This essay on why people are rude online is interesting, although I think it mostly overlooks one of the key dynamics of online speech: When you write online, you don’t know who is in your audience. In regular speech, you know who your audience is because you observe the audience directly. As a result, you can tailor your speech to the audience you see. If you are speaking to a bunch of your college friends you might say one thing; speaking to a large roomful of business executives, another; and speaking to a room of third graders, something else. Each audience has its own set of social norms, and we naturally tailor our style of speech to that audience we see based on our expectations of what is proper for that audience.
When you write online, in contrast, you don’t see who is reading what you are writing. The audience is unseen and usually largely unknown. This is just my amateurish speculation, but my guess is that a lot of people have a natural tendency to write by implicitly imagining the kind of audience that would be around them in the physical space where they are writing (even though their actual audience is online). Because those physical spaces can be pretty intimate places, such as a person’s home, a lot of people tend to make online communications that use the kind of language they would use when amongst friends. The speech is more unfiltered and more expecting of shared values. When the audience turns out not to share those values, though, they experience the unfiltered speech as rude — which leads them to respond with similar or even greater rudeness. That’s my amateurish speculation, at least.
Thanks to Paul Horwitz for the link.