Contribution
The first assessment, from philosophy of physics, of agential realism’s claim to quantum-mechanical origin (§1). It shows that Barad’s Bohr departs from every reading of Bohr in the literature, realist and antirealist alike; that quantum mechanics admits interpretations with very different metaphysics; and that agential realism’s handling of measurement differs from the interpretation Barad names as closest in a way that leaves it without an answer to the measurement problem.
Key insight
Barad’s central move is to promote Bohr’s phenomenon from an epistemic notion to the ontological primitive. Bohr: “I advocated the application of the word phenomenon exclusively to refer to the observation obtained under specific circumstances, including an account of the whole experimental arrangement” (Bohr 1949, 237–238; §3). For Bohr the relata come first: “both atomic objects and instruments are real, and as such they figure as relata in a sentence like ’… is recorded to have position p in relation to …’” (§3). Barad has relations without preexisting relata; Bohr has relational properties of real relata.
Assumptions
- Exegesis of Bohr from his collected writings (1937–1958 texts), set against the secondary literature (Folse, Faye, Favrholdt, Howard, Zinkernagel, Halvorson, Petersen).
- A dispositional reading of Bohmian mechanics (Belot 2012; Esfeld et al. 2014), adopted to simplify the comparison (a note to §5).
- The measurement problem as standardly posed: why one value rather than another from an improper mixture.
Key results
§2: agential realism as Barad presents it
Complementarity: complementary properties are meaningful only relative to the setup that measures them (Bohr’s contextualism). Barad: “position” “is a property of the phenomenon—the inseparability of ‘observed object’ and ‘agencies of observation’” (2003, 814), and “phenomena are ontologically primitive relations—relations without preexisting relata” (2003, 815). Barad’s technical ground is entanglement of object and apparatus at measurement: “phenomena are the ontological entanglement of objects and agencies of observation” (2007, 309). From it she derives the rejection of the “metaphysics of individualism” (2007, 195), of entity realism (she rejects Hacking’s even), and of the dualisms of subject–object, knower–known and word–world. A note on apparatuses quotes her: “apparatuses are the material conditions of possibility and impossibility of mattering; they enact what matters and what is excluded from mattering” (2007, 148). Another note: the separation of object and apparatus “is not fixed; a view that Heisenberg advocates in opposition to Bohr” (Bächtold 2017; Schlosshauer and Camilleri 2017). A third, after Vetlesen: what intra-actions involve “and how they enact the different configurations … are never sufficiently explicated; especially beyond a laboratory setting”.
§3: Bohr on phenomena and realism
- Bohr distinguishes object, instrument, measurement and phenomenon; a phenomenon is “how the quantum object appears during the interaction with a particular measuring instrument”, “the manifestation of a property that only exists in virtue of the interaction”.
- “Barad misreads Bohr as if he was saying that, say, the position is a property of the phenomenon”. “It is beyond doubt that Bohr regarded phenomena to be derivative from a pre-existing experimental set-up”, an “epistemological integration” of object and apparatus that keeps “their ontological separateness”.
- Bohr warns that the observer cannot “influence the events which may appear under the conditions he has arranged” (1949, 223): the experimenter chooses the experiment and nothing more. “Barad’s strong notion of intra-actions enacting cuts within the ontologically primitive phenomena finds no counterpart in Bohr’s interpretation.”
- The realist readings of Bohr make him an entity realist (Folse 1986), which “defeats rather than supports the ontological relational holism of agential realism”; Faye’s “objective antirealist” Bohr also never denied atomic objects. Barad cites Folse as company in a “minority view”, but their disagreement is not cosmetic. Favrholdt’s language-dependent realism is the nearest to Barad’s.
- Bohr never spoke of collapse and treated the wave function as symbolic; “For Bohr there was no measurement problem”. “Bohr’s view is still a type of relational holism, but an epistemic rather than ontological variant” (Teller 1989, Faye 1991, Dorato 2017).
§4: Bohr and dualisms
Objective reporting, for Bohr, “presumes those very dualisms that Barad claims Bohr questions”: we must speak as though object and subject (instrument and experimenter) are sharply separate. An experiment is “a situation where we can tell others what we have done and what we have learned” (Bohr 1949, 209), so “the knower/known dualism is where Bohr’s interpretation of quantum mechanics begins and ends”. Complementarity does restrict which classical concepts apply in which context, but “Words, world, and meaning are not co-produced. Rather, the classical terminology, adapted to our ordinary experiences, is given.” Conclusion: “If anything, these dualisms are at the foundation of Bohr’s interpretation.”
§5: agential realism and quantum mechanics
- Not entailed. Bohmian mechanics reproduces all of quantum mechanics’ predictions with “individual particles with determinate position and (instantaneous) velocity” and deterministic trajectories. It shares two features with agential realism (no ontological division between object and experiment; properties other than position produced in interaction) but its “interconnectedness” is “between individuals”. “At best, agential realism provides us with the epistemological and ontological implications of one particular interpretation.”
- Relational quantum mechanics is close but not the same. Rovelli (1996): no observer-independent values; “freedom in drawing the line” between system and observer, which is the cut “in Barad’s terminology”; an observer O cannot describe its own interaction with S, and an external P describes S+O as entangled. Barad’s answer (2007, 348) runs parallel. But Rovelli’s ontology is “a sparse ontology of (relational) quantum events happening at interactions between physical systems”, “which means, of course, that the systems precede the interactions”. RQM’s observer is “any physical system”; Barad’s measurement “involves leaving a mark on the measuring agency”.
