there's no reason I would want to be polite with people who see no problem being rude to me.

Then expect to be downvoted - anyone else being rude to you will be downvoted as well (not necessarily on net).

By "groupthink" I mean that people are disagreeing with me simply because other people are disagreeing with me and because I already have negative karma. I also mean that they aren't considering my arguments fairly, they're only looking at the issue from a one sided perspectively. I'm pretty sure that this is a standard interpretation of what "groupthink" means.

Leaving aside the common "people are disagreeing with me" interpretation, I still don't think that's what people (non-technically) mean when they use the word "groupthink". "Groupthink" (in the popular usage) implies that there are beliefs common to the group that are not questioned - for example, accusing Less Wrong of "groupthink" because a comment against cryonics was highly criticized would be the common usage.

Really, it should not be used that way either though, since it's too similar to the technical meaning of the term but entirely wrong.

You're playing with semantics and taking quotes literally. ... You're willfully being confused here.

No, I was not confused about what you meant - I was pointing out how it was not obvious. If you say "Obviously X" and I think X is also obvious to me, then I still might have grounds for arguing that X is not obvious in general. In fact, unless you're talking about something like the color of an object that a particular group of people are currently staring at, it's best to assume that nothing is obvious. If you do use the word "obvious", you should expect objections from people who did not find it obvious, and expect some of them to feel that you are insulting their intelligence.

I do not see how I was playing with semantics. Yes, I take what you write literally. If you do not want me to read the words that you write, then do not write them on this website, as I will probably get around to reading all of them eventually.

Nothing that you said here is relevant to what I was contending.

Usually, "if my comment was wrong" refers to its factual accuracy, not the quality of your reasoning. So following an accusation of overconfidence with "that would only make sense if my comment was wrong" is misleading.

It is easier to reject a viewpoint if other people do not find that viewpoint credible....

I'm familiar with that effect, but I don't see how it's a response to either of my statements.

No, I started receiving lots of bad karma after a post I made in the earlier thread, and that trend spread to here.

Well I, for one, did not read or downvote anything you said in that other thread until I read this one. Now I've gone back and downvoted all the low-quality comments you made in that thread (note: that is not all of your comments).

there are people going around downvoting everything I write simply because I am the one who wrote it. That is stupid.

There are more constructive things to call that behavior other than "stupid". And I'd like to know how you know that's what people are doing - I have no tools that let me detect that, and looking back at your comment history you have some recent comments that are not at a net negative.