you'll learn that authorities on certain matters aren't as bright as you once believed them to be.
Hmm, but if you’re right, then you’re the authority and we learn that you’re not as bright as we were led to believe.
So, maybe they’re right, but then, we learn that they aren't as bright as we once believed them to be.
So perhaps you’re right, then you’re the authority and we learn that you’re not as bright as we were led to believe.
That would make them right, but then, we learn that they aren't as bright as we once believed them to be.
Circular circle ad infinitum
Btw, which “certain matters” are meant here?