Definition
Plain language
Not knowing something that could be looked up or measured.
As stated in the literature
Reducible uncertainty arising from missing information or model ignorance; shrinks with additional evidence, tools, or training data.
Why it matters: Spotting this kind of uncertainty tells a system when to search, ask, or use a tool instead of guessing, since the answer already exists somewhere.
For example, not knowing the population of a city is epistemic uncertainty, because a quick lookup resolves it completely.
Heard on the show
“The first is epistemic uncertainty.”Episode 251 — When a Fake Dashboard Makes an AI Agent Just as Confident