  A fundamental question in the debate about the interpretations of quantum
mechanics (QM) is whether the universe is fundamentally deterministic or
fundamentally probabilistic. This self-contained paper shows for a microsystem
made up of a single neutron that is initially at rest in a stationary
force-free environment, that even if the individual processes by which the
microsystem evolves are fundamentally deterministic as described by a strictly
deterministic model of the Elementary Process Theory (EPT), then still our most
precise knowledge of the outcome of a position measurement on the microsystem
is fundamentally probabilistic. Generalizing, the conclusion is that the EPT is
inconsistent with orthodox QM, but consistent with $\psi$-epistemic QM.
