It's true in a very real sense, though. Without calibration, how can you tell whether you're learning something real or something fictitious? Imagine trying to

It's true in a very real sense, though. Without calibration, how can you tell whether you're learning something real or something fictitious? Imagine trying to learn a language from a single teacher, without ever talking to or corresponding with a native speaker. How could you tell whether you're actually learning the language, or the teacher's unique dialect? Yes, you indeed "learned" something, it's just something that might not bear much resemblance to the real thing.