probability Probability Matthew Diller William R. Hogan A data item that is about a proposition and has a numeric value between 0 and 1, inclusive, that is the output of some process of inference, such that 1) logical falsehoods and logical truths are assigned a value of 0 and 1, respectively, while contingent propositions are assigned some intermediate value; and 2) the process of inference conforms with rules for the calculation of probabilities, and that any interpretation of probability must specify the extent to which probabilities might be used to constrain the degrees of belief of rational agents. A data item that is about a proposition and has a numeric value between 0 and 1, inclusive, that is the output of some process of inference, such that 1) logical falsehoods and logical truths are assigned a value of 0 and 1, respectively, while contingent propositions are assigned some intermediate value; and 2) the process of inference conforms with rules for the calculation of probabilities, and that any interpretation of probability must specify the extent to which probabilities might be used to constrain the degrees of belief of rational agents. The first criterion is derived from Kolmogorov's Probability Calculus, while the second is derived from Salmon's Admissibility and Applicability Criteria of Adequacy. Salmon's ascertainability criterion is subsumed by the definition for 'data item'. data item