I was just reading a paper <predatory publisher reference deleted> There is an argument (originally by Spekkens), in Section 2.1, that is supposed to be against psi-ontic interpretations. As I understand it, it's that if someone hands you a particle in state x+ or y+ you cannot tell the difference with certainty from a subsequent measurement. Although I realize this is true, the argument continues to say that, if those were 2 different ontic states then it's puzzling that you cannot necessarily tell the difference, and therefore taken as an argument against psi-ontic interpretations. This latter part is what I don't understand. Is there some reason to think that ontic states should be perfectly distinguishable from a single measurement? Why would this argument hold weight? I have similar issues with the other arguments against psi-ontic interpretations in this section. Any clarifications would be much appreciated.