In defense of the epistemic view of quantum states: a toy theory

Spekkens 2007: how much quantum 'look' a non-quantum theory can fake

what the source states

A toy theory built from classical states plus a restriction on knowledge finds that "a wide variety of quantum phenomena... have analogues within this toy theory" — interference-like behavior, no-cloning, teleportation, entanglement analogues — while explicitly failing to reproduce Bell-inequality violations and Kochen–Specker contextuality.

what we infer

The calibration standard this case applies to every "quantum-like" result in the observer-first literature: wave equations, complex numbers, branching, and interference-resemblance are all obtainable without quantum mechanics. The bar is the genuinely nonclassical correlation structure, and nothing below it counts.

limitations

• The toy theory targets ψ-epistemic interpretations, not idealism; its use here as a general calibration device is an editorial application.