[Epistemic status: I'm mostly trying to outline a class of strategy that you could use to do something rather similar to what people term "flirting", rather than say that everything that's ever called "flirting" fits this model. I'm lowering my standards so that this gets posted at all instead of sitting in my drafts folder, so I might've made some important mistakes somewhere.]

In this post, I'll use "X is common knowledge between you and me" to not only mean "you know X and I know X," but also "I know that you know X" and "I know that you know that I know X" and so on (this is pretty standard in mathematical logic contexts, although distinct from the colloquial meaning). The simplest way to get common knowledge of X is for one of us to just say X out loud.

These ideas are only partially my own: I've read bits and pieces of this theory in different places in the past few years. I haven't been able to find sources for most of it. I know some of it is scattered across Planecrash, and reading that story is what got me thinking about this again recently, but that's probably not their original source. As far as I can tell, I'm the only person to synthesize them all together in a post, but please let me know if I'm wrong.

What is flirting?

As stated above, this is less about trying to describe everything ever called flirting, rather trying to outline a strategy that can exist and then exploring the implications of that strategy.

Consider the situation where person A is romantically attracted to person B, but they're currently just friends. Flirting-like strategies likely apply more generally, but the romantic case is a good starting point. Let's say that person A's values are approximately:

• If B can counterfactually reciprocate the romantic attraction, then A wants them to be in a romantic relationship where that attraction is reciprocated.
• Otherwise, A wants to maintain the friendship with as little turbulence as possible.

(If you want to pause and ponder, pause right here, since I outline the strategy in the next paragraph.)

In certain social contexts, it's totally fine to just make the attraction common knowledge and move straight to the "A and B are in a romantic relationship" or the "nothing changes" outcomes. But in other cases, it can make a lot of sense for people to take things slower and convey the information in a more subtle way. Flirting is the deferment of common knowledge of attraction, and instead opting for sending little bits of Bayesian evidence about attraction. Instead of reaching common knowledge instantly, it takes some time get there, or never gets there at all. This has benefits over the "person A just makes it common knowledge immediately" approach:

• It lessens the expected stress on person B, since they no longer have to make a decision on a short time scale about whether or not they reciprocate the attraction, if they don't already know. Being non-stressed is good for consent!
• This deferment is fun for a lot of people, since it's a social game involving a romantic interest.
• If, in response to person A flirting, person B starts "anti-flirting" (doing the same thing but instead giving evidence of lack of attraction), then the "we're still just friends" world hasn't been explicitly ruled out from the perspective of common knowledge, and this allows people to more smoothly return to that world if things don't work out.
• Deferment distributes the emotional vulnerability for person A across time, rather than one big vulnerable moment where common knowledge is established with person B.

Generalization?

It really seems like this can be generalized beyond romantic contexts, but right now I am just trying to get these ideas out on the internet, rather than explore every possible corner of them. Some related-feeling things that might be interesting to explore this class of strategies with:

• Asking someone to put their resources towards a project of yours, but you want to apply minimal pressure on them and you are okay with things taking a bit longer.
• Working in an adversarial environment where you can't communicate freely but still need to find allies

There are definitely more avenues to theorize about this. I especially feel like I didn't capture how flirting interacts with the finer tensions in the social fabric, and I'm interested to hear other people's ways of articulating this.