Why not savoir? That's what the tip says.
→ Docteur, j'ai besoin de connaître votre avis.
→ Docteur, j'ai besoin de savoir ce que vous en pensez.
Can you explain the difference? I get that there's a difference between knowing a person (connaitre) and knowing how to swim (savoir), but your two sentences are talking about exactly the same knowledge in a way that requires different verbs.
I am wondering if the French are saying something more like "I need to hear your opinion" rather than "I need to have an understanding of it."
I think connaître is usually followed by a noun (or a modified noun), whereas savoir is usually followed by a clause (subject and verb).
Not always, sometimes it's a difference of strength. The example from my French teacher:
Je connais cette chanson -- I know this song (I am familiar with it)
Je sais cette chanson -- I know this song (I could sing it on stage)
I used connaitre but made another error, and it told me to use savoir. I used savoir this time and it told me to use connaitre.
I thought a French person would address him as Monsieur le docteur.
Why are you assuming the doctor is a man?
Docteur would be his title in this case.
Savoir is OK, surely? Perhaps the doctor is being obtuse? Come on, Doc, I need TO KNOW your opinion!
Why not "...je dois connaitre votre avis"? (I used the accent.)