Six Measurement Problems of Quantum Mechanics

The notorious `measurement problem' has been roving around quantum mechanics for nearly a century since its inception, and has given rise to a variety of `interpretations' of quantum mechanics, which are meant to evade it. We argue that no less than six problems need to be distinguished, and that several of them classify as different types of problems. One of them is what traditionally is called `the measurement problem' (here: the Reality Problem of Measurement Outcomes). Another of them has nothing to do with measurements but is a profound metaphysical problem. We also analyse critically Maudlin's (1995) well-known statement of `three measurements problems', and the clash of the views of Brown (1986) and Stein (1997) on one of the six measurement problems, concerning so-called Insolubility Theorems. Finally, we summarise a solution to one measurement problem which has been largely ignored but tacitly if not explicitly acknowledged.