Mark Stuckey 22 October 2025

In this article, Allori argues for treating quantum mechanics (QM) as a “constructive theory” per Einstein. Here is how Allori describes a constructive theory in “Many-Worlds: Why Is It Not the Consensus?” Quantum Rep. 2023, 5(1), 80-101:

"Some theories are what Einstein [3] called constructive theories. For one thing, these theories have a microscopic ontology, which constitute the building blocks of everything else. Constructive theories allow one to understand the phenomena compositionally and dynamically: macroscopic objects are composed of microscopic particles, and the macroscopic behavior is completely specified in terms of the microscopic dynamics. … by definition, constructive theories involve dynamical reductions in macroscopic objects in terms of the motion and interactions of their microscopic three-dimensional constituents. Therefore, the type of explanation these theories provide is bottom-up, rather than top-down."

Another way to describe this kind of theory is from Maltrana et al. ("Einstein’s Theory of Theories and Mechanicism," International Studies in the Philosophy of Science, 35(2), 153–170):

"Those theories that allow us to trace the causal mechanisms that explain mechanistically the occurrence of a certain phenomenon we call 'mechanistic theories'."

Trying to understand QM as a constructive theory leads inexorably to her conclusion that QM violates locality (implies “spooky actions at a distance,” e.g., Bohmian mechanics) or statistical independence (e.g., superdeterminism or retrocausality) or intersubjective agreement (e.g., QMism) or the uniqueness of experimental outcomes (e.g., Many-Worlds). However, there is another way to view QM that violates none of those things. This was recently shown by quantum information theorists who rendered QM a “principle theory” by reconstructing its Hilbert space kinematics via information-theoretic principles. Here is how Allori describes principle theories per Einstein (cited above):

"Principle theories are formulated in terms of principles, which are used as constraints on physically possible processes: they exclude certain processes from physically happening. In this sense, principle theories are top-down: they explain the phenomena identifying constraints the phenomena need to obey. They are 'kinematic' theories because the explanations they provide do not involve dynamical equations of motion and they do not depend on the interactions the system enters into."

And here is how Maltrana et al. describe such theories (cited above):

"those theories that lack agents whose actions are causally responsible for phenomena, but that instead provide general constraints or structural elements that lead to unificationist explanations we call 'structural theories'."

The unification achieved by the quantum reconstruction program is (perhaps surprisingly) between the Minkowski space kinematics (per the Lorentz transformations) of special relativity and the Hilbert space kinematics of QM by showing how both are based on the relativity principle (see “Unifying Special Relativity and Quantum Mechanics via Adynamical Global Constraints,” J. Phys.: Conf. Ser. 2948, 012009 (2025), open access). Here is a brief summary.

Instead of finding a causal mechanism for the empirically discovered fact that everyone measures the same value for the speed of light c, regardless of their motion relative to the source (observer-independence of the speed of light c aka the light postulate), Einstein said it had to follow from the relativity principle (the laws of physics are the same in all inertial reference frames aka “no preferred reference frame” NPRF). That is, since c is a constant of Nature according to Maxwell's electromagnetism, the relativity principle says c must be the same in all inertial reference frames. And, since inertial reference frames are related by uniform relative motions (boosts), the relativity principle tells us the light postulate must obtain. So, special relativity is a principle theory because its kinematics (Lorentz transformations) follows from an empirically discovered fact (the light postulate). And, importantly, the light postulate is justified by the relativity principle making it a principle explanation.

Given this “historical precedent” Carlo Rovelli suggested using principles of information theory to render QM a principle theory and in 2001, Lucien Hardy produced the first so-called reconstruction of QM via information-theoretic principles. The empirically discovered fact that gives us the Hilbert space kinematics of QM is Information Invariance & Continuity (wording from 2009 by Caslav Brukner and Anton Zeilinger). If you couch that physically, it means everyone measures the same value for Planck’s constant h, regardless of their spatial orientations or locations relative to the source. Let me call that the “Planck postulate” in analogy with the light postulate. Since h is a constant of Nature per Planck’s radiation law, just like c is a constant of Nature per Maxwell’s equations, and since inertial reference frames are related by spatial rotations and translations as well as boosts, the relativity principle says the Planck postulate must be true just like it says the light postulate must be true.

This means quantum information theorists have rendered QM a principle explanation, just like special relativity, exactly per Rovelli’s challenge. Accordingly, quantum superposition and entanglement are not dynamical effects resulting from some nonlocal or superdeterministic or retro causal mechanism. They are kinematic facts that result from the observer-independence of h as required by the relativity principle and Planck's radiation law (NPRF + h). This is in total analogy with the fact that length contraction and time dilation are not dynamical effects resulting from some causal mechanism like the luminiferous aether. They are kinematic facts that result from the observer-independence of c as required by the relativity principle and Maxwell's equations (NPRF + c).

Accordingly, NPRF + c can be understood as an “adynamical global constraint” on the configuration of worldtubes for bodily objects in spacetime and NPRF + h can be understood as an adynamical global constraint on the distribution of quanta among those worldtubes. This “all-at-once explanation” has been used by Evans, Liu, Price, and Wharton for retrocausality, Esfeld and Gisin for Bell flash ontology, Hance, Hossenfelder and Palmer for superdeterminism, and Adlam and Rovelli for relational quantum mechanics. [The term "all at once explanation" was introduced in “Reconciling spacetime and the quantum: Relational Blockworld and the quantum liar paradox,” W.M. Stuckey, M. Silberstein and M. Cifone, Foundations of Physics 38(4), 348 -- 383 (2008).]

This principle account of QM deflates the measurement problem and avoids the belief that, as stated in Allori’s article, “In the quantum world, interactions across vast distances can occur, non-local interactions.” It also supports an ontology that is “back down to three-dimensional Earth.”

For details, see our book, "Einstein's Entanglement: Bell Inequalities, Relativity, and the Qubit" (Oxford UP, 2024) or our open access paper cited above).