  I contrast two possible attitudes towards a given branch of physics: as
inferential (i.e., as concerned with an agent's ability to make predictions
given finite information), and as dynamical (i.e., as concerned with the
dynamical equations governing particular degrees of freedom). I contrast these
attitudes in classical statistical mechanics, in quantum mechanics, and in
quantum statistical mechanics; in this last case, I argue that the
quantum-mechanical and statistical-mechanical aspects of the question become
inseparable. Along the way various foundational issues in statistical and
quantum physics are (hopefully!) illuminated.
