setup ever has a determinate answer. In Fuchs’ own wording the main motivation for this astonishing claim is the following:

> Take, as an example, a device that supposedly performs a standard von Neumann measurement $\{\Pi_d\}$, the measurement of which is accompanied by the standard collapse postulate. Then when a click $d$ is found, the posterior quantum state will be $\rho_d=\Pi_d$ regardless of the initial state $\rho$. If this state-change rule is an objective feature of the device or its interaction with the system—i.e., it has nothing to do with the observer’s subjective judgement—then the final state must be an objective feature of the quantum system. ([@Fuchs] p.39)

According to this line of thought, if we suppose that the question of which observable some value obtained in an experiment is a value of has a determinate answer, applying the projection postulate to the state assigned to the system prior to measurement results in a uniquely determined post-measurement state, depending only on the observable measured and the measured result, not on the state assigned previously. But this means that assigning any other state than the one obtained from application of the projection postulate would be wrong. At least with respect to 