I think it's a weird challenge. Like what's the shortest height that you're very confident that most people (> 50%) would consider tall? This is a tough question. You might get silence and tentative answers if you asked it. You might get different answers in different circumstances. But it doesn't mean "tall" is a concept we can't reason about confidently.

"What is the least X that you're confident of f(X)?" is just a hard question for any uncertain or vaguely defined X. Doubly so for an uncertain and vaguely defined X. But I don't think it tells us that much about X.