Now, there's a lot to be said for calm and friendly exchanges -- especially on abstract philosophical topics, but it's also an appropriate ideal for political issues of reasonable dispute, where each party can hope to learn from the other in a climate of mutual respect.
But not all topics are like that, and there is a legitimate place in public discourse for passionate polemic and harsh criticisms. Some false views are sufficiently misguided and pernicious as to warrant our scorn, and not merely our calm deductive refutations.* It is not necessarily appropriate to politely engage with homophobes or creationists as if their position merited serious consideration.** That could give them a false air of respectability, which they do not deserve. Some scientists avoid this problem by simply ignoring creationism, allowing the blight to fester unimpeded. Some partisans merely hurl insults, which doesn't achieve much either. One appropriate response to pernicious views, in my opinion, is reasoned polemic. You engage seriously with the view whilst making it clear that you don't take it seriously. You mock it mercilessly, but in the context of a substantive argument which establishes fairly and reasonably why it deserves to be so mocked. The aim: to prove the other view not just false, but ridiculous.***
* = Or, as Chris Clarke puts it, "it is not civil to discuss things quietly and collegially while people are dying because they can't afford medicine."
** = See my post on open-mindedness. We should of course be open to the possibility of revising our views. But absent any actual reasons to do so, we may be confident in rejecting those views for the time being.
*** = As Amanda Marcotte writes: "Mockery is an excellent way for people to convey their values systems and progressives shouldn’t cripple ourselves by abandoning this tool. Just as mocking someone’s race encourages racist values, mocking someone for being racist encourages anti-racist values."
Different people may disagree on what views deserve such polemical treatment. I expect many would include homophobia, racism, sexism, holocaust denial, torture-apologetics, creationism, religious fundamentalism, etc. Some might add climate change denial, strict egalitarianism, ethical relativism, absolutist deontology, or propertarianism.
This is a legitimate part of civil discourse. If people don't want to risk public criticism then they shouldn't advance pernicious ideologies. I'm not going to treat respectfully the views of a homophobe or a torture apologist, nor those who value property more highly than people. I will engage with them seriously and sincerely, and do my best to rationally show why their views are ridiculous. In so doing, you can expect me to express both my arguments and my ridicule.
Such polemic is still bound by important intellectual/ethical standards, to help prevent misguided polemical abuse of undeserving targets. In particular, it is crucial that harsh criticisms still be reasonable criticisms. So if my criticisms are shown to be unreasonable then I will retract them and apologize. Intellectual honesty demands no less. That's simply the risk one takes in playing the polemic game: if you go wrong, you've got to take responsibility for that. It does take some discernment, and won't always be appropriate. But strong criticism per se need not be denounced as "uncivil". So long as it's backed with adequate substantive argument, such reasonable criticism can be an entirely appropriate contribution to public discourse. Some views ought to be publicly recognized as ridiculous. But as with anything else, the way to establish this is through critical reasoning.
So, to clarify my views on "blogging ethics", let me reiterate my firm commitment to reasoned argument and intellectual honesty. And let me also emphasize that this is perfectly consistent with justified polemic that may occasionally offend the thin-skinned. I don't think it's necessarily wrong to cause offense. Sometimes the truth hurts. (As Steve Gimbel writes, "There is no right not to be offended. Reality is an offensive place. Deal with it.")
See also my old post on "attacks and arguments".
Update: scrap that. The above describes a legitimate blogging-ethical policy. But it isn't mine.