Probabilities of one-time events are unobservable and unmeasurable. According to empiricist and positivist principles, they must be meaningless. However, our cognitive limitations do not prevent entities and effects from existing. We show that the argument for existence of subjective...

Keynes's initial, introductory presentation of his inexact measurement, approximation approach to interval valued probability occurred on pages 38-40 of chapter III of the A Treatise on Probability. Keynes used a simple diagram on page 38 to illustrate the non linear and non additive nature of...