This was in the context of a novice asking an expert, 'is this correct'. The point I was trying to make is that the novice may not be able to answer the questions with certainty but an expert can.
Have you ever met a student who walked out of an exam thinking s/he made an 'A' on an exam, only to find out that the actual grade was an 'F'? Sometimes everything can look correct and act correct (to the best of the knowledge of the novice), but is obviously incorrect when viewed at through the eyes of an expert.
And, at least from my point of view, for the novice it is much more helpful to know hat something is done correctly rather than spending many hours trying to make sure it is correct -- and still not being convinced. Self-study is infinitely harder when you do not have the answers to the problems to verify your understanding.