Is Intersubjectivity Proven? A Reply to Khrennikov and to QBists

In two recent papers Khrennikov uses what he calls Ozawa’s intersubjectivity theorem to claim that intersubjectivity is necessarily verified in quantum mechanics and to criticize QBism and more generally all interpretations that are perspectival. In agreement with two previous QBist’s papers, I explain here why Khrennikov’s proof is not valid but in contrast with one of these papers, I criticize the way intersubjectivity is dealt with in QBism.