Abstract
This three-part paper comprises: (i) a critique by Halvorson of Bell’s (1973) paper ‘Subject and Object’; (ii) a comment by Butterfield; (iii) a reply by Halvorson. An Appendix gives the passage from Bell that is the focus of Halvorson’s critique.
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Notes
The paper was presented at a symposium in honour of Dirac in September 1972, published in The Physicist’s Conception of Nature (ed. J. Mehra) in 1973, and reprinted in Bell’s collection (1987; second edition 2004, with the same pagination). Compare the Appendix.
Consider, for example, the Bohmian description of a momentum measurement: According to Norsen, “one could ‘turn off’ the potential energy V(x) which confines the electron to the vicinity of the origin...” (Norsen 2017, 196). To echo Bell’s question, exactly where and when is the potential energy turned off?
Agreed, the papers with the best-known of these longer statements of (a) and (b) were written after ‘Subject and Object’: for example, ‘On the impossible pilot-wave’, ‘Speakable and unspeakable...’, ‘Six possible worlds...’, and ‘Against measurement’ [Chs. 17, 18, 20 and 23 of (1987/2004)]. But I thank Chris Timpson for pointing out to me that one also finds earlier statements, in ‘The moral aspect of quantum mechanics’ (from 1966: Ch. 3), in ‘On the hypothesis that the Schrödinger equation is exact’ (from 1971; the revised 1981 version, called ‘Quantum mechanics for cosmologists’, being Ch. 15) and, more briefly, in Section 1 of ‘Introduction to the hidden variable question’ (1971, Ch. 4). Note also: (i) Bell’s 1989 Trieste Lecture, which talks in detail about ‘the shifty split’ and about Dirac (cf. Bassi and Ghirardi 2007), and (ii) the quotes in Ghirardi’s touching memoir (2014).
D’Espagnat suggested these terms in (1976: Ch. 6.2). Nowadays, the point is often made in the literature on decoherence (e.g. Zeh and Joos 2003, 36, 43; Janssen 2008, Sects. 1.2.2, 3.3.2). But it is humbling to recall that the point was already clear, and beautifully expressed, in Schrödinger’s amazing 1935 papers: cf. especially the “cat paradox” paper’s analogy with a school examination (1935, Sect. 13, 335f.).
As it happens, I have no qualms about the sort of classical cosmic inventory envisaged by the last sentence. I agree, of course, that it might well be infinite, and so ungraspable by human minds. But I do not take the propositions—the descriptions, the items in the inventory—to be a part of the cosmos described; and so there is no problem of the inventory itself having to be listed, or of self-reference or regress. But if you have such qualms: rest assured that nothing I, or Bell, have said commits one to such an inventory.
I surmise that von Neumann was articulating the same confidence about the conceptually unproblematic status of classical psychophysics when in his (1932, Ch. VI.1 p. 419) discussion of measurement, he talked about the ‘psycho-physical parallelism’ being undercut by a quantum measurement: a confidence that, I say, was by 1932 well warranted. The point is also familiar in the history of analytical philosophy of mind. Recall McLaughlin’s much-cited account (1992) of how ‘British emergentism’, represented by e.g. C.D. Broad in the mid-1920s, declined not least because the rapid successes of quantum chemistry (e.g. London and Heitler’s work on covalent bonding) undercut Broad’s conjectured configurational forces.
Recall also Shimony’s vivid phrase, ‘closing the circle’, for the endeavour of recovering the ‘manifest image’ of the world—including the definite macro-realm, or at least definite appearances—from the ‘scientific image’ of it. In these terms, my point is that closing the circle seems easier in a world described by classical physics, rather than by quantum physics.
Two supplementary comments. (1) Having broached the topic of the neural correlates of definite experiences, I should note a misgiving about this solution. Even if one accepts that the definiteness of the inanimate macro-realm is a matter of point-particles’ positions being here rather than there, the pilot-wave theory, in order to secure our having definite experiences, presumably requires that an experience being definite–one way rather than another—involves point-particles being in one wave-packet rather than another. But that seems hard to line up with, for example, an edge-detector cell in a cat’s visual cortex either firing or not. For discussion, cf. e.g. Brown and Wallace (2005, Sect. 7, 533–537).
