Von Neumann’s Measurement Chain without Dualism

Subjective Perception as the Natural Endpoint under Phenomenological Absolutism and Mutual Exclusivity

Author: Patrick David Aoun

Date: August 29, 2026

Abstract

Von Neumann’s 1932 analysis of the quantum measurement chain establishes that unitary evolution can be extended through any physical apparatus or the observer’s body, and that the formalism supplies no intrinsic criterion for locating a non-unitary cut. The later rejection of placing that terminus at subjective perception did not follow from a defect in the chain argument. It followed from a physicalist ontology that treats mind and world as ontologically distinct—an assumption the mathematics of quantum mechanics does not require. Under Phenomenological Absolutism and Mutual Exclusivity, each localized actualized field configuration is identical with the absolute is-ness of first-person phenomenology. On that ontology the endpoint is not an extra-physical intervention in a closed material chain. It is what an actualized configuration already is. We reconstruct von Neumann’s position with textual fidelity, distinguish it from later causal claims that consciousness collapses the state, and show that the dualistic objections lose their force once the extraneous metaphysical premise is withdrawn. The mathematics remains compatible with other interpretations. Our claim is that von Neumann’s conclusion fits naturally when the ontology does not smuggle in a subject–object split the theory itself never licensed.

I. Introduction

Quantum mechanics, as formulated by von Neumann, contains two modes of state change. Process 2 is the continuous, reversible, unitary evolution generated by the Schrödinger equation. Process 1 is the discontinuous, irreversible change associated with measurement: the state is replaced by an eigenstate of the measured observable, with probabilities given by the Born rule (von Neumann, 1955, 2018). The tension between these processes is the measurement problem in its canonical form. If the theory is universal, the measuring apparatus is itself a quantum system, and the interaction between object and apparatus is a Process 2 coupling. The joint state then becomes an entangled superposition. The same reasoning applies to any further physical link—a second apparatus, a recording device, a retina, an optic nerve, a cortical assembly. Nothing in the Hilbert-space formalism marks a privileged physical stage at which Process 1 must replace Process 2. This sequence is the von Neumann chain.

Von Neumann drew the consequence with characteristic clarity. The cut that separates the observed system from the observer can be displaced arbitrarily far along the chain without altering the predicted statistics. Experience, however, does not report that “a physical quantity has a certain value.” It reports that “an observer has made a certain (subjective) observation.” Measurement, or the related process of subjective perception, is therefore “a new entity relative to the physical environment and is not reducible to the latter” (von Neumann, 1955). The principle of psycho-physical parallelism requires that this extra-physical process be describable as if it corresponded to physical processes in ordinary space, which is why the cut remains movable. It does not cancel the fact that, however far the physical description is pushed, one must at some point say: and this is perceived by the observer (von Neumann, 1955, 2018).

The formal analysis has never been the principal target of criticism. The mathematics of the chain is correct. What was rejected is the natural terminus of the argument: that the description bottoms out in subjective perception. Under the physicalist ontology that became the default metaphysics of twentieth-century physics, that terminus looks like a dualistic intervention. A non-physical mind is asked to interrupt an otherwise closed material process. The charge of mysticism, the worry about causal overdetermination, and the complaint that consciousness is undefined as a physical variable all follow from that ontology. They do not follow from the chain argument itself. Quantum mechanics does not encode physicalism. Physicalism is an extra premise.

We withdraw that premise and replace it with Phenomenological Absolutism and Mutual Exclusivity (PA/ME) (Aoun, 2025, 2026a). On that ontology the sole actualized reality consists of localized, mutually exclusive field configurations. Each such configuration is an absolute is-ness, identical with the complete first-person phenomenology of that moment. There is no ontic gap between the actualized physics and the experience. Consciousness is not a second substance and not a causal agent acting on matter. It is the is-ness of the actualized configuration. Under that identification, von Neumann’s endpoint is not an anomaly. It is what an actualized configuration already is.

