Quantum Theory and ‘Reality’

Abstract

The main ambition of this work has been to explore the prospects for dissolving the foundational problems of quantum theory by adopting the epistemic conception of quantum states and reflecting on how it should be spelled out in detail. This differs (at least in emphasis, if not more profoundly) from the main ambition of those — ‘realistically minded’ — philosophers whose declared aim is to determine what reality is like if it is as quantum theory says. If the Rule Perspective is correct, quantum theory does not really say anything about reality at all: features of reality are described not by quantum states, but by NQMCs, and while quantum theory helps us ascribe probabilities to the NQMCs, it does not typically make any statements as to which NQMCs are true and which are false. However, even though quantum theory does not in that sense say anything about reality, we can learn a lot about reality by reflecting on what features it must have for quantum theory’s undisputed empirical success to be possible.