Interactivity, Plot, Free Will, Determinism, Quantum Mechanics, and Temporal Irreversibility

Yes, believe it or not, these six things are all tied together. Moreover, they’re tied together in a way that reveals some useful truths about designing interactive stories. In this essay, I’ll trace those connections.

The starting point of the discussion is the conflict between plot and interaction. There are theoretical reasons for this conflict. They are best seen from the point of view of the plot faction. Many of these people are writers. Plot creation is, from their point of view, an enormously difficult task demanding great talent and creative energy. The thought of allowing an audience to mess up their carefully crafted plots leaves them cold. Knowing how difficult it is to get a plot to work well, they realize that any intrusion by the audience into the process will only yield garbage. If interactivity requires the audience to involve itself in the direction of the plot, then clearly interactivity and plot are incompatible.

Adding to this apparent incompatibility is the attitude of the other side. The protagonists of interaction tend to take a dim view of plot. The strongest example of this is the possibly apocryphal story about id software and the creation of Doom. There was, so the story goes, some dispute within the organization about the proper role of story in the game. One faction argued that there should be some story element to tie everything together. The other faction argued that Doom was to be an action game, pure and simple, and that "we don’t need no steenking story". Eventually, the anti-story faction won out, the losers left the company, and nowadays story is referred to within id as "the S-word". So the story goes.

Consider one of the most powerful storytelling products to appear on a CD: The Madness of Roland. (see "Review: The Madness of Roland”) (
expansion on this idea: How to Play God)This was a story with no interaction whatsoever. It would seem that the author of The Madness of Roland had said to himself, "we don’t need no steenking interaction".

What’s particularly interesting is that plot and interaction seem to contradict each other in the sales figures. The top games of the last year have been games with all interaction and no plot (Doom II) or games with all plot and no interaction (Myst, 7th Guest). Could it be that there is no workable middle ground?

So what we have here is an apparent incompatibility between plot and interaction. It would seem, from both theoretical considerations and direct experience, that plot and interaction cannot be reconciled. This in turn implies that the dream of interactive storytelling is a chimera.

The central issue that we face here is not new. In slightly different terms, some of the brightest minds in human history have struggled with this problem. The results of their efforts might prove illuminating. Now, you might wonder how a problem in game design could have attracted the attentions of august thinkers in times past, but in fact they weren’t concerned with games. They were working with bigger problems. OK, I’ll stop being so coy: I’m talking about the classic theological problem of free will versus determinism.

How did we get from games to theology? What’s the connection between "plot versus interactivity" and "free will versus determinism"? It goes like this: God is omniscient and omnipotent. Everything that happens in the universe happens according to His benevolent design. There are apparent evils in the universe, but these are all part of God’s greater intentions. But this must include the actions of people as well as the actions of natural phenomena. Thus, a terrible disaster is an "act of God", but so is a murder. How then can human beings have any free will? They are pawns in the hands of an omnipotent God. If we did have free will, then God would be neither omnipotent nor omniscient, for then He would neither control nor know what we would do. But if He is neither omnipotent nor omniscient, how can he fit any definition of god? Thus, free will clashes with determinism.

The connection with games should be obvious. Determinism in theology is analogous to plot in storytelling. Free will corresponds to interaction, for how else can a player interact without the exercise of his free will? Indeed, we can make the analogy more explicit by viewing the creative person as the Creator of a miniature universe. The storyteller, for example, creates an imaginary universe populated by his characters. Like some omnipotent god he decides their actions and predestines their fates. To reverse the analogy, the history of the universe is nothing more than a huge story written by God that we act out.

But wait! The games creator is also a god of sorts. He too creates a tiny universe and exercises godlike control over that universe. Yet, free will seems to exist in the game universe. What is the difference?

At this point, some people step forward with the observation that free will in the real world could be an illusion. After all, God would want us to think that we have free will, but in fact has already determined our actions for us. We think that we are making our own choices, but in fact our choices were predestined. Even if we try to assert our free will by deliberately making apparently arbitrary decisions, that too could be explained as God’s plan for us.