(2): I thank Ronnie Hermens for pointing out that Halvorson’s stressing that any theory ‘needs users’ (i.e. leaves features outside the described system as ‘external’ and ‘up to the physicist’) is echoed in the non-locality literature, especially in the wake of the Jarrett-Shimony distinction between parameter independence and outcome independence. In particular, Seevinck and Uffink make explicit the different theoretical roles of apparatus-settings and outcomes, when they write “to specify how probable it is that Alice will choose one setting [] rather than [another ...] would be a remarkable feat for any physical theory. Even quantum mechanics leaves the question what measurement is going to be performed on a system as one that is decided outside the theory, and does not specify how much more probable one measurement is than another” (2011, Sect. III.B). I would add that besides, one can ‘shift the split’ i.e.‘ move the cut’. That is: one can instead model an apparatus-setting, and the act of choosing a setting, as a deterministic function of the state of the world, and then recover Bell’s theorem, and cousins like the Free Will theorem, by assuming these functions have suitable kinds of independence (Cator and Landsman 2014; especially pp. 784–786; Landsman 2017, especially pp. 101–102). And for a recent judicious defence of the idea that setting dependence is tenable, I recommend Hermens (2019).
Just a couple of examples: Einstein in a 1954 letter: “[Bohr] utters his opinions like one perpetually groping and never like one who believes he is in possession of definite truth (Einstein 1954).” Schrödinger in a 1926 letter: “There will hardly again be a man who has achieved such enormous external and internal success, who in his sphere of work is honored almost like a demigod by the whole world, and yet who remains—I would not say modest and free of conceit—but rather shy and diffident like a theology student. ...this attitude works strongly sympathetically in comparison with the excessive self-confidence that one often finds in the medium-sized stars of our profession. ...[Bohr] is so very considerate and is constantly held back by the fear that others could take an unreserved assertion of his (i.e. Bohr’s) point of view as an insufficient recognition of others’ (in this case, my) contributions.” (translation by H.H., Schrödinger 1926)
I deduce that Bell never spoke with Bohr from his 1988 Omni interview, where he mentions that he once shared an elevator with Bohr, but that did not work up the nerve to speak to him. More generally, a review of Bell’s educational trajectory indicates that he knew very little about the “continental” philosophical and scientific context of Bohr’s work. For details about Bell’s background, see Whitaker (1998; 2016).
In footnote 7, Butterfield mentions Shimony’s project of “closing the circle”, i.e. deriving the manifest image from the scientific image. If the “scientific image” is things as they are in themselves, and the “manifest image” is things as they appear to us, then closing the circle would amount to achieving Bernard Williams’ “absolute conception of reality” (Williams 1978). This noble aspiration was critiqued by, among others, Putnam (1992).
To properly support these general claims, it would be useful to look at funding trends, or changes in physics curricula and textbooks.
I have been unable to find any use of the phrase “measurement problem” before Bohr’s 1946 article. However, the issue was already being discussed by Bohr, Schrödinger, etc. in the 1920s.
A precise notion of “classical context” emerges from Howard’s (1979) explication of Bohr, and more recently it has been developed by Bub, Clifton, Dickson, Halvorson, and Landsman, among others. While Bohr does not use the exact phrase “classical context”, and does not usually explicate such notions mathematically, he does say that classical concepts are needed to specify the “conditions of description” (betingelser for beskrivelse), and thereby establish a boundary between subject and object. For a clear and modern discussion of these issues, see Landsman (2006).
A similar kind of contextualist view can be found in the work of Greta Hermann (see Crull 2017). Bohr and Hermann’s ideas have roots in Helmholtz, who stressed that knowledge of our physical constitution and situation should be used to interpret the data we receive from our senses (see Patton 2019). In a forward-looking direction, various “perspectivalist” interpretations of QM are based on ideas similar to those of Bohr and Hermann. See e.g. Dieks (2019) and Laudisa and Rovelli (2019).
Bernstein (2011) points out that Bell could not read von Neumann’s text until it was translated to English in 1955.
References
Bassi, A., and G. Ghirardi. 2007. The Trieste Lecture of John Stewart Bell. Journal of Physics A: Mathematical and Theoretical 40: 2919–2933. https://doi.org/10.1088/1751-8113/40/1/002.
