Pitowsky’s Epistemic Interpretation of Quantum Mechanics and the PBR Theorem

In his work on the foundations of Quantum Mechanics, Itamar Pitowsky set forth an epistemic interpretation of quantum state functions. Shortly after his untimely death, Pusey, Barrett and Rudolph published a theorem—now known as the PBR theorem—that purports to rule out epistemic interpretations of quantum states and render their realist interpretations mandatory. If one accepts this conclusion, the theorem is fatal to Pitowsky’s interpretation. The aim of this paper is to cast doubt on this verdict and show that Pitowsky’s position is actually unaffected by the PBR theorem. Had it been a form of instrumentalism, the defense of Pitowsky’s view would have been trivial, for according to its authors, the PBR theorem does not apply to instrumentalist readings of quantum mechanics. I argue, however, that Pitowsky’s position differs significantly from instrumentalism, and yet, remains viable in the face of the PBR theorem.