Two clarifications fix the scope of the paper. First, we do not attribute to von Neumann the later thesis, associated especially with Wigner, that consciousness causally collapses the wave function (Wigner, 1961; Chalmers & McQueen, 2022; Laudisa, 2025). The 1932 text is more cautious: it locates the terminus of the chain at subjective perception and insists on the mobility of the cut; it does not supply a dynamical law in which mind acts on the state vector. Second, we do not claim that PA/ME is the only viable ontology, that it derives the Born rule as a selection dynamics, or that it dissolves every version of the measurement problem. The mathematics remains compatible with other interpretations. Our claim is stricter and sufficient: once the dualism that physicalism imports is removed, von Neumann’s conclusion is no longer philosophically illegitimate. It is the expected terminus of a universal quantum description.

The paper proceeds as follows. Section II reconstructs the chain analysis and the relevant passages of Chapter VI of Mathematical Foundations of Quantum Mechanics (von Neumann, 1955, 2018). Section III isolates the physicalist premises that converted a formal result into an unacceptable metaphysics. Section IV states the tenets of PA/ME required for the mapping (Aoun, 2025). Section V carries out that mapping. Section VI answers the principal objections and states the limits of the argument. Section VII concludes.

II. Von Neumann’s Chain Analysis: Formal Reconstruction

A. Two Processes

In Chapter VI of Mathematical Foundations of Quantum Mechanics, von Neumann distinguishes two changes of state. Process 2 is the unitary evolution of the Schrödinger equation: continuous, deterministic, and reversible. Process 1 is the change associated with measurement: the state is replaced by an eigenstate (or by the corresponding mixture, in the ensemble formulation), discontinuously and irreversibly, with probabilities given by the Born rule (von Neumann, 1955, 2018). If quantum mechanics is a universal theory, every physical interaction—including the coupling of an object to an apparatus—is a candidate for Process 2. The joint state of object and apparatus is then an entangled superposition. Definite pointer readings do not appear in that description. Process 1 must be introduced by hand if the theory is to report a single outcome.

The problem is not that Process 1 is formally undefined. Projectors and the trace rule are precise. The problem is that the theory does not say, in physical terms, when Process 1 applies. “Measurement” is not a predicate internal to the Hilbert-space formalism. It is an extra-theoretic label.

B. The Chain and the Movable Cut

Von Neumann’s response is the chain. Let I be the object, II an apparatus, and III the remainder of the observer. The interaction of I with II can be treated as Process 2. The composite I+II then stands to III as object to observer, and Process 1 may be applied at that interface. Equally, I+II+III may be treated unitarily until a still later interface. The predicted statistics for the final observation are invariant under this displacement. The Heisenberg cut is therefore movable. There is no privileged physical stage—mercury column, scale, photon, retina, optic nerve, or cortical assembly—at which the formalism itself demands a break with unitarity (von Neumann, 1955).

The thermometer example makes the point concrete. One may treat the temperature of a fluid as measured by the height of a mercury column; or treat the column as measured by a beam of light; or treat the light as measured by the retina; or push the cut into the optic nerve and beyond. At each stage the quantum description of the preceding links remains consistent with the same observational statistics. “However far we calculate—to the mercury vessel, to the scale of the thermometer, to the retina, or into the brain—at some time we must say: and this is perceived by the observer” (von Neumann, 1955). The chain can be lengthened without bound on the physical side. It cannot be lengthened without bound if a comparison with experience is to remain possible.

C. Subjective Perception and Psycho-Physical Parallelism

Von Neumann does not treat this terminus as a mere convenience. He writes that it is “inherently correct that measurement or the related process of subjective perception is a new entity relative to the physical environment, and is not reducible to the latter.” Subjective perception “leads us into the intellectual inner life of the individual, which is extra-observational by its very nature, since it must be taken for granted by any conceivable observation or experiment.” Experience, he adds, “only makes statements of this type: an observer has made a certain (subjective) observation; and never like this: a physical quantity has a certain value” (von Neumann, 1955).

The scientific requirement that accompanies this claim is the principle of psycho-physical parallelism: it must be possible to describe the extra-physical process of subjective perception as if it were in the physical world—to assign to its parts equivalent physical processes in ordinary space (von Neumann, 1955, 2018). That principle is what licenses the mobility of the cut. It does not cancel the distinction on which the mobility rests. If the boundary were not placed somewhere, the principle would be vacuous: there would be no observation with which the physical description could be compared. The world must be divided into an observed part and an observer. The location of the division is largely arbitrary. The necessity of a division is not.

