> In QBism the quantum state of a system instead represents an agent's beliefs about what will happen in future interactions with the system. Okay, I think thi

> In QBism the quantum state of a system instead represents an agent's beliefs about what will happen in future interactions with the system. Okay, I think this is my problem. I don't see how these kinds of statement are about quantum mechanics specifically. For example, I could say "In Newtonian mechanics, the classical state of a system represents an agent's beliefs about what will happen in future interactions with the system.". To me, that sentence tracks exactly as well as the quantum variant. But surely qbism is more than just some kind of hardcore solipsism applied to superpositions. It also seems that the claim that a quantum state can't be portrayed with objective, observer-independent variables is simply wrong. We all agree on how to objectively represent the spin of an electron: as a vector in Hilbert space. And different observers doing an experiment will come to agree on which specific vector to use.