 There has been considerable research in the framework of so-called ‘generalized probability theories’ or ‘Boxworld’ on the problem of what information-theoretic constraints in the class of ‘no signaling’ theories would characterize quantum theories. See Brassard 2005, van Dam 2005, Skrzypczyk, Brunner, and Popescu 2009, Pawlowski et al. 2009, Allcock et al. 2009, Navascues and Wunderlich 2009), Al–Safi and Short 2013, and Ramanathan et al. for interesting results along these lines. Chiribella and Spekkens 2016 is a collection of articles based on a conference at the Perimeter institute of Theoretical Physics in Waterloo, Canada on new research at the interface of quantum foundations and quantum information. See Fuchs 2014 for a discussion of QBism, a radically subjective information-theoretic perspective. 