A core tenet of Bayesianism is that probability is in the mind. But it seems to me that even hardcore Bayesians can waffle a bit when it comes to the possibility that quantum probabilities are irreducible physical probabilities.
I don’t know enough about quantum physics to lay things out in any detailed disagreement, but it seems to me that if one finds a system that one cannot consistently make predictions for, it means we lack the knowledge to predict the systems, not that the system involves physical, outside-the-mind probabilities. For example, I could never predict the exact pattern of raindrops the next time it rains, but no one argues that that means those probabilities are therefore physical.
What is the Bayesian argument, if one exists, for why quantum dynamics breaks the “probability is in the mind” philosophy?
The main point here is that it can no longer be just our uncertainty in our map, something else must be added, which was the point.
Another way to say it is that probability can't just be in the mind, so while the probabilities encode our ignorance, it can't be all of the story (according to Wigner functions).
It was way down in the last comment, so maybe you should go to the end of the comment I linked here for more information.
Also, a difference here that doesn't matter for this discussion, but might matter for the general approach, might ultimately be that I disagree with this statement "since functions are a part of the map", because I think the map-territory distinction can often be blurry or fully dissolved in some cases, and also functions can have results when you evaluate them using an algorithm, making them part of the territory (for that specific function).