Over at Playing D&D with Porn Stars, Zak is exploring some of the same issues I've experienced attempting to talk with Forge adherents about what, exactly, gaming is and is supposed to accomplish. I pointed out Glenn Blacow's excellent article about different kinds of gamers, which is itself an exploration of the different expectations that people bring to the gaming table.
So what's my point? Simple: the process of negotiating the kind of role-playing game you want to play takes place between players as a part of gameplay as a social activity. Whatever you conclude becomes the basis for your social contract to continue - but there's no requirement that this be codified in the rules of the game. I would go further and argue that to codify such requirements into the rules places limits on role-playing within gameplay. Whether or not you want those limits is collectively up for negotiation.