Now, the debate over free will versus determinism took a new turn about 70 years ago with the Heisenberg Uncertainty Principle and the introduction of quantum mechanics. The Uncertainty Principle established that the basic behavior of the universe was fundamentally random. That is, the most basic processes that underlie the functioning of the universe are unpredictable. This blows determinism right out of the water. If you can’t even be sure where an electron is or where it’s going, then you certainly can’t be sure what a complex system like a human being will do. Predestination just went down the tubes.

But this was not an unalloyed triumph for free will. Quantum mechanics replaces determinism with randomness. We aren’t predestined to go to hell; it’s all in a flip of the coin. That doesn’t make you feel any better, does it?

Quantum mechanics also had another consequence: not only did it shatter determinism, it also shattered temporal reversibility. This is the notion that the laws of physics can work backwards in time just as well as they work forwards. Before quantum mechanics, physicists were embarrassed to admit that they could not explain why time always moves forward. In the entire structure of physics, there wasn’t a single fundamental reason for time to be unidirectional. The fact that time is unidirectional was a baffling reality for physics. But quantum mechanics changed all that. (Warning: at this point I am expounding personal opinions rather than generally acknowledged truths.) For example, the final destruction of Maxwell’s Demon (an imaginary creature who violated the Second Law of Thermodynamics, thereby challenging the unidirectionality of time) was not accomplished until Leon Brilloun used quantum-mechanical arguments to finish him off.

But it’s easier to see the relationship between quantum mechanics and temporal irreversibility if you think in terms of the Uncertainty Principle. This principle establishes that information knowable about the universe is finite. Now combine this fact with the knowledge that information "draws interest". That is to say, information gained about a physical system at one time can be combined with information obtained about that system at a later time to gain even greater knowledge of the system, in a manner that exceeds the simple sum of the measured information. The longer you wait between measurements, the more "interest" (additional information) you can earn from a second measurement. This of course would permit you to gain gigantic amounts of information about the universe, thereby violating the Uncertainty Principle. The resolution to this apparent quandary lies in the fact that information "degrades" with time. If you gather information about a physical system, and then gather more information at a later time, you won’t be able to meaningfully combine the data from the two measurements because the system will have randomly changed in ways that render the combination useless.

The upshot of this is that the Uncertainty Principle establishes temporal irreversibility. Time has an unambiguous arrow defined by the necessary degradation of information arising from the Uncertainty Principle.

So what does any of this have to do with game design? Well, let me talk about temporal reversibility. Computer games permit temporal reversibility within their universes. How? Simple: you play the game for a while and reach a critical juncture. You save the game, then choose Door A. Woops, you got eaten by an orc! No problem -- just reload the game and avoid Door A the second time through. In effect, you went back in time and changed your decision.

Note that this action proves your possession of free will. If you choose path A, then one could argue that you were predestined to choose path A, but if you go back and choose path B, then there can be no argument about predestination. Temporal reversibility allows us to prove free will.

Interestingly enough, I have heard some designers mostly people with noninteractive backgrounds complain about this reloading option and suggest that the games should be designed to obviate the possibility. It would seem that some people have it in for free will.

Note further that we don’t get temporal reversibility in the real world, which means that we cannot use it to prove our free will. Falling back on the theological discussion, this suggests that temporal irreversibility is God’s kluge to cover up His decision to deny us free will, but allow us the belief that we possess it. If we could go back in time and change our decisions, then we could prove that we have free will. The fact that we can’t suggests that maybe we don’t... right?

Thus, we see theology, physics, and game design all brushing elbows on the issue of free will and determinism. Indeed, the intellectual possibilities here suggest that a merging of game design with theology could yield an exciting new field: experimental theology. I wonder if I could get an NSF grant...

As it happens, however, there is another resolution to the problem of free will versus determinism, one that embraces physics and rationalizes faith. It says that God is omnipotent with respect to process, not data. That is, God controls the universe through His laws, but not through the details. God does not dictate the position and velocity of every electron and proton in the universe; instead, He merely declares, "Let there be physics" and then allows the clockwork of the universe to run according to His laws. In an indirect way, we could say that He does control everything that happens in the universe, but it is only indirect control.

This realization provides us with the resolution of our apparent conflict between free will and determinism. God determines the principles under which the universe operates, but grants us free will to choose as we wish within that universe. He even works a little randomness into the system to insure that we aren’t automatons responding robotlike to our environments. The important point is this: God is a process-intensive designer!

