As wave after wave of privacy news arrives, it's easy to believe that public postings on social media sites are the problem. But I believe we are facing an issue caused not by public sharing but by an encounter with a new kind of "public". First, a short story.
Alice doesn't mind her photo being visible to everyone on Facebook. She put it there originally because she was flirting with Bob, and the fact everyone else could see it wasn't an issue. She had spent a lot of time understanding Facebook's privacy settings in all their labyrinthine splendour and she was pretty sure that the only people who could see personal details about her on Facebook were friends, and the only people who could see the stuff on her Wall were the girlfriends she goes out with when Bob isn't free, plus Bob (well, for all but one or two things!).
Alice is also a keen Twitter user. She has a different picture there - a flower at the moment, it was a kitten last month - and she's happy to have a public profile. Her tweets are rarely very personal - just comments on the news, LOLs with the girls, food favourites and a wink to the gallery each time she went out with Bob. She's been getting into Foursquare lately, checking-in at cinemas, restaurants and bars in a casually competitive way with the girls and with Bob's mates. She's often quite high in the league tables and she's the mayor of the wine bar round the corner from her flat.
When she split up with Bob, she actually used all of those social media services more than usual because she hoped the girls - and maybe one or two of Bob's mates - would rally round to make it hurt a bit less. That was OK for the first week, and she was distracted by fighting for top place in the Foursquare league table with Lavinia. Then one evening she was sitting in the sparsely-populated wine bar on her own, feeling depressed and Bob-less. Nursing a glass of the amazing Chardonnay that's not on the menu but which she's fallen in love with, she's lost in a miserable dream world when some guy she has never seen there before walks in and sit beside her.
He made a bee-line for her, as if she had a spotlight bean shining on her, asked if the stool next to her was taken and introduced himself as Evan. That wasn't something that had ever happened to Alice before - the guys always hit on her friends, never on her. Evan isn't really her type ; he's probably a few years younger than her and has the air of an extra from The Big Bang Theory. Alice is quite surprised when he asks the waiter for a glass of the same Chardonnay - by name. She'd assumed it was just the regulars who knew about it, and there was no way this Evan was a regular at the wine bar. She's even more surprised when Evan strikes up a conversation with her.
As they start to exchange trivia, Alice discovers Evan has seen almost every movie she's been to in the last two months. What's more, he liked all the same ones as her and hated all the ones she hated. She's starting to wonder if she's been missing out by her antipathy for geeks. When the last olive is eaten and Evan suggests they go grab a meal, her guard is down. So when Evan proposes dinner at the Greek place Bob used to take her to, she had no defenses left.
Public and Super-Public
I'm no novelist (all those names are borrowed from security theory) and I don't know how this story ends. But I do know Evan's secret. He was exploiting a new kind of "public" using an iPhone app called "Girls Around Me", which aggregated together information from all the social media tools Alice was using and gave him the ability to eavesdrop on her activities. Alice had a reasonable expectation that all her public activities would be seen by all her friends, and no particular concerns that any of them might be seen by strangers. She was engaging in what researcher Danica Radovanovic has called "phatic posts", providing public context to her life with what seemed trivial information in the same way as a group of friends in the real world might do.
In the real world, "public" is accompanied by practical realities that introduce a little friction. To listen to Alice and Bob in the wine bar, Evan would need to sit close enough to hear them, and they'd probably notice and change their discussion. To see all the places they went, he would need to take the time to follow them. His actions would quickly be apparent as obsessive and problematic - Rick Falkvinge explains this more.
But in the new "super-public" of data-mined social media, the friction is gone, and the sort of information Evan used to find and meet Alice was simply the product of triangulation between her posts. The software he downloaded for his iPhone did it all for him, although he is probably enough of a geek to stitch together scripts that would harvest the JSON from dozens of REST interfaces and use open source business intelligence tools to mine the resulting data. It's unlikely any privacy rules would even be implicated, let alone broken.
That's the issue here. Sharing information in phatic posts is normal and expected - it's just the translation of life in atom-space into life in bit-space. What's new is the super-public, the exposure of life to scrutiny by triangulation and data-mining. So far, no privacy legislation takes it into proper account. Companies, however are now actively mining the super-public.
Discussion of privacy treats it as a bilateral matter between the subject of the data and the application provider, focusing on "do not track" and application privacy settings. While this is important (as the scandal of Facebook's Social Reader shows). we need to move to a place - as Helen Nissenbaum has explained - where we see privacy as a matter of control of the flow of information across contexts. We need to discuss an legislate for the super-public.