test of the Second Postulate of Special Relativity in the Gev Region. Physics Letters 12:260.

Bahcall, J.N. 1990. The Solar-Neutrino Problem. Sci. Amer. (May):54–61.

Brecher, K. 1977. Is the Speed of Light Independent of the Velocity of the Source? Phy. Rev. Ltrs. 39(17):1051–54.

Breuker, H., Drevermann, H., Grab, C., Rademakers, A.A., and H. Stone 1991. Tracking and Imaging Elementary Particles. Sci. Amer. (Aug):58–63.

Chiao, R.Y., Kwait, P.G., and A.M. Steinberg 1993. Faster than Light? Sci. Amer. (Aug):52–60.

Ciufolini, I., and J.A. Wheeler 1995. Gravitation and Inertia. Princeton: University Press.

Cowan, R. 1998. All in the Timing. Sci. News 154:318–19.

——. 2000. Revved-Up Universe. Sci. News 157:106–8.

Feldman, G.J., and J. Steinberger 1991. The Number of Families of Matter [= Three]. Sci. Amer. (Feb):70–75.

Kearns, E., Kajita, T., and V. Totsuka 1999. Detecting Massive Neutrinos. Sci. Amer. (Aug):64–71.

Krauss, L.M. 1999. Cosmological Antigravity. Sci. Amer. (Jan):52–59.

Kuhn, T.S. 1990 [1970, 1962]. The Structure of Scientific Revolutions. 2nd ed. Chicago: Univerity Press.

Lasota, J-P. 1999. Unmasking Black Holes. Sci. Amer. (May):40–47.

Logothetis, N.K. 1999. Vision: A Window on Consciousness. Sci. Amer. (Nov):69–75.

Piran, T. 1995. Binary Neutron Stars. Sci. Amer. (May):53–61.

Putnam, H. 1974. The "Corroboration" of Theories. In Scientific Revolutions. I. Hacking, editor. 1981. New York: Oxford University Press.

Quine, W.V.O. 1951. Two Dogmas of Empiricism. In Philosophy of Science: The Central Issues. M. Curd and J.A. Cover, editors. 1998. New York: W.W. Norton.

——. 1969. Epistemology Naturalized. In Ontological Relativity and Other Essays. New York: Columbia University Press.

——. 1995a. Naturalism, or, Living within One's Means. Dialectica 49(2–4):251–61.

——. 1995b. From Stimulus to Science. Cambridge, MA: Harvard University Press.

Rossi, B. 1977. X-Ray Astronomy. Daedalus 106(4):37–58.

Suppe, F. 1977 [1973]. The Search for Philosophic Understanding of Scientific Theories. In The Structure of Scientific Theories. 2nd. ed. Urbana: University of Illinois Press.

Wald, R.M. 1984. General Relativity. Chicago: University Press.

Weinberg, S. 1999. A Unified Physics by 2050? Sci. Amer. (Dec):68–75.

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