D. What von Neumann Did Not Claim

Two later readings must be kept apart from this text. First, von Neumann does not argue that consciousness is a dynamical cause that acts on the state vector at a definite instant and produces collapse as a physical force. He identifies the terminus of the chain with subjective perception and insists that perception is not reducible to the physical environment. He does not write down a modified Schrödinger equation in which a mental variable appears (Laudisa, 2025). Second, he does not claim that the cut is immovable once it reaches a human mind. On the contrary, the cut remains displaceable, including into the interior of the observer’s body. What cannot be eliminated is the fact of perception as the point of contact with experience.

Recent historiography has emphasized this caution. The radical thesis that consciousness causally collapses the state is more properly associated with later writers, above all Wigner, than with the 1932 monograph (Wigner, 1961; London & Bauer, 1939; Laudisa, 2025). Our reconstruction follows the monograph. The formal result we take as established is this: if quantum mechanics applies to every physical system, the chain has no physical last link; the last link in any account that can be compared with experience is subjective perception.

III. The Metaphysical Source of the Rejection

A. What Was Accepted and What Was Not

The formal content of the chain analysis was not the main object of attack. That unitary evolution can absorb any given apparatus, that the cut can be moved without changing the statistics, and that no Hamiltonian criterion marks a last physical link—these points have been repeated, refined, and used as the starting point of later work on measurement, decoherence, and Wigner’s-friend scenarios (Zeh, 1970; Zurek, 2003; Barrett, 1999). What was refused is the terminus von Neumann assigned to the chain: subjective perception as a process not reducible to the physical environment. The refusal is not a theorem. It is a metaphysical verdict.

B. Physicalism as an Extra Premise

By the mid-twentieth century the working ontology of most physicists was physicalism: whatever exists in the causal order is physical, or is exhausted by the physical, and the physical domain is causally closed. On that premise a terminus at perception looks like a breach. Either perception is itself a physical process, in which case it belongs inside the chain and cannot stop it, or it is not physical, in which case it is asked to do work—selecting a definite outcome—that no physical process is permitted to do. Dualism, causal overdetermination, and conflict with closure follow at once. Consciousness, under the same premise, is at best an emergent epiphenomenon and at worst an undefined variable. It cannot be the last link of a fundamental theory (Chalmers, 1996).

None of this is written into the Hilbert-space formalism. Quantum mechanics supplies amplitudes, operators, and two modes of state change. It does not state that the ontic inventory is exhausted by spacetime fields and their excitations, nor that first-person phenomenology is a late product of those fields. Physicalism is imported. Once imported, von Neumann’s endpoint is recoded as an illicit mind–matter interaction. The recoding is then offered as a reason to reject the endpoint. The circle is tight and uninformative: the conclusion is unacceptable because it violates an ontology the mathematics never required.

C. How the Charge of Mysticism Was Produced

Wigner’s 1961 “Remarks on the Mind-Body Question” tightened the later folklore. Wigner treated the superposition of a friend’s conscious states as absurd and inferred that consciousness must play a distinguished role in collapse (Wigner, 1961). That inference is stronger than von Neumann’s text. It also made the target easier to attack. Putnam, Shimony, and others objected that consciousness is ill-defined as a physical magnitude, that the view is dualistic, and that it threatens objectivity (Putnam, 1961; Shimony, 1963). Wigner himself later withdrew the claim. The stronger causal thesis then became less attractive as discussions of decoherence and macroscopic quantum theory relocated the cut without invoking consciousness (Zeh, 1970; Zurek, 2003). That later shift is often read as a scientific refutation of von Neumann. It is better read as a retreat from a stronger thesis than von Neumann had advanced, under pressure from an ontology that had already decided what a respectable last link could be (Laudisa, 2025).

Decoherence then appeared to complete the eviction. Environment-induced suppression of interference explains why macroscopic pointer states are robust and why a reduced density operator looks classical (Zeh, 1970; Zurek, 2003). It does not select a single outcome, and it does not replace Process 1 with a derived dynamical law. It relocates the cut. The remaining definite-outcome problem is then declared pragmatic, or is absorbed into many-worlds, relational, or QBist accounts (Barrett, 1999). In each case the work that von Neumann assigned to perception is reassigned so that nothing extra-physical remains. The reassignment is again driven by the demand that the ontology stay physicalist, not by a demonstration that the chain analysis was formally wrong.

