  In a recent no-go theorem [Bong et al, Nature Physics (2020)], we proved that
the predictions of unitary quantum mechanics for an extended Wigner's friend
scenario are incompatible with any theory satisfying three metaphysical
assumptions, the conjunction of which we call "Local Friendliness":
Absoluteness of Observed Events, Locality and No-Superdeterminism. In this
paper (based on an invited talk for the QBism jubilee at the 2019 Vaxjo
conference) I discuss the implications of this theorem for QBism, as seen from
the perspective of experimental metaphysics. I argue that the key distinction
between QBism and realist interpretations of quantum mechanics is best
understood in terms of their adherence to different theories of truth: the
pragmatist versus the correspondence theories. I argue that a productive
pathway to resolve the measurement problem within a pragmatist view involves
taking seriously the perspective of quantum betting agents, even those in what
I call a "Wigner bubble". The notion of reality afforded by QBism, I propose,
will correspond to the invariant elements of any theory that has pragmatic
value to all rational agents -- that is, the elements that are invariant upon
changes of agent perspectives. The classical notion of `event' is not among
those invariants, even when those events are observed by some agent. Neither
are quantum states. Nevertheless, I argue that far from solipsism, a
personalist view of quantum states is an expression of its precise opposite:
Copernicanism.
