I have long maintained that conservatives are much better at providing an objective rationale for their point of view than are liberals. I do think it is difficult for most liberals to make a case for their side without making uncomplimentary remarks or aspersions (though I know or know of a few who can.)
I think it is for this reason that liberal politics/advocates overall tend to be more negative and contentious than those on the right. They often give the impression of being against something more than they are for something.
Having said that, it doesn't take much effort to find predominently conservative websites/message boards on which there are some very adolescent, hateful, and stupid remarks. My partisan bias shows when I find these embarassing while I expect to find it on predominently liberal sites.
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I think hate speech from either side is unbecoming, unproductive, and makes the person using it appear to be unintelligent or, at the very least, uneducated/uninformed.
My personal policy is not to engage in debate by insult. That keeps me from blowing my cool. Okay, it USUALLY keeps me from blowing my cool.
I recommend the policy anyway.