D. The Empirical Profile of the Rejection

Interpretation surveys confirm the pattern. At a 2011 foundations meeting, only a small fraction of respondents assigned the observer a distinguished physical role such as consciousness-induced collapse (Schlosshauer, Kofler, & Zeilinger, 2013). Larger later discussions continue to treat consciousness-collapse as a minority option (Chalmers & McQueen, 2022). That distribution is not a measurement of the chain argument’s validity. It is a measurement of what the community will tolerate given its background metaphysics. A conclusion that requires first-person phenomenology to be more than an optional commentary on a closed physical process will be counted as unacceptable for that reason alone.

The historiographical correction is therefore simple. Von Neumann showed that a universal quantum theory has no physical last link. Physicalism forbids a non-physical last link. The conjunction yields rejection. Remove the second premise and the rejection loses its ground. The next sections state an ontology in which the first-person terminus is not a second substance acting on matter, and then return the chain to that setting.

IV. Phenomenological Absolutism and Mutual Exclusivity: A Minimal Sketch

A. Purpose of the Sketch

We do not argue here that PA/ME is the only coherent ontology, nor do we re-derive it from first principles. We state the tenets required to relocate von Neumann’s terminus. The relevant commitments are three: localized actualization, mutual exclusivity, and the identity of the actualized configuration with first-person phenomenology (Aoun, 2025, 2026a, 2026e).

B. Localized Actualization

Relativistic quantum field theory, read with ontological austerity, does not license a single globally actualized field configuration across a spacelike hypersurface (Peskin & Schroeder, 1995; Haag, 1996). What is actualized is local. Algebraic formulations make the point sharp: observables are tied to spacetime regions; states are restrictions of a global algebraic state to local algebras; frame-dependent simultaneity forbids a privileged “now” in which the entire universe is actual together (Einstein, 1961; Haag, 1996; Aoun, 2026e). The austere conclusion is that the ontic inventory, at any account of what is actual, consists of a localized field configuration—not a completed block universe and not a persisting global wave function waiting to be inspected. Stitching these localized actualizations into a single, coexisting objective manifold would require an external, trans-spacetime coordinate system—a “God’s-eye” view that relativistic physics explicitly denies. Mutual exclusivity simply takes this denial at its ontological word (Aoun, 2026a, 2026d).

C. Mutual Exclusivity

If only localized configurations are actualized, and if actualization is not indexed from a trans-configuration vantage point, then distinct actualizations do not coexist in a common ontic manifold. Each actualized configuration is exclusive of the others. There is no substrate that houses many realizations at once, no meta-time in which they are sequential parts of one object, and no external standpoint from which they can be counted as simultaneous alternatives (Aoun, 2025, 2026c). Talk of succession, memory, and causal linkage is not banned. It is relocated: such talk is a configuration within an is-ness, not a relation between is-nesses. The demand for a trans-realization glue is the demand that reopens infinite regress.

D. Phenomenological Absolutism

Phenomenological Absolutism identifies each exclusive actualized configuration with the absolute is-ness of first-person phenomenology (Aoun, 2025, 2026a, 2026b). The configuration is not a hidden physical base that produces experience as a later effect. It is not a mental representation of an independent world. Ontic structure and epistemic structure coincide locally: what is actualized is the complete experiential reality of that moment. Traditional physicalism posits a mindless, unexperienced material substrate that we can only ever indirectly infer. Phenomenological Absolutism applies strict ontological parsimony by collapsing that redundant, invisible substrate into the actualized configuration that is the evidence. Consciousness is therefore not an entity, not a substance, and not a causal agent standing over against physics. It is the is-ness of the actualized configuration.

This identity dissolves the gap that physicalism inserts between “subjective” and “objective.” There are not two realms to be bridged. There is one exclusive actuality, describable in the vocabulary of local field configurations and lived as phenomenology. Scientific descriptors—Hamiltonians, density operators, pointer readings—remain available. They function as internal articulations of the is-ness, not as reports on a residual world behind it (Aoun, 2025; French, 2002).