And the same resolution works with the apparent conflict between plot and interactivity. If you are a data-intensive designer, then you are necessarily a deterministic one. Like some Bible-thumping fundamentalist, you insist that every single word you write must be obeyed literally by the characters in the story. The fundamentalist focusses all his beliefs in the data of the Bible rather than the processes behind it.

But if you are a process-intensive designer like God, then the characters in your universe can have free will within the confines of your laws of physics. To accomplish this, however, you must abandon the self-indulgence of direct control and instead rely on indirect control. That is, instead of specifying the data of the plotline, you must specify the processes of the dramatic conflict. Instead of defining who does what to whom, you must define how people can do various things to each other.

Perhaps you object that this is too esoteric, too indirect to allow the richness of tone that a good story requires. If so, consider what a story really communicates. A story is an instance that communicates a principle. Moby Dick is not about a whale; it is about obsession. Luke Skywalker is a lie, but the movie’s truths about growing up and facing the challenges of manhood are its real message. Stories are literally false but they embody higher truths. The instances they relate never happened, but the principles they embody are the truth that we appreciate. They are false in their data but true in their process.

Given this, consider the nature of the communication between storyteller and audience. The storyteller seeks to communicate some truth, some principle of the human condition. Rather than communicate the truth itself, he creates a particular set of circumstances that instantiate the truth he seeks to communicate. This instantiation is what he communicates to his audience. The audience then interprets the story; it induces the higher principles from the story’s details. Note, however, the indirection of this process. The storyteller seeks to communicate some truth of the human condition; the audience seeks to learn the same. Instead of just telling the principle, the storyteller translates the principle into an instantiation, then communicates the instantiation, then the audience translates the instantiation back into a principle. This is truly a roundabout way to get the job done.

Interactive storytelling differs from this process in two fundamental ways. First, the process of translating principle into instance is delegated to the computer. The storyteller retains full artistic control, but must now exercise that control at a more fundamental level. The basic process of translating principle into instance is retained, but is now performed by the computer. This of course entails considerable effort in algorithm creation. The second fundamental difference is that, because the story is generated in realtime in direct response to the player’s actions, the resultant story is customized to the needs and interests of the audience, and thereby more than makes up for any loss in polish with its greater emotional involvement.

Some may object that this is great theory, but in practice, the act of reducing storytelling to grand principles is beyond human intellectual ability. Nobody could ever handle so deeply intellectual a process, the critics cry. Yet this process-intensive style of storytelling is done all the time, and by amateurs, no less. Here’s Grandpa taking little Annie up to bed:

"Tell me a story, Grandpa!" she asks.
"OK" he replies, "Once upon a time there was a pretty little girl who had a pony..."
"Was it a white pony?" Annie interrupts.
"Oh, my, yes, it was as white as snow. It was so white that the sunlight reflected off its coat dazzled the eye. And the little girl and the pony would go riding along the beach..."
"Did they go riding in the mountains too?"
"Why yes, as a matter of fact, they did. After riding along the beach, they would ride up the green canyons, jumping over the brush and ducking under tree branches, until they came to the very top of the mountains. And there they would play at jumping over boulders..."
"I don’t like to jump."
"Well then, instead of jumping, she would let her pony graze in the rich deep grass on the mountain’s summit while she sat in the sun..."

And so the story goes on. Note that Grandpa does not respond to Annie’s interruptions with "Shuddup, kid, you’re messing up my carefully prepared plot!" He wants those interruptions, his storytelling thrives on them. Grandpa does not enter the room with a carefully planned and polished plot, all set to dazzle Annie. He comes in with basic principles of storytelling, and then he makes up the story as he goes along in response to Annie’s needs and interests. The story that he creates is his very special story, just for Annie and himself, and no other story will ever be the same. Because it is their very special story, it means more and has more emotional power than any high-tech Hollywood extravaganza. Yes, it lacks the careful plotting, the intricate development, and the glorious special effects of the Hollywood product. But its roughness is more than compensated for by its customization. Sure, Annie likes The Lion King but she treasures Annie and the White Pony.

Now, if some schmuck of an amateur storytelling Grandpa can pull that off, why can’t we big-shot professionals do the same?