I've been studying a lot of Deleuze in the last few weeks. Because of this, I have a giant bundle of tangled thoughts working their way toward design-oriented theories, but they are difficult to elucidate and may take me some time. Today one such idea crystallized, and here it is...
Deleuze made a distinction between the Virtual and the Possible. He said the former was something Real that could become Actualized, while the latter was something Not Real that could be Realized (that is to say, "Real-ized," or "made real").
The distinction can be tricky. I'll try to explain. I'm going to use the words "system" (a word we are all familiar with) and "assemblage" (Deleuze's term) interchangeably here.
The Possible, said Deleuze, is NOT Real, because it hasn't happened AND is not guaranteed to happen, given nothing but the existence of the system itself. However, contingent upon certain events occurring between objects within the system, it might be Real-ized. The Possible, therefore, is a multiplicity of system states, each of which depends upon some event or action in order to become Realized. At the moment that happens - IF it happens - it becomes no longer Possible, but Real.
The Virtual, on the other hand, is always Real, whether or not it is currently manifest in an Actualization. That's because the Virtual is a "field" of effects that emerge via contingencies within the entire assemblage (or system). When the system as a whole enters a certain state, this or that particular Virtuality may become Actualized. It might be said that at that point, the objects within the system are guided by the imperatives of the Virtual, rather than "causing" anything to happen. In addition this new Actuality may affect the Virtual Field, giving rise to new Virtualities.
THE POSSIBLE: If you throw a basketball toward the basket, hoping to sink it, you may or may not succeed. The event of sinking the ball is Possible. But before it actually happens - i.e. before sinking it becomes Real-ized - it is Not Real. And if you miss the shot, it never becomes Real.
THE VIRTUAL: If you release a bunch of hydrogen molecules and oxygen molecules into a space with no intensive properties (i.e., no extremes of temperature, weird gravitational fields, or whatever else might cause a different effect), the fact that many of them will form into water molecules is Virtual; that is to say, it is an emergent property of the assemblage (the whole assemblage in this case being hydrogen molecules, oxygen molecules, and the space they meet in). The fact that hydrogen and oxygen bond to form water is Virtual; that is, it was already present in the Virtual Field of the system, even before the first two molecules bonded. We might even say that the Virtual Fact of bonding drives the actions of the individual molecules, for it does not seem that the molecules engaged in any decisions or actions "on their own."
The Virtual is Always Real even when not manifest, but emerges into Actualization in certain system states.
The Possible is Not Real until some action occurs within the system that causes it to become Real-ized.
Let's see if we can put this in game system terms:
THE POSSIBLE: We're playing D&D. Your character has been stung by a giant wasp. You need to make a saving throw. At this moment your character's death is Possible (let's call that State 1), and your character's resistance to the poison is also Possible (State 2). You roll the dice and look at the result. The moment you do that, one of these two states becomes Real-ized. The other simply ceases to be Possible, it was never Real anyway.
THE VIRTUAL: We're playing Fiasco. At a certain point (the mid-point) of the game, we all know that The Tilt is going to happen. We don't know what it will be, of course, but we know that the story will take a drastic and destabilizing turn at that point. As long as we don't stop the game early we can say that the fact of The Tilt (ie, the fact that The Tilt will happen) is Virtual, but depending on what we roll, the precise details of that Tilt - each 1 out of 36 distinct potential results - are only Possible.
It seems to me that almost all of the game mechanics we use almost all of the time involve Realizing the Possible, rather than Actualizing the Virtual.
It also seems to me that this sort of thinking - about Actualizing the Virtual - may be (?) more applicable to genre sims and narrativist forms than simulationist or gamist forms. (Let me know if you concur, I'm still thinking that through.)
In any case, it might behoove us to begin thinking more about Actualizing the Virtual, and finding ways to incorporate these sorts of dynamics into play. We might just turn up a whole new category of design possibilities and playstyles.