E. What Follows for Measurement

Three consequences matter for the chain. First, there is no ontic series of coexisting physical systems jointly occupying a superposition that must be broken by an outside mind. Only one exclusive is-ness is actual. Second, definite outcome is not an extra event added to physics. It is the actualized configuration itself. Third, the “observer” is not a second substance at the end of a material pipeline. The observer-language of von Neumann names the fact that comparison with experience is comparison with is-ness. Section V applies these consequences to the chain.

V. Mapping the Chain onto PA/ME

A. What the Mapping Must Show

The mapping is successful if three conditions hold. The formal results of Section II remain intact: unitary descriptions can still be written for object, apparatus, and organism; the cut remains displaceable in the theory’s internal bookkeeping; the statistics of Process 1 are unchanged (von Neumann, 1955). The dualistic reading of Section III is no longer forced: nothing extra-physical acts on a closed material world. The terminus von Neumann named—subjective perception—coincides with what PA/ME already takes as actual: the exclusive is-ness of a localized configuration (Aoun, 2025, 2026b).

B. Unitary Descriptions as Internal Configurations

Process 2 does not disappear. A coupling Hamiltonian between object and apparatus, an entangled state on a tensor-product space, a further coupling to a recording device or to neural degrees of freedom—all of these remain legitimate descriptions (von Neumann, 1955; Kandel et al., 2013). Under PA/ME they are not photographs of a persisting trans-moment substrate. They are articulations available within an is-ness. One can acknowledge, in the present configuration, a narrative of interaction, entanglement, and amplification. That acknowledgment is itself the is-ness in which the narrative appears. Extending the quantum description “into the brain” is therefore not the discovery of a last physical object still awaiting collapse. It is the construction, inside the actualized phenomenology, of a more inclusive physical model of the same exclusive moment (Aoun, 2025).

The mobility of the cut receives the same reading. Von Neumann showed that predicted observation statistics do not depend on where, along a physical sequence, Process 1 is written down (von Neumann, 1955). PA/ME agrees, because those alternative writings are alternative internal bookkeepings, not alternative ontic histories competing in a common manifold. The cut is movable because it was never the scar of an interaction between two substances. It marks the point at which a given account stops modeling and stands as the is-ness it already is.

C. Why There Is No Ontic Regress

The regress that troubles physicalism is this: every physical link can be absorbed into Process 2, so the superposition never ends. That regress presupposes a single ongoing physical world in which all links coexist and remain superposed until an outside factor intervenes. Mutual exclusivity denies the presupposition (Aoun, 2025, 2026c). There are not coexisting links waiting in a shared Hilbert space for a cut. There is one actualized configuration. The “unresolved chain” is a description one can write; it is not an ontic remainder sitting behind the is-ness. An unresolved cut, in the sense of Section I, does not mean that a particle has failed to come into being. The field degrees of freedom are not missing. What is not present, if one insists on the language of definite eigenvalues, is a classical value as a trans-phenomenological fact. Under PA/ME that value is not an extra fact. When the configuration is the experience of a definite pointer reading, the definite outcome is the is-ness.

D. Perception without Intervention

Von Neumann’s sentence—“and this is perceived by the observer”—is then exact rather than embarrassing (von Neumann, 1955). Perception is not a mind colliding with matter. It is the absolute character of the actualized configuration. The extra-physical status he assigned to subjective perception is preserved in one respect and canceled in another. It is preserved insofar as perception is not reducible to a list of objects standing over against an inner life: the is-ness is not a bundle of independent things plus an added witness. It is canceled insofar as there is no second realm that must reach into physics to finish a job physics cannot finish. Psycho-physical parallelism, on this reading, is the requirement that the is-ness be articulable in physical vocabulary—local operators, pointer observables, neural correlates—without remainder and without a hidden base (von Neumann, 1955; French, 2002; Aoun, 2026e). The parallelism is not a bridge. It is the two-sided intelligibility of one exclusive actuality.

E. Collapse, Detectors, and Is-ness

We do not identify every physical talk of collapse with is-ness. A detector click can be modeled as a localized irreversible amplification without anyone’s later commentary. Under PA/ME that model is an acknowledgment available in some is-ness; it is not a proof that a second, mindless world actualizes outcomes on its own and only later becomes experience. Conversely, we do not say that a superposition persists in a hidden warehouse until a consciousness inspects it. There is no warehouse. The language of persistence and inspection belongs to the continuity metaphysics already rejected (Aoun, 2025). What von Neumann needed was a last point of contact with experience. PA/ME supplies that point without installing a causal ego. The last point is not reached by travel along a chain. It is the actuality in which any such chain-description can appear.