Bell, J. 1973. Subject and object. In Bell (1987/2004), Chapter 5.
Bell, J. 1987/2004. Speakable and unspeakable in quantum mechanics. Cambridge: Cambridge University Press.
Bell, J. 1990. Against measurement. Physics World 3: 33–40.
Bernstein, J. 2011. Bell and von Neumann. arXiv:1102.2222a
Bohr, N. 1928. Das Quantenpostulat und die neuere Entwicklung der Atomistik. Naturwissenschaften 16: 245–257. https://doi.org/10.1007/BF01504968 Translated as as ‘The quantum of action and the description of nature’ in Bohr (1934), Atomic Theory and the Description of Nature. Cambridge: Cambridge University Press.
Bohr, N. 1946. Om maalingsproblemet i atomfysikken. In Feststrift to N.E. Nørlund in Anledning af hans 60 Aars Fødselsdag den 26. Oktober 1945 fra danske Matematikere, Astronomer og Geodœter, Anden Del. Ejnar Munksgaard, Copenhagen, pp. 163–167. [Reprinted with translation ‘On the problem of measurement in atomic physics’ in Niels Bohr Collected Works, Vol 11, pp. 655–666. https://doi.org/10.1016/S1876-0503(08)70438-9]
Butterfield, J. 2018. Peaceful coexistence: examining Kent’s relativistic solution to the quantum measurement problem. In Reality and measurement in algebraic quantum theory (Proceedings of the 2015 Nagoya Winter Workshop), ed. M. Ozawa et al. (Springer Proceedings Maths and Statistics, 261), 277–314. https://doi.org/10.1007/978-981-13-2487-1, arXiv:1710.07844; http://philsci-archive.pitt.edu/14040
Butterfield, J. and B. Marsh. 2019. Non-locality and quasiclassical reality in Kent’s formulation of relativistic quantum theory. Journal of Physics: Conference Series (DiCE 18). https://doi.org/10.1088/1742-6596/1275/1/012002
Brown, H., and D. Wallace. 2005. Solving the measurement problem: de Broglie-Bohm loses out to Everett. Foundations of Physics 35: 517–540.
Cator, E., and N. Landsman. 2014. Constraints on determinism: Bell versus Conway–Kochen. Foundations of Physics 44: 781–791.
Crull, E. 2017. Greta Hermann and the relative context of observation. In Greta Hermann—Between Physics and Philosophy, ed. G. Bacciagaluppi and E. Crull, 149–169. Berlin: Springer. https://doi.org/10.1007/978-94-024-0970-3_10.
D’Espagnat, B. 1976. Conceptual Foundations of Quantum Mechanics. Hoboken: John Wiley.
Dieks, D. 2019. Quantum reality, perspectivalism and covariance. Foundations of Physics 49: 629–646.
Einstein, A. 1954. Letter to Bill Becker, March 20. Albert Einstein Archives, Hebrew University Jerusalem.
Favrholdt, D. 2009. Filosoffen Niels Bohr. Copenhagen: Informations Forlag.
Faye, J. and H. Folse. 2017. Niels Bohr and the philosophy of physics: twenty-first-century perspectives. London: Bloomsbury Academic.
Faye, J. 2019. Copenhagen interpretation of quantum mechanics. Stanford Online Encyclopedia of Philosophy. https://plato.stanford.edu/entries/qm-copenhagen/
Ghirardi, G. 2014. John Stuart Bell: recollections of a great scientist and a great man. arxiv:1411.1425
Halvorson, H. and R. Clifton. 1999. Maximal Beable subalgebras of quantum-mechanical observables. International Journal of Theoretical Physics 38: 2441–2484. http://philsci-archive.pitt.edu/65/
Halvorson, H. and R. Clifton. 2002. Reconsidering Bohr’s reply to EPR. In Non-locality and modality, eds. J. Butterfield and T. Placek: NATO Science Series (Series II: Mathematics, Physics and Chemistry), vol 64. Dordrecht: Springer.
Hermens, R. 2019. An operationalist perspective on setting dependence. Foundations of Physics 49: 260–282.
