The Open Thread posted at the beginning of the month has gotten really, really big, so I've gone ahead and made another one. Post your new discussions here!
This thread is for the discussion of Less Wrong topics that have not appeared in recent posts. If a discussion gets unwieldy, celebrate by turning it into a top-level post.
For the most part, observing what pronouns we use for each other should provide this information. If you need to use a pronoun for someone that you haven't observed others using a pronoun for, it's safest to use they/xe/e and, if you think that it'll be useful to know their preference in the future, ask them. (Tip: Asking in that kind of situation is also a good way to signal interest in the person as an individual, which is a first step toward building alliances.) Some people prefer to use 'he' for individuals whose gender they're not certain of; that's a riskier strategy, because if the person you're talking to is female, there's a significant chance she'll be offended, and if you don't respond to that with the proper kinds of social signaling, it's likely to derail the conversation. (Using 'she' for unknown individuals is a bad idea; it evokes the same kinds of responses, but I suspect you'd be more likely to get an offended response from any given male, and, regardless of that, there are significantly more males than females here. Don't use 'it'; that's generally used to imply non-sentience and is very likely to evoke an offended response.)
Of the several things I could say to try to explain this, it seems most relevant that, meaningless or not, gender tends to be a significant part of humans' personal identities. Using the wrong pronouns for someone generally registers as a (usually mild) attack on that - it will be taken to imply that you think that the person should be filling different social roles than they are, which can be offensive for a few different reasons depending on other aspects of the person's identity. The two ways for someone to take offense at that that come to mind are 1) if the person identifies strongly with their gender role - particularly if they do so in a traditional or normative way- and takes pride in that, they're likely to interpret the comment as a suggestion that they're carrying out their gender role poorly, and would do a better job of carrying out the other role (imagine if I were to imply that you'd be better at creating staples than you are at creating paper clips) or 2) if the person identifies with their gender in a nonstandard or nontraditional way, they've probably put considerable effort into personalizing that part of their identity, and may interpret the comment as a trivialization or devaluation of that work.
Oh, okay, that helps. I was thinking about using "they" for everyone, because it implies there is more than one copy of each poster, which they presumably want. (I certainly want more copies of myself!) But I guess it's not that simple.