  The only acceptable reason why measurements are irreversible and outcomes
definite is the intrinsic definiteness and irreversibility of human sensory
experience. While QBists deserve credit for their spirited defense of this
position, Niels Bohr urged it nearly a century ago, albeit in such elliptic
ways that the core of his message has been lost or distorted beyond
recognition. Then as now, the objectivity of empirical science was called into
question. It was defended by Bohr along the lines of Kant's (then)
revolutionary theory of science, according to which the possibility of
empirical science hinges on the possibility of thinking of experiences as
experiences of a system of interacting, re-identifiable objects. What Bohr
added to Kant's theory was his insight that empirical knowledge was not
necessarily limited to what is directly accessible to the senses, and that,
therefore, it does not have to be solely a knowledge of objects of sensible
intuition. It can also be a knowledge of phenomena that are not objects of
sensible intuition but instead are constituted by experimental contexts, which
are objects of sensible intuition. Bohr's grounding of objectivity (or the
objectivity consistent with quantum mechanics), however, is weaker than Kant's
(or the objectivity consistent with Newtonian physics). This conclusion is
based on an examination of Bohr's intentions in appealing to irreversible
amplification effects or the sufficient size and weight of the measurement
apparatus.