Howard, D. 1979. Complementarity and ontology: Niels Bohr and the problem of scientific realism in quantum physics. PhD Thesis. Boston: Boston University.
Howard, D. 2004. Who invented the Copenhagen interpretation? A study in mythology. Philosophy of Science 71: 669–682.
Janssen, H. 2008. Reconstructing reality: environment-induced decoherence, the measurement problem, and the emergence of definiteness in quantum mechanics. On Pittsburgh archive at http://philsci-archive.pitt.edu/4224.
Kent, A. 2014. Solution to the Lorentzian quantum reality problem. Physical Review A 90: 012107. arXiv: 1311.0249.
Kent, A. 2015. Lorentzian quantum reality: postulates and toy models. Philosophical Transactions of the Royal Society A 373: 20140241. arxiv: 1411.2957.
Kent, A. 2017. Quantum reality via late-time photodetection. Physical Review A 96: 062121. https://doi.org/10.1103/PhysRevA.96.062121
Landsman, N. 2006. When champions meet: rethinking the Bohr–Einstein debate. Studies in History and Philosophy of Modern Physics 37: 212–242. https://doi.org/10.1016/j.shpsb.2005.10.002.
Landsman, N. 2017. Foundations of quantum theory. Springer. https://link.springer.com/book/10.1007/978-3-319-51777-3
Landsman, N. 2017. On the notion of free will in the free will theorem. Studies in History and Philosophy of Modern Physics 57: 98–103.
Laudisa, F. and C. Rovelli. 2019. Relational quantum mechanics. In Stanford online encyclopedia of philosophy. https://plato.stanford.edu/entries/qm-relational/
Mann, C. and R. Crease. 1988. John Bell particle physicist (interview). Omni 10(8): 84–92 and 121.
McLaughlin, B. 1992. The rise and fall of British emergentism. In Emergence or reduction?, ed. A. Beckerman, H. Flohr, and J. Kim. Berlin: de Gruyter. Reprinted in M. Bedau and P. Humphreys (eds.) (2008), Emergence: contemporary readings in philosophy and science, MIT Press: Bradford Books.
Norsen, T. 2017. Foundations of quantum mechanics. Berlin: Springer.
Patton, L. 2019. Perspectivalism in the development of scientific observer-relativity. In The Emergence of Relativism, ed. M. Kusch, et al., 63–78. London: Routledge.
Putnam, H. 1992. Renewing philosophy. Cambridge: Harvard University Press.
Schrödinger, E. 1926. Letter to Wilhelm Wien, August. Wien Archiv, Deutsches Museum, Munich
Schrödinger, E. 1935. ‘The present situation in quantum mechanics’: a translation of Schrödinger’s “cat paradox”’ paper (trans: J D. Trimmer). Proceedings of the American Philosophical Society 124, (Oct. 10, 1980), pp. 323–338; American Philosophical Society. http://www.jstor.org/stable/986572
Seevinck, M., and J. Uffink. 2011. Not throwing out the baby with the bathwater: Bell’s condition of local causality mathematically ‘sharp and clean’. In Explanation, prediction, and confirmation, vol. 2, ed. D. Dieks, W. Gonzalez, S. Hartmann, T. Uebel, and M. Weber. The philosophy of science in a European perspective. Berlin: Springer.
von Neumann, J. 1932. Mathematical foundations of quantum mechanics, Princeton: University Press. (English translation 1955, reprinted in the Princeton Landmarks series 1996).
Wallace, D. 2014. The emergent multiverse: quantum theory according to the Everett interpretation. Oxford: Oxford University Press.
Whitaker, A. 1998. John Bell and the most profound discovery of science. Physics World. https://physicsworld.com/a/john-bell-profound-discovery-science/
Whitaker, A. 2016. John Stewart Bell and twentieth-century physics. Oxford: Oxford University Press.
Williams, B. 1978. Descartes: the project of pure enquiry. London: Penguin Books.
Wigner, E. 1962. Remarks on the mind-body problem. In The scientist speculates, ed. I.J. Good. London: Heinemann.
Zeh, H.-D. 1970. On the interpretation of measurement in quantum theory. Foundations of Physics 1: 69–76.
Zeh, H.-D., E. Joos, et al. 2003. Decoherence and the appearance of a classical world in quantum theory, 2nd ed. Berlin: Springer.
