So I’m doing Nanowrimo (and I recommend everyone has a go at least once, even if you only end up with a thousand words by the end of it, you’ll have more than you started with) and have been trundling along at a reasonable clip, managing to keep up so far. But the other day I was writing a scene with the crew of a spaceship chatting about something, what to do next or some such, and I realised that not only was that boring, but it was too nice. So since my Captain, Laura Shields, tends a bit towards the irreverent and stupid on some things, I decided to do what all writers must do.
It was time to be mean.
Now I tend to agree with the consensus that, on the whole, the job of a writer is to be an asshole to their characters, to be the one who makes their life hell so they can come through it stronger, or weaker, but either way definitively changed. In some cases, dead, which I’m sure you’ll agree is a hell of a change. So I decided that it was time for the Captain to screw up on a tiny bit of interaction with the ship’s AI, and since the AI is a full fledged person this was enough to actually hurt her.
What has this to do with writing what you know, phantom people who may exist only in my fevered hallucinations are no doubt asking? Why that’s the very thing, I took the interaction from one of my very own fuck ups of this sort, and I think the scene is better for it. Like me, Laura didn’t realise what she had done because she was thinking about other things and generally being an inconsiderate dumbass. Also like me, she was immediately called on it by her crew and, I hope (there’s still a long way to go just on this first story with them) has learned from it. Now, I didn’t need to use my own experience for this, I could have just made something up that made sense and gone from there.
But it was a hell of a lot easier, and more convincing, to write from what I’d experienced.
Also, in an odd way, it gave me a kind of final ownership over my fuck up. Recognising I’d been shitty, owning up, then showing how it can happen have helped solidify the checks needed in my mind so that it won’t happen again. I hope. We’re all human, mostly.
So yeah, writing what you know, useful in a whole range of ways and for more than just the writing. But, I think the phrase ‘write what you know’ is a bit problematic, since it seems to imply only ever writing about what you’ve experienced.
And I’ve never insulted an artificial intelligence.
A better (in my opinion, which you can take, leave, or fling away in the desperate hope to never see it again but know this: like a boomerang it will come back to haunt you) way of saying it might be: ‘know what you write’ which, while still somewhat ambiguous, at least puts the impetus on ‘knowing’. And I can know all kinds of things without experiencing them, just from reading and watching and generally taking notice.
Basically I’d prefer it if everyone felt safe to write whatever the hell they liked, and if you don’t feel like what you’ve written about is convincing, just read read read until you think you understand it, check that by explaining it to someone else, and then fix your writing appropriately.
…
No, this wasn’t me justifying my wiki walks and tv tropes traversals, shut up.
Incarnate Memory 
Agreed! Not least because writing only what I know in terms of my own personal experience would make for some relatively boring and sometimes slightly incomprehensible fiction. And perhaps most of all because one of the other things about reading and writing is that one can read/write to explore: situations I’m unlikely or unable to ever experience get evaluated, considered, planned for, have emotions thrown at them until something sticks, and maybe I’ll learn a couple vaguely useful lessons along the way. Or maybe not. Regardless, I find it interesting and useful! Meanwhile, the things I do know inform the (many) things I don’t know, and outside of that hello other people, Wikipedia, TVT, and the wider Internet, you are my friend.