You said: "So it seems there's an asymmetry between argument and authority. If we know authority we are still interested in hearing the arguments; but if we know the arguments fully, we have very little left to learn from authority."

I like your conclusion, but I can't find anything in your argument to support it! By rearranging some words in your text I could construct an equally plausible (to a hypothetical neutral observer) argument that authority screens off evidence. You seem to believe that evidence screens off authority simply because you think evidence is what makes authority believe something. But isn't that assuming the very thing you want to demonstrate?

Your scenarios in the first paragraphs are neither arguments nor demonstrations. They are statements of what you believe. Fair enough. But then I was expecting that you'd provide some reason for me to reject the hypothesis-- a hypothesis that carried a lot of weight during the era of Scholasticism-- that there is no such thing as evidence without authority (in other words, it is authority that consecrates evidence *as* evidence).

I used to wonder how anyone could take the obviously wrong physics of Aristotle seriously, until I learned enough about history that it dawned on me that for the Scholastic thinkers of the middle ages, how physics really worked was far less important than maintaining social order. If maintaining social order is the problem that trumps all others in your life and in your society, then evidence must necessarily carry little weight compared to authority. You will give up a lot of science, of course, but you will give it up gladly.

Obviously, we aren't in that situation. But I worry when I see, for instance, rational arguments for the existence of God that assume the very thing they purport to prove. And your argument (hopefully I've misunderstood it) seems a lot like those.