  Quantum mechanics is reformulated using Hartle's definition of the state of
an individual physical system and a variant of von Neumann's propositional
calculus. An elementary set of quantum postulates lead inductively to the
familiar formulas of quantum theory, including the canonical commutation
relation and Schr\"odinger's equation. The expected value of the frequency of
events for an ideal ensemble is equal to the expected value of a state operator
for an individual system, producing a binomial probability distribution for the
determination of indefinite experimental propositions.
