This question is related to References for particular definitions of risk and uncertainty, which offers an excellent description of risk and uncertainty.

Just as a recap: Knight (1921) described risk and uncertainty as two different beasts.

"Uncertainty must be taken in a sense radically distinct from the familiar notion of Risk, from which it has never been properly separated.... The essential fact is that 'risk' means in some cases a quantity susceptible of measurement, while at other times it is something distinctly not of this character; and there are far-reaching and crucial differences in the bearings of the phenomena depending on which of the two is really present and operating.... It will appear that a measurable uncertainty, or 'risk' proper, as we shall use the term, is so far different from an unmeasurable one that it is not in effect an uncertainty at all."

Keynes (1921) similarily discussed the term probability.

Now I am looking for a term that encompasses all three types (risk, uncertainty, probability) of "uncertainty" without being tautological. Is there something better and more concrete than saying "situations that involve risk or uncertainty"?

  • $\begingroup$ How can something be both a measurable probability as well as fundamentally uncertain - which implies that we cannot put a probability distribution on it? $\endgroup$ Jun 22, 2020 at 14:14
  • $\begingroup$ @BrianRomanchuk I do not exactly get your point. Can you elaborate? $\endgroup$
    – Karl A
    Jun 22, 2020 at 15:40
  • 2
    $\begingroup$ Acts with unknown consequences? $\endgroup$ Jun 22, 2020 at 19:06
  • $\begingroup$ @KarlA Lumping together “uncertainty” (as per Keynes) and “randomness” is joining two concepts that are viewed to be opposites. In what sense is that useful? Realistically, I don’t think anything other than “uncertainty” works. Maybe you can put a probability distribution on outcomes, or maybe you can’t - who knows? It’s uncertain. $\endgroup$ Jun 22, 2020 at 19:34
  • $\begingroup$ @BrianRomanchuk The fundamental idea of subjective Bayesians is that all these concepts can be subsumed under probabilistic reasoning. $\endgroup$ Jun 22, 2020 at 21:44


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