View Full Version : Omniscience, Causality, and Gaming

2011-08-09, 02:32 PM
Inspired by a discussion of Divination in 3.5 (http://www.giantitp.com/forums/showthread.php?t=210772), I thought I'd open the question to the larger gaming context.

In short, for systems with Gods or Divination, how do you reconcile dice-rolling with foreknowledge?

IMHO, it is a bit of a cop-out to go with any of the "Divination Is Useless" routes in which die rolling makes foreknowledge of any event at the whim of the DM. This is an easy answer, to be sure, but it proves too much as every event in most RPGs is at least theoretically subject to one or more die rolls. In such a world, what good is Divination of any kind, and if Divination doesn't actually Divine anything well, why is it there?

Note that even the "Reply Hazy" approach in which Divination only reveals broad and subjective answers is a flavor of the above style of foreknowledge. In each case the DM is deciding how hazy to make the answer, and this is frequently bounded by "usefulness to the plot."

Of course, the other side of the coin -- perfect knowledge -- can result in the DM removing suspense from the game by providing predestination. Predestination always feels like Railroading when it happens to the PCs, even if the predestined event is determined by an immediate die roll. Worse, when such divination is easy to use, adventures can become games of 20 Questions; a bad result in my book.

So far, I haven't run into this problem myself due to careful selection of game systems and power levels but it is definitely something worth considering. As a gut response, I'd probably go with the D&D4 approach to Divination -- limited access to foreknowledge, with most foreknowledge Rituals answering questions in the weal/woe format.

2011-08-09, 02:50 PM
I think that thread tends to assume the only questions worth asking are "where's the BBEG, what's he doing, what are his defenses, and what information do I need to teleport in and kill him tomorrow?" A number of people in that thread certainly acted like if you can't do that, then spells in D&D like Contact Other Plane are worthless. In actuality, there's a lot of useful information you can gather with such spells that doesn't involve the above details (such as looking for an artifact or the like).

That said, in any game I ran, I probably would have deities capable of seeing details in the future. Hazy images maybe, but that's it. That makes it a lot easier to deal with. More powerful divination might work well in a book, but it would be hard to manage in a game. Well, I'd do that or have the act of asking potentially change things -- the future is sensitive to measurement.

2011-08-09, 02:51 PM
- edit -

I didn't realize how off topic I was when I wrote this. Sorry about that. Original message spoilered below. It addresses how I feel about divination in general, but doesn't go anywhere near divination in spite of what the dice may say.

I have a couple tricks up my sleeve here.

First off, nobody in the game world has perfect knowledge. Whenever the players gain someone else's knowledge that's person's confusion and uncertainty is included. I don't think this is a copout because it's how I run everything.

For example, I did a murder mystery several years ago. The players talked to the NPCs and collected clues. When they tried to put the clues together they politely informed me that I gave them the wrong info. I looked over it and told them I gave out exactly what I'd intended. Then they yelled at me for making an unsolvable puzzle. When I explained that the NPCs giving the clues lacked perfect knowledge, the players stopped trying to assemble the clues like pieces of a logic puzzle. Then they treated the mystery like a social puzzle so they could see who was lying and the game carried on as normal.

Given that I treat all information in that manner, I don't think I have a choice but to be consistent and treat divination the same. Obviously it depends on the type of divination though. If they get to watch an event through an NPC's eyes, they get different information than if they ask a god for answers.

The other trick is to give them puzzles with more than one variable to solve. The mystery above wouldn't have worked with divination present because there was only one unknown - whodunnit. Instead, run several plots at once. Now when you drop a body in the fountain at the center of town, the players don't know which plot just got a clue. Sorting the data you give them so that they can apply the clue becomes a puzzle in and of itself. When you're giving the players that much information to sort out, giving them a couple freebies via divination doesn't hurt your mystery in the slightest.

2011-08-09, 02:58 PM
Divination is tricky, but I think the best way is to make all visions/omens very vague and open to interpretation. Making a bit of an art to discerning the future from the message recieved.

You won't see a band of assassins break into your noble lords mansion. You might however see your lords heraldic weapon fall from a shelf and crash onto the ground, suggesting that perhaps he is in danger... or he's going to die and the repercussion will destroy his family... or his political influence is vanishing. Or perhaps that choosing to stay with him will spell his end?

Asking if the city you protect will fall if you leave it might net you a vision where you see the the banner of the hostile undefeated warlord flutter over it. Which might very well mean that the city will be undefeated (thus deserving the undefeated banner more than him).

In other words. Divinations should provide riddle-like messages that it's up to the players to reason through, interpret and choose their actions from. No straight answers to anything, never being told in clear words what will happen and definantely no yes or no.
Keeping a very mystic flair over the entire arts in all of it's various forms.

2011-08-09, 03:12 PM
In short, for systems with Gods or Divination, how do you reconcile dice-rolling with foreknowledge?

You can't, really, though you can try various workarounds like the many-worlds approach. Probability and predestination are fundamentally different ways of seeing the world: probability says there are multiple possible futures, predestination says there's only one.

