Recently there has been a sharp increase in the amount of abusive language on the New Scientist website. No, it's not because our writers have become degenerates, it's because we rolled out a new commenting facility on all articles, giving people the chance to share their thoughts and opinions across the site.
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My pet theory about why people behave so rudely is that online commenting is treated, by most people, like a pub conversation – they don't necessarily expect to be taken seriously and the social rules are fairly relaxed. And yet, because comments appear in cold text without important cues like friendly body language, they can easily seem more offensive than if they would otherwise. As a result some people get annoyed, and the flaming and trolling begin.

guilty as charged
I know i've been immensely rude to other memestream users sometimes after coming in from the pub and having had a few drinks i've said things i would never say to a person's face or on sober reflection -- partly out of fear of being thumped whereas online i am physically safe

New Scientist Technology Blog: Don't flame me, bro'