The ontological model framework provides a rigorous approach to address the
question of whether the quantum state is ontic or epistemic. When considering
only conventional projective measurements, auxiliary assumptions are always
needed to prove the reality of the quantum state in the framework. For example,
the Pusey-Barrett-Rudolph theorem is based on an additional preparation
independence assumption. In this paper, we give a new proof of psi-ontology in
terms of protective measurements in the ontological model framework. The proof
does not rely on auxiliary assumptions, and also applies to deterministic
theories such as the de Broglie-Bohm theory. In addition, we give a simpler
argument for psi-ontology beyond the framework, which is only based on
protective measurements and a weaker criterion of reality. The argument may be
also appealing for those people who favor an anti-realist view of quantum
mechanics.Comment: 13 pages, no figures. Studies in History and Philosophy of Modern
Physics, Available online 17 August 201
