This note argues that a representation of the epistemic state of the individual through a non-additive measure provides a novel account of Keynes’s view of probability theory proposed in his Treatise on Probability. The paper shows, first, that Keynes’s “non-numerical probabilities” can...

This paper advances an intuitive way to represent Keynes’s notion of long-term expectation. The epsilon-contamination approach is introduced and a rational and coherent decision rule is derived. The result is evidence that Ellsberg and Keynes share the notion of uncertainty and adopt the same...