Sure. And facts are extremely hard things to find. With all the money we spend on science, we have a relatively small number of them. What individuals have is mainly opinions about facts.
That's why discussions seeking truth are such hard and subtle work. It's also why facts are frequently irrelevant to people's behaviors in this realm. See, for example, this graph:
http://www.gallup.com/poll/149390/record-high-approve-black-...
It isn't a graph of people coming to reasoned understanding on a topic. It's a graph of people with old opinions dying off.
> It is possible for a PhD to learn something from an undergrad. Moreover, it isn't strictly less understanding anyway, it's a different perspective. Which is all the more reason why people should try to hear each other.
I strongly believe it is less understanding. As a member of various dominant groups, my understanding of things like race and gender was very coarse. That's because I didn't have to pay any attention to those things; they almost always worked in my favor. When that's not the case, people are forced to pay more attention.
If you want to argue that generally attention does not lead to better understanding, you're really arguing that discussion is futile, because a major function of discussion is to turn people's attention to a topic.
> Not listening to someone (i.e. ignoring them) is not the same thing as attacking them because they said something you don't want to hear.
I agree with that, but don't see its relevance to the discussion. Could you say more?