The discussion is not always polite. It is interesting and enlightening, however. And it disciplines participating thinkers in a way that few other mediums manage.
I have just started reading David Weinberger's new book, Too Big to Know. He argues that the Internet is changing our notion of knowledge. In particular, it reduces the power of authorities to designate what gets written down as truth. Instead, all ideas remain in play. In arguments, Weinberger suggests that there is a Newtonian property of facts: "For each fact, there is an equal and opposite fact."
I think that what we observe in political economy is that people tend to align facts to fit their beliefs, rather than the other way around. The stronger a person's beliefs, the more limited will be the range of facts and theories that the person will consider.
I am not saying that we have to treat all beliefs as equally true. But when I disagree with someone, I think it is best to assume a non-zero probability that I am wrong and to use an appropriately moderate tone in order to be consistent with such an assumption.