or,
14 [various people have pointed out reasons I ought to have included, so now it's 18 19 20 and counting] Reasons to be polite and decent to other people in online fandom, none of which have anything whatsoever to do with BNFs, Niceness, or Censorship. 1) They have previously been kind to you.
2) They have never been anything but kind, or at least pleasant, to you.
3) They are in a position to be kind to you in the future.
4) They are in a position to make you very, very sorry you ever opened your mouth. Or they will be in the future. Nobody's power base -- or lack therof -- is forever.
5) Among your audience there is probably at least one person whose good opinion you value, or who is in a position to do you either good or harm, who knows and likes the person you are about to be vile to.
6) They are very new, and therefore don't know all the rules and nuances yet.
7) They have been around forever, and probably understand things you don't about the rules and nuances.
8) They are clearly considerably less intelligent than you are, and you have too much pride to shoot fish in a barrel.
9) They are clearly considerably more intelligent than you are, and you have too much sense to invite a slapdown you'll still remember in painful detail when you are 90.
10) Appearances online can be deceiving. The fact of someone being very new to fandom, or just very young, or alternately much older and not terribly tech-aware, does not actually guarantee that they are not, for example, one of the world's leading authorities in the field you are discussing. This can lead to, once they have mastered the, for example, lj learning curve, and can express themselves clearly, a really really unpleasant burning sensation as your entire body turns flaming red with shame.
11) You'll do something equally stupid or in fact stupider sometime, and when that day comes your chances of getting out of there with your dignity intact will be much higher if half of fandom isn't quietly gunning for you.
12) You
have done something that stupid, and only by the grace of God and the forebearance of the people around at the time did you avoid public tar-and-feathers. It is, however, not safe to assume that they've all forgotten, or that they won't bring it up if you give them a good reason to.
13) Something tragic or traumatic will probably happen to you one day, and that will be a bad time to discover that you've established a reputation as a person who doesn't deserve or appreciate sympathy, kindness or tact.
14) One of the many ways in which fandom is not like high school is that fandom is full of extremely smart people. We are not short of clever around here. The bar for "So smart you will automatically be loved and admired, even if you behave like a wild squirrel brought indoors" is set much, much higher than you think it is, and you are probably in no danger of concussing yourself on it.
15) The nastier you are, the better your chances of carelessly hitting someone in an
extremely sensitive spot. Aside from being vile, this is extremely dangerous; you have a soft, tender underbelly too, and you don't want to hand anyone a reason to go hunting for it.
16) If your motive for nastiness is that you are terribly, terribly annoyed by stupidity, you may want to keep in mind that intelligent and meaningful conversations rarely break out in the middle of vicious slapfights.
17) Fandom functions almost entirely on reputation, and it has the collective memory of an elephant. The evil you do today will still be following you around in twenty years.
18) Showing off in public is, admittedly, The Fannish Way, but if your talent for nastiness is your most impressive and frequently displayed characteristic you're probably not actually going to enjoy the company of the friends and admirers that gets you.
19) There is a very good chance that you are later going to encounter them in person, or in a different context online, and realise that this is a person you'd very much have liked to know, if you hadn't stupidly poisoned the well at the start.
20) Emotional hangovers are no fun. What seemed like such a
clever little rant at 2 am looks very different when you wake up the next day with your adrenalin exhausted, realise that you were actually rather more general in your scope and venemous in your self-expression than the situation really warranted, stagger over to your computer, and see that you have 40 new comments, each and every one of which you suddenly dread reading.