- The measurement problem. For Barad the entanglement is never undone: “we should not conclude from the fact that the entanglement is not made explicit by this measurement that the entanglement has become ontologically ‘disentangled’” (2007, 348). RQM avoids collapse by treating the wave function as bookkeeping; agential realism cannot, since intra-actions produce determinate values while the systems stay ontologically entangled, and “the system ‘appears as a mixture if the degrees of freedom of the instruments are bracketed’” (2007, 346) “does not explain why a measurement finds one rather than another value”. Borrowing Rovelli’s solution “would compromise the ontological relational holism that drives many of the other alleged consequences”. “In the absence of such studies, even saying that agential realism is consistent with quantum mechanics involves a leap of faith.”
§6: conclusion
“Agential realism is not forced upon us by quantum mechanics.” “As social theorizing, Barad’s ideas are profound, interesting, and thought provoking and we have not argued here that agential realism is without any merits. We have only argued that, if any, these do not stem from quantum mechanics.”
Claims
| id | claim | strength | support |
|---|---|---|---|
| C1 | For Bohr a phenomenon is epistemic and derivative, object and instrument real | strong | Bohr’s own statements (1938, 1949) and the convergence of the secondary readings (§3) |
| C2 | Bohr was an entity realist on the majority reading, which defeats Barad’s holism | strong | Folse 1986, Faye 1991 (§3) |
| C3 | Bohr presupposes the subject–object, knower–known and word–world dualisms | moderate | interpretive argument from Bohr 1949, 209 (§4) |
| C4 | Quantum mechanics does not entail agential realism | strong | existence of Bohmian mechanics, an empirically equivalent interpretation with an individualist ontology (§5) |
| C5 | RQM differs from agential realism in keeping systems prior to interactions | moderate | Rovelli 2018 and Smerlak and Rovelli 2007, as quoted (§5) |
| C6 | Agential realism has no answer to the measurement problem, and its consistency with QM is unshown | moderate | argument from Barad 2007, 346–350; the authors allow “more subtle ways” may exist (§5) |
Concepts
- Phenomenon (Bohr) — the observation obtained under specific circumstances, including the whole experimental arrangement; epistemic.
- Phenomenon (Barad) — the ontological primitive: object and agencies of observation inseparable, relata emerging within it.
- Epistemic relational holism — quantum systems have classical properties only with respect to their interaction with an instrument, without the relata being dissolved (Teller, Faye, Dorato).
- Entity realism — experiments, especially manipulation, commit one to the entities manipulated (Hacking 1983; Cartwright 1983).
Connections
- Jaksland 2024 (LIT-1673, NOTE-1230), which assumes what this paper contests and asks what follows for metaphysical method.
- Rovelli (LIT-1635, unread; LIT-177, read): the reading makes the comparison the exchange’s A6 §5A summarized, and correctly.
- Pinch (2011), who noticed the Bohmian contrast and did not develop it.
Bearing on the record
- The exchange’s account of this paper was accurate. A4 §7B and A6 §5A gave three criticisms (Barad’s Bohr more ontological than Bohr; RQM not entailing her holism; an unresolved measurement problem) and the verdict “quantum mechanics does not force agential realism upon us. The authors even question whether its compatibility with quantum mechanics has been adequately established.” All four hold on the text. LIT-1672’s summary stands.
- CLAIM-476’s borrowing is right to stay out of physics. The claim borrows the apparatus without the interpretation and says so. The reading confirms the borrowing is the only one available without a leap of faith: what makes luria an apparatus cannot be agential realism’s quantum credentials. It also supplies Barad’s own statement of the apparatus, through the authors’ quotation (2007, 148): “the material conditions of possibility and impossibility of mattering; they enact what matters and what is excluded from mattering”. The dated note on the claim carries both.
- CLAIM-136 and CLAIM-477: Bohr is the non-eliminative relational holist, Barad the eliminative one. Bohr’s relational properties are relational properties of real relata, ”… is recorded to have position p in relation to …”, an epistemic relational holism. That is the shape of the record’s non-eliminative choice, and of CLAIM-477’s “partly fixed”. The record’s nearest physical precedent in this neighbourhood is Bohr as Faye and Jaksland read him, not Barad.
- CLAIM-150: a clean instance of its guard. “Compatible with quantum mechanics” against “entailed by” is CLAIM-150’s identification against constitution in another key: an empirically equivalent interpretation with intrinsically individuated particles reproduces the predictions, exactly CLAIM-150’s reason that “an ontology of intrinsically individuated objects with relational properties can reproduce the same predictions”. No note is filed; the claim’s grounds already make the point in general.
- TERM-087. The movable separation is Heisenberg’s against Bohr’s (a note to §2), which corrects the TERM’s line keeping the Heisenberg cut apart. Bohr’s own separation, on this reading, is fixed and epistemic, justified by the need for unambiguous classical description; whether that makes it a Cartesian cut in Barad’s sense is my question, not the authors’. The TERM is corrected in place.
Limitations
- Exegetical arguments about Bohr cannot settle what Barad’s view is worth on its own terms; the authors say so (§6) and grant that Barad may, like QBism, draw inspiration from Bohr without claiming his authority.
- The measurement-problem argument is a challenge, not a proof of incoherence; “There might be other more subtle ways to address the measurement problem within the framework of agential realism” (§5).
- Read from HTML without page numbers.