This doesn't mean that divination is useless - if you look at most D&D divination spells, their primary function is to give information about the past or the present, not the future.

2011-08-09, 05:15 PM
Let player make appropriate actions post-die roll. That is, after you know the result tell him what he found out and figure out what's different. This is how we do it. Not perfect, to be sure, but no DM can model all the complex interactions within a world anywhere near sufficiently anyways so that doesn't take much in terms of willing suspension of disbelief. It gives players the knowledge their foreknowledge was supposed to grant them and get to prepare appropriately without you having to, out of game, predict the future or skip die rolls.

2011-08-09, 08:13 PM
I use a different model depending on the source of the information.

One example I've run into is, I've done a lot of games involving time travel. Here divination is just a quick walk into the future, seeing what its like, and returning. The rule of thumb I use for that is:

Tthe future you see is what you'd get assuming roughly consistent behavior on the part of the PCs combined with no exceptional behaviors or situations (i.e. no moments of particular brilliance, no random Deck of Many Things draws, etc).

So you get an answer - its what you see. The problem is, the answer isn't stable.

The stability depends on whether the thing you're asking about is microscopic or macroscopic. Microscopic things (what will I draw in tomorrow's poker tournament?) are very unstable, and the best divinations and most powerful gods can't accurately predict a single outcome beyond a few hours time (they can get the distribution of outcomes, and the most powerful beings can get a conditional tree of outcomes so they can pick the one they like, but the second they tell the diviner the information things have changed). Macroscopic things (will we win the war?) are pretty stable on a scale up to a year or even decades, but beyond that they also become chaotic.

Furthermore, if someone directly changes their actions as a result of the future information and thereby changes the circumstances of it, the information is immediately invalidated. So if someone asked 'will I pass my next save against poison?' got a 'no' result, asked 'how about my second save?', and got a 'yes' result, and then immediately drank a vial of drow sleeping poison to burn off the 'no', the second 'yes' would be invalidated.

Now, another source of future information would be from beings associated with fate. In that case, asking sets the answer. For instance, you could ask 'what will I draw in the poker tournament tomorrow?', hear 'high card', and decide to cheat by fixing the deck, bribing the dealer, whatever. If need be, some ridiculously unlikely thing will occur to make sure that you do indeed draw high card. Someone else will cheat, cards will get mixed up in transport, ink will flake off the card to make it what fate decrees, etc. On seeing it, people may well declaim 'how did that happen?!' - its basically the fate manipulator guaranteeing the truth of their prediction, using whatever powers they have to control the world.

In practice, it'd go something like this:

- Player asks a divination about, e.g., whether they'll pass their next save against poison.
- If they ask someone who can see the future through other methods (observation, prediction, etc), I'll roll the die and give them the number. If the next save happens within a few hours, they get the die result I rolled, otherwise they have to roll again. If they directly change their actions because of the information they receive, the prediction is discarded.
- If they ask a being of fate, the answer is determined, and then it overrides the die roll regardless of how far in the future, what the person does, etc.

2011-08-09, 09:14 PM
As one of my gaming buddies likes to say, "always in motion the future is." In other words, stuff happens, things can change.

2011-08-09, 09:32 PM
In short, for systems with Gods or Divination, how do you reconcile dice-rolling with foreknowledge?

I eliminate omniscience. I guess ultimately I started designing my gods by grappling with this question, pinning down the simple answer "They can't tell you because they don't know for sure", and then figuring out what kind of gods would lack thorough foreknowledge. I like my gods a lot now, and they're more playable than most are. My world uses lots of divination and the gods are extraordinarily chatty by D&D standards, but all I have to do is say "The goddess tells you this is her best guess."

2011-08-09, 10:47 PM
Fundamentally, prophecy is a form of reverse causality (the prophecy is caused by the future event as well as past ones), and thus cannot be implemented fully in a universe with a strict arrow of time*.

It's the same basic problem as trying to fit self-consistent time loops into a game.

*Strict arrow of time means that future events cannot affect past ones. All game universes have one, since the DM doesn't know what will happen next session (and can't go back in time to change a prophecy based on what actually happened). Books, movies, and other non-interactive media don't, since the fiction is constructed as a whole. RL also doesn't have one, ironically enough.

2011-08-10, 01:26 AM
*Strict arrow of time means that future events cannot affect past ones. All game universes have one, since the DM doesn't know what will happen next session (and can't go back in time to change a prophecy based on what actually happened). Books, movies, and other non-interactive media don't, since the fiction is constructed as a whole. RL also doesn't have one, ironically enough.

You could do short loops in games where one person can temporarily take control of the narrative. They'd basically completely encapsulate the loop in their narration.

For that matter, you can do iterative convergence sorts of things to get self-consistent loops (if players break the loop, they have to redo everything until they get it right), but thats really annoying to play.

Jay R
2011-08-10, 10:10 AM
Prophecy is a violation of the law of cause and effect. There are several ways to handle it.

1. Using knowledge fo the present that the PCs don't have. If I know what the BBEