>[!abstract] >In economics, Knightian uncertainty (named after economist Frank Knight) is a lack of any quantifiable knowledge about some possible occurrence, as opposed to the presence of quantifiable risk. It exists when probabilities cannot be assigned to outcomes. This differs from risk, where probabilities are known or can be estimated. >[!related] >- **North** (upstream): — >- **West** (similar): — >- **East** (different): — >- **South** (downstream): —