Zinkernagel, H. 2016. Niels Bohr on the wave function and the classical/quantum divide. Studies in History and Philosophy of Modern Physics 53: 9–19.
Acknowledgements
By H. Halvorson: For discussion, thanks to Jeremy Butterfield, Erik Curiel, Ronnie Hermans, Klaas Landsman, and Chris Timpson. For clarification of Bohr’s view, I am indebted to the work of David Favrholdt. By J. Butterfield: I am very grateful to: Adam Caulton, Erik Curiel, Sebastian De Haro, Henrique Gomes, James Ladyman, Klaas Landsman, Ruward Mulder, Bryan Roberts, Simon Saunders, Nic Teh; and especially to Hans Halvorson, Ronnie Hermens and Chris Timpson.
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Appendix: What Bell Says
Appendix: What Bell Says
Here, for convenience and completeness, is the beginning of Bell’s (1973) paper, as reprinted in his (1987/2004). This is the passage on which Part I concentrates. The paper was for a symposium in honour of Dirac. But note that the CERN preprint from September 1972 (available at: http://cds.cern.ch/record/610096/files/CM-P00058496.pdf?version=1) has an opening sentence deleted from the reprint, namely: ‘I have been invited to contribute under this heading.’ So the form of the invitation to Bell might explain, at least in part, why he here cast the measurement problem in the language of ‘subject’ and ‘object’. It is possible that the symposium organizers were influenced in their choice by Bohr’s frequent use of the subject/object terminology, which traces back to more general epistemological discussions in the 19th century.
The subject-object distinction is indeed at the very root of the unease that many people still feel in connection with quantum mechanics. Some such distinction is dictated by the postulates of the theory, but exactly where or when to make it is not prescribed. Thus in the classic treatise of Dirac we learn the fundamental propositions:
...any result of a measurement of a real dynamical variable is one of its eigenvalues,
...if the measurement of the observable \(\xi\) for the system in the state corresponding to \(| x \rangle\) is made a large number of times, the average of all the results obtained will be \(\langle x | \xi | x \rangle\)...,
...a measurement always causes the system to jump into an eigenstate of the dynamical variable that is being measured....
So the theory is fundamentally about the results of ‘measurements’, and therefore presupposes in addition to the ‘system’ (or object) a ‘measurer’ (or subject). Now must this subject include a person? Or was there already some such subject-object distinction before the appearance of life in the universe? Were some of the natural processes then occurring, or occurring now in distant places, to be identified as ‘measurements’ and subjected to jumps rather than to the Schrödinger equation? is ‘measurement’ something that occurs all at once? Are the jumps instantaneous? And so on.
The pioneers of quantum mechanics were not unaware of these questions, but quite rightly did not wait for agreed answers before developing the theory. They were entirely justified by results. The vagueness of the postulates in no way interferes with the miraculous accuracy of the calculations. Whenever necessary a little more of the world can be incorporated into the object. In extremis the subject-object division can be put somewhere at the ‘macroscopic’ level, where the practical adequacy of classical notions makes the precise location quantitatively unimportant. But although quantum mechanics can account for these classical features of the macroscopic world as very (very) good approximations, it cannot do more than that. [footnote omitted] The snake cannot completely swallow itself by the tail. This awkward fact remains: the theory is only approximately unambiguous, only approximately self-consistent.
It would be foolish to expect that the next basic development in theoretical physics will yield an accurate and final theory. But it is interesting to speculate on the possibility that a future theory will not be intrinsically ambiguous and approximate. Such a theory could not be fundamentally about ‘measurements’, for that would again imply incompleteness of the system and unanalyzed interventions from outside. Rather it should again become possible to say of a system not that such and such may be observed to be so but that such and such be so. The theory would not be about ‘observables’ but about ‘beables’. These beables need not of course resemble those of, say, classical electron theory; but at least they should, on the macroscopic level, yield an image of the everyday classical world...
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Halvorson, H., Butterfield, J. John Bell on ‘Subject and Object’: An Exchange. J Gen Philos Sci 54, 305–324 (2023). https://doi.org/10.1007/s10838-021-09594-y
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DOI: https://doi.org/10.1007/s10838-021-09594-y