F. Born-Rule Regularities

The mapping does not derive the Born rule as a stochastic jump between exclusive is-nesses. That derivation would reintroduce a trans-is-ness dynamics. Frequencies, amplitudes, and the reliability of “this pointer, not that one” appear as law-like regularities internal to configurations—the way energetic and attentive structure hangs together in the is-ness that includes experimental practice (Aoun, 2025, 2026f). The rule remains the correct bookkeeping for Process 1 (von Neumann, 1955). Its ontological status is the same as that of other acknowledged regularities: present, coherent, not the trace of a glue between mutually exclusive actualizations.

The result of the mapping can be stated in one line. Von Neumann’s chain is the correct analysis of a universal quantum description. PA/ME is the ontology in which that analysis no longer ends in a dualistic scandal. The endpoint is first-person phenomenology because first-person phenomenology is the actualized configuration (Aoun, 2025, 2026b).

VI. Scope, Limits, and Anticipated Objections

A. What This Paper Does Not Claim

The mathematics of quantum mechanics remains compatible with other interpretations. Decoherence-based accounts, relational quantum mechanics, certain Copenhagen variants, QBism, and Everettian views can all absorb the formal mobility of the cut (Zeh, 1970; Zurek, 2003; Barrett, 1999). We do not argue that PA/ME is uniquely selected by von Neumann’s calculations, that it supplies a new empirical prediction, or that it replaces Process 1 with a derived dynamical law. We do not derive the Born rule from a transition between exclusive is-nesses. We do not claim to have solved every formulation of the measurement problem. The thesis is narrower and sufficient: the standard grounds for calling von Neumann’s terminus unacceptable rest on a physicalist dualism the formalism does not entail; under PA/ME that terminus is the expected identity of actualized configuration and phenomenology.

B. Solipsism

The objection that exclusive is-nesses collapse into solipsism confuses ontic exclusivity with the denial of other phenomenology. Solipsism asserts a privileged, persisting self as the only existent. PA/ME denies a persisting self and denies a trans-is-ness inventory in which selves could be ranked (Aoun, 2025). Another person’s speaking is not ontically packed into one’s hearing; each is an exclusive actuality. The acknowledgment of “conversation,” “agreement,” or “shared data” is a configuration within an is-ness, not a passport to a common substrate. That is not the claim that only one mind exists. It is the claim that existence is not a warehouse of co-present minds. Intersubjective practice—calibration, replication, citation—survives as phenomenological coherence, which is the only form in which it was ever encountered. When two physicists agree on a detector click, this is not two separate minds making contact in a third, unseen physical space. Rather, the “shared agreement” and the presence of the colleague are structurally stable, law-like features entirely actualized within the exclusive is-ness of that moment.

C. Continuity, Memory, and Experiment

If moments are exclusive, how can a laboratory protocol, a stored sample, or a remembered pointer reading remain reliable? The question assumes that reliability requires an ontic thread connecting earlier and later realizations. PA/ME treats reliability as a present configuration: memory is instantiated now; the protocol is acknowledged now; the sample-as-prepared is a feature of this is-ness, not a surviving fragment of a previous world (Aoun, 2025; Kandel et al., 2013). The objection that this makes planning or repetition impossible mistakes a linguistic tense for an ontology. One plans, repeats, and publishes inside the is-ness in which those acts are actual. The success of experimental science is not evidence of a hidden manifold. It is evidence that configurations appear to include stable, law-like structure.

D. Decoherence and Preferred Bases

Decoherence explains the dynamical fragility of macroscopic superpositions and the emergence of robust pointer records in the reduced description of a system plus environment (Zeh, 1970; Zurek, 2003). It does not, by itself, yield a single experienced outcome. Relocating the cut to an environment-system boundary therefore leaves von Neumann’s problem intact unless one already accepts an ontology in which reduced states or branching records are enough. PA/ME does not compete with the calculations of decoherence. It refuses the further inference that those calculations evict phenomenology from the terminus of the account. A decohered pointer state is still a description. The is-ness is the actuality in which that description, or the look of the pointer, obtains.

