HN tends to attract people from an educational/professional background that encourages critical thinking. Even if the user has a degree in the liberal arts, the application of their mind in technology forces their thoughts in a way that pushes them to think critically and not just accept what is given to them without question - I would think. As with all thoughts and theories, this is a general rule and a hypothesis, I might be way off the mark.
Generally speaking, though, people who have learned critical thinking skills seem more willing to discuss an issue in a reasonable manner and drill down to the truth of it, rather than "dig in" and just decide they're right with whatever information they might have on hand.
I only bring this up as I have a fine arts degree, but shifted into programming as I wrote scripts for different art applications and the transition was natural as I had a background as a script kiddie from my high school days. A large amount of the people I went to school with, however, are absolutely unwilling to apply critical thought to specific subjects even though some have masters degrees.