Why is Second Life not a game?

Oy, I'm so tired of hearing the endless debate over whether or not Second Life is a game. Certainly it's a virtual world. Yes, there are games to play within it. And one could play loose with the definition of what a game is, loose enough that nearly any endeavor could be contained within the name.

However, I think it's worth saying that perhaps the most crucial elements of any game are the rules of conduct, and most important, the conditions for winning. SL does not have these conditions. There is no explicitly stated, agreed-upon end state. You can't win a game if you don't know how to win. Without this in place, there is no game.

And yet, what about MMOs in general? There is no end state for most of them; you're meant to play forever. There is no win condition. So, are MMOs games? What about the rules of conduct? There are rules to prevent griefing, but those affect only your continued ability to play, they don't cause you to lose the game itself, unless being banned is considered defeat.

So if neither SL nor any other MMO is a game, what are they? Sure this is silly, but think about it for a bit. What's your definition for an activity to be considered a game? Is it broad enough? Is it refined enough? Does it differentiate between Second Life and World of Warcraft?