
 Quantum Logic and Probability Theory (Stanford Encyclopedia of Philosophy) 
  Mackey presents a sequence of six axioms, framing a very conservative generalized probability theory, that underwrite the construction of a ‘logic’ of experimental propositions, or, in his terminology, ‘questions’, having the structure of a sigmaorthomodular poset. 
  Thus, a state is a consistent assignment of a probability weight to each test  consistent in that, where two distinct tests share a common outcome, the state assigns that outcome the same probability whether it is secured as a result of one test or the other. 
  In classical probability theory (and especially in classical statistics) one usually focuses, not on the set of all possible probability weights, but on some designated subset of these (e.g., those belonging to a given family of distributions). 
 plato.stanford.edu /entries/qtquantlog (8000 words) 