E. Wigner’s Friend and Extended Scenarios

Extended Wigner’s-friend arguments probe the consistency of assigning definite outcomes inside a laboratory while an external agent still writes a superposition of the laboratory (Wigner, 1961; Barrett, 1999). Under physicalism those arguments force a choice among anti-realism about outcomes, limits on universality, or many-worlds branching. Under PA/ME the apparent conflict is the demand that two exclusive is-nesses—the friend’s and Wigner’s—be jointly actual in one manifold so that their assignments can contradict each other as ontic facts. They are not jointly actual. Each assignment is the content of an exclusive configuration (Aoun, 2025, 2026c). The thought experiment remains useful as a stress test of bookkeeping. It does not reopen a shared stage on which two phenomenologies must be superposed.

F. Testability and Falsifiability

PA/ME is not a rival Hamiltonian. It will not be confirmed by a new fringe visibility or refuted by a Bell inequality. Its empirical contact is indirect: alignment with localized actualization in relativistic QFT, with the absence of a global simultaneous now, and with the discrete, modular character of neural and quantum processes as they appear in experience (Haag, 1996; Einstein, 1961; Kandel et al., 2013; Aoun, 2026e). A demonstration that a completed, mind-independent global configuration is actual independently of any is-ness would contradict the framework—but that demonstration would have to be given from a standpoint the framework says is unavailable. This is a limit, not a hidden escape. The same limit attaches to any ontology that takes first-person actuality as basic. The relevant question is whether the ontology removes a contradiction the default view cannot remove. We have argued that it does so for von Neumann’s terminus.

G. Dissolution and Explanation

A final objection says that identifying configuration with is-ness dissolves the problem instead of explaining how one outcome is selected. The objection is correct about the form of the result and wrong about what the chain required. Von Neumann did not supply a selection dynamics either (von Neumann, 1955; Laudisa, 2025). He supplied a terminus for a universal description that can meet experience. Physicalism made that terminus look like an unfinished mechanism. PA/ME makes it look like the identity it is. If one insists that only a trans-is-ness stochastic process counts as an answer, one has restated physicalist continuity as a criterion of adequacy. That criterion is what this paper declines.

VII. Conclusion

Von Neumann’s chain analysis stands. If quantum mechanics is universal, every physical link can be written under Process 2. The formalism does not nominate a last apparatus, a last neuron, or a last spacetime region at which unitarity must fail (von Neumann, 1955, 2018). A description that can be compared with experience still has to end. Von Neumann ended it at subjective perception: a process he judged new relative to the physical environment, extra-observational, and unavoidable if statements of the form “an observer has observed” are to remain the data of science. The principle of psycho-physical parallelism keeps the cut movable. It does not erase the terminus.

The later verdict that this terminus is unacceptable was not extracted from the mathematics. It was imposed by physicalism. That ontology treats first-person phenomenology as either a physical process still inside the chain or a non-physical intruder forbidden to finish the chain. Dualism, overdetermination, and the charge of mysticism are products of that fork. They are not products of Hilbert space (Wigner, 1961; Chalmers & McQueen, 2022; Laudisa, 2025).

PA/ME withdraws the fork. Localized actualization, mutual exclusivity, and phenomenological absolutism identify the actualized field configuration with the absolute is-ness of experience (Aoun, 2025, 2026a, 2026b). There is no second substance to intervene and no residual world in which a superposition waits. The unitary bookkeeping of the chain remains available as an internal articulation of the is-ness. The definite outcome is not delivered to phenomenology from elsewhere. It is the is-ness.

We have not claimed that this identity is the only coherent reading of quantum theory, that it computes the Born rule as a jump between realizations, or that it closes every debate that travels under the name of the measurement problem. We have claimed that von Neumann’s conclusion is the correct terminus of his own analysis, and that it looks illegitimate only while an ontology alien to the formalism is treated as obligatory. Change the ontology and the terminus is no longer an embarrassment. It is what an actualized configuration already is.

References

Aoun, P. D. (2025). Mutual exclusivity: A new compass for reality. Independently published. https://www.mutual-exclusivity.com

Aoun, P. D. (2026a). Phenomenological absolutism as the endpoint of austere physical realism. PhilArchive. https://philarchive.org/rec/AOUPAA

Aoun, P. D. (2026b). From zombie conceivability to phenomenological absolutism: Reframing the hard problem under localized actualization in QFT and relativity. PhilArchive. https://philarchive.org/rec/AOUFZC

Aoun, P. D. (2026c). Phenomenological absolutism, mutual exclusivity, and the dissolution of the free will problem. PhilArchive. https://philarchive.org/rec/AOUPAM

Aoun, P. D. (2026d). Why is there something rather than nothing? A dissolution under mutual exclusivity, phenomenological absolutism, and austere relativistic quantum field theory. PhilArchive. https://philarchive.org/rec/AOUWIT

Aoun, P. D. (2026e). Localized actualization in algebraic quantum field theory. PhilArchive. https://philarchive.org/rec/AOULAI

Aoun, P. D. (2026f). Chaos as ontic indeterminism: Epistemic limits as ontic structure in phenomenological absolutism and mutual exclusivity. PhilArchive. https://philarchive.org/rec/AOUCAO

Barrett, J. A. (1999). The quantum mechanics of minds and worlds. Oxford University Press.

Chalmers, D. J. (1996). The conscious mind: In search of a fundamental theory. Oxford University Press.

Chalmers, D. J., & McQueen, K. J. (2022). Consciousness and the collapse of the wave function. In S. Gao (Ed.), Consciousness and quantum mechanics (pp. 11–63). Oxford University Press.

Einstein, A. (1961). Relativity: The special and the general theory (R. W. Lawson, Trans.). Crown. (Original German work published 1916–1917)

French, S. (2002). A phenomenological solution to the measurement problem? Husserl and the foundations of quantum mechanics. Studies in History and Philosophy of Modern Physics, 33(3), 467–491. https://doi.org/10.1016/S1355-2198(02)00019-9

Haag, R. (1996). Local quantum physics: Fields, particles, algebras (2nd ed.). Springer.

Kandel, E. R., Schwartz, J. H., Jessell, T. M., Siegelbaum, S. A., & Hudspeth, A. J. (Eds.). (2013). Principles of neural science (5th ed.). McGraw-Hill.

Laudisa, F. (2025). Between myth and history: von Neumann on consciousness in quantum mechanics. Studies in History and Philosophy of Science, 114, Article 102083. https://doi.org/10.1016/j.shpsa.2025.102083

London, F., & Bauer, E. (1939). La théorie de l’observation en mécanique quantique. Hermann.

Peskin, M. E., & Schroeder, D. V. (1995). An introduction to quantum field theory. Addison-Wesley.

Putnam, H. (1961). Comments on the paper of David Sharp. Philosophy of Science, 28(3), 234–237. https://doi.org/10.1086/287807

Schlosshauer, M., Kofler, J., & Zeilinger, A. (2013). A snapshot of foundational attitudes toward quantum mechanics. Studies in History and Philosophy of Modern Physics, 44(3), 222–230. https://doi.org/10.1016/j.shpsb.2013.04.004

Shimony, A. (1963). Role of the observer in quantum theory. American Journal of Physics, 31(10), 755–773. https://doi.org/10.1119/1.1969073

von Neumann, J. (1932). Mathematische Grundlagen der Quantenmechanik. Springer.

von Neumann, J. (1955). Mathematical foundations of quantum mechanics (R. T. Beyer, Trans.). Princeton University Press.

von Neumann, J. (2018). Mathematical foundations of quantum mechanics (New ed.; R. T. Beyer, Trans.; N. A. Wheeler, Ed.). Princeton University Press.

Wigner, E. P. (1961). Remarks on the mind-body question. In I. J. Good (Ed.), The scientist speculates (pp. 284–302). Heinemann.

Zeh, H. D. (1970). On the interpretation of measurement in quantum theory. Foundations of Physics, 1(1), 69–76. https://doi.org/10.1007/BF00708656

Zurek, W. H. (2003). Decoherence, einselection, and the quantum origins of the classical. Reviews of Modern Physics, 75(3), 715–775. https://doi.org/10.1103/RevModPhys.75.715