Risk vs Uncertanity
in economics and otherwise too
https://cals.arizona.edu/classes/rnr485/ch6.htm
But economists recognize that in a multifaceted economy with many investment instruments with varying degrees of risk, no single discount rate exists that will measure all possible time preferences and returns to capital. There are many possible discount rates. [Note: risk = probabilities of outcomes are known, vs. uncertainty = probabilities of outcomes are unknown]
