I often disagree with people who know more about a given topic than I do. For example, the typical economist who works in Industrial Organization is familiar with a lot more current antitrust research than I am. Robin Hanson notwithstanding, though, I'm not willing to defer to the IO expert's greater knowledge. After all, I reason, if I did immerse myself in the modern literature, it's a lot more likely that I would arrive at a sophisticated version of my current view than that I would radically change my mind.
When I argue with people who are better-informed than I am, then, I generally say the following: "I grant that you've seen a lot of evidence that I haven't. But here's my question for you: If I saw and read everything that you've seen and read, what would I conclude?"
Of course, the other guy could respond, "You'd agree with me," but he rarely does. When you frame the question as I have, it's often pretty clear that even though the disputants are not on a level playing field, that isn't the real reason why they hold different views.
One nice feature of my heuristic: It actually makes disagreement more informative. Suppose you have a well-informed friend who heavily disagrees with you. Nine times out of ten, he admits that if you knew what he knows, you'd still disagree. But one time out of ten, he insists that if you knew what he knows, you'd change your mind. As long as you trust your friend, such a statement makes it reasonable to immediately adjust your belief.
I suspect that Robin Hanson will be disturbed by my heuristic. After all, it lets every person retain his view that his prior is "special." You could even call my method the Anti-Hansonian Heuristic, because it deliberately ignores the fact that lots of smart people persistently disagree with you.
In response to Robin, though, I'd say that (a) it's almost impossible to convince anyone that his prior isn't special - and my heuristic improves the quality of beliefs despite this impasse; and (b) since my prior is special (laugh if you must!), this is a great heuristic for me to live by.
P.S. Another nice feature of my heuristic: You can occasionally run an audit. One time out of ten, you can actually put the better-informed person on the spot: "OK, share your evidence, and let's see if I react to it as you predicted."