|The Big Model|
Like or not, you're role-playing with other people. That means schedules, coordination, maybe travel ... basically, dealing with each other in all the ways that humans do. It's not just logistics, but emotions too. Someone likes someone else, or doesn't like them, a lot. One person doesn't like to be teased; another loves it. Bob and Diane are a couple, and James is crushed out on Diane. I could go on.
The Social Contract is whatever you people do that permits you to role-play, in the context of all this human stuff. The sting, though, is that even play itself is embedded in that social interaction - you can't escape it. You can't put it aside and then play, as if role-playing were some abstract act divorced from it all. You can't say, "These are the rules, but that over there is social." Using the rules is itself a social agreement, as well as how you use them, and what for. And if you're dealing with some rules which are tricky to manage, then how James thinks those rules apply to Diane's character ... starts to matter. A lot.
The key is not to blind yourself to reality and claim to play without that terrible social stuff messing it up. The key is instead to play with a positive Social Contract and with a genuine desire to play this game, with these people, right now.
All interactions and relationships among the role-playing group, including emotional connections, logistic arrangements, and creative expectations. All role-playing is a subset of the Social Contract.
One crucial component is the phrase "Let's play this game," which may or may not be understood and employed in a given group, and which becomes the Lumpley Principle when play begins. Failing to do so is a primary source of Murk.
Arguably some features of the actual Social Contract cannot be captured in verbal form. Therefore a Social Contract is not a written document or explicit agreement of any kind. When such things were employed among a group, they are a component and hopefully a facilitator of the actual Social Contract, including the statement "Let's abide by these."
Example of written pre-play agreement: Establishing social contract from invite onwards
Leadership and Authority
Sex & Sorcery, Adept Press