Ontological Evasions in Physics, Part 6 Quantum Bayesianism (QBism): Retreat into the Observer

Quantum mechanics repeatedly confronts physics with the tension between formalism and ontology. One response to this tension is Quantum Bayesianism, or QBism, which recasts the quantum state not as a property of a system, but as a reflection of an agent’s personal beliefs about possible outcomes.

At first glance, QBism appears to solve the measurement problem elegantly: collapse is nothing more than the updating of an observer’s probabilities. But beneath this apparent clarity lies a familiar ontological evasion.

The evasive manoeuvre

QBism relocates reality into the mind of the observer. The formalism is preserved, but at the cost of dissolving the system itself into an epistemic shadow. Outcomes are not actualised in the world; they are experiences registered by agents. The world becomes an extension of belief, not a domain of relational actuality.

This manoeuvre allows physicists to sidestep deep questions: What is the ontology of the quantum system? How does possibility actualise? Instead of addressing these issues, QBism effectively says: “Don’t worry about reality; focus on your expectations.”

The ontological cost

The world is no longer a network of relational events; it is a projection of subjective credences. Possibility and actualisation are flattened into the agent’s updates. Collective alignment, interaction, and emergent structure—the core of relational ontology—vanish from the picture. Reality is now dependent on consciousness, which means relationality is subordinated to belief.

The epistemic collapse

If outcomes exist only in the agent’s experience, then experiment no longer constrains reality; it constrains belief. Science risks becoming an internal bookkeeping exercise: probabilities adjusted in minds, rather than structures revealed in the world. Evidence cannot falsify or confirm theory in any robust sense, because it is inseparable from the observer’s prior expectations.

The theological return

As with other evasions, QBism smuggles in the theological impulse, albeit subtly. By placing the observer at the centre of actualisation, it effectively installs a local, personal “creator” for each measurement event. Each agent becomes a tiny deity, and the universe itself is fragmented into countless subjective realms.

A relational reframing

Relational ontology dissolves the paradox without retreating into subjectivity. Outcomes are actualised not in isolated observers, but through the collective alignment of relational construals. Possibility is not private; it emerges perspectivally across interacting systems. Measurement is a moment of relational actualisation, not the conjuring of reality by an agent’s mind.

By reframing the problem relationally, QBism’s retreat into subjectivity is unnecessary. One can preserve the predictive power of the formalism while keeping ontology intact. Possibility, actuality, and alignment remain real, but they are emergent and collective, not the product of isolated belief.

Conclusion

QBism exemplifies an evasion that preserves formalism by privatising reality. Measurement and collapse are recast as epistemic updates, but in doing so, physics abandons relational ontology. Relational thinking restores coherence: actuality emerges in relation, not in the mind, and science remains a probe into the world rather than a meditation on belief.

Ontological Evasions in Physics, Part 3 Wavefunction Collapse: Smuggling Mind into Matter

Quantum mechanics introduced the wavefunction: a mathematical object encoding the probabilities of different outcomes. The formalism is clear enough, but the question has always been: what does the wavefunction mean? What is it a description of?

The orthodox answer—the so-called Copenhagen interpretation—deploys one of physics’ most enduring evasions: wavefunction collapse.

The evasive manoeuvre

The story goes like this: the wavefunction evolves deterministically according to Schrödinger’s equation, until a measurement occurs. At that moment, the wavefunction “collapses” into a definite outcome. Before measurement: superposition. After measurement: actuality.

This picture offers physicists a convenient divide. Quantum weirdness on one side, classical certainty on the other. The catch is that the divide rests on a vague and unstable category: “measurement.” What counts as a measurement? Why should the cosmos care whether a device—or a human observer—is watching?

Here the evasion is clear. Instead of reconceiving causation and relation, physics projects the indeterminacy onto the observer, as if mind itself must intervene in order for matter to be real.

The ontological cost

Wavefunction collapse imports consciousness as an unacknowledged deus ex machina. Ontology is split into two domains: one governed by smooth mathematical evolution, the other punctuated by miraculous collapse. Reality is fractured into dual regimes, joined only by the mysterious agency of “measurement.”

This is not an explanation but a deferral: a refusal to confront what possibility and actuality mean in relation. By outsourcing the problem to “mind,” physics preserves its equations at the cost of ontological incoherence.

The epistemic collapse

Science depends on the reproducibility of observation. Yet if reality hinges on “measurement” in some undefined sense, the ground of scientific practice is eroded. Collapse theory implies that experimenters are not probing reality, but actively conjuring it into existence by their acts of observation. Inquiry then loses its neutrality and becomes an act of ontological magic.

The theological return

Again, the supposed hard-headed stance conceals theological traces. The collapse postulate reinstates a metaphysics of miracle: smooth order interrupted by sudden intervention. The observer becomes a priestly figure, mediating between potential and actual, a stand-in for divine agency.

A relational reframing

From a relational perspective, the puzzle dissolves. The wavefunction is not a ghostly object waiting for collapse, but a construal of perspectival potential. Measurement is not an ontological rupture but a perspectival alignment: the actualisation of relation between system and context. Possibility does not end in collapse; it unfolds into new individuations.

The real lesson of quantum mechanics is not that mind conjures matter, but that actuality is always perspectival: emergent from relational construal, not from a hidden dualism.

Conclusion

Wavefunction collapse is physics’ way of smuggling mind into matter while pretending to keep ontology clean. By placing the burden on “measurement,” it evades the deeper question of how possibility actualises within relation.

The alternative is to abandon the collapse story altogether: not mind intervening in matter, but relation unfolding into actuality without need for miracles or evasions.