The weakness of QBism, in my opinion—and this is the turning point in this whole discussion—is that QBism anchors reality to a subject of knowledge, an “I” that knows, as if it stood outside nature. Instead of seeing the observer as a part of the world, QBism sees the world reflected in the observer. In so doing, it leaves behind naive materialism but ends up falling into an implicit form of idealism.51 The crucial point that QBism disregards, I believe, is that the observer himself can be observed. We have no reason to doubt that every real observer is himself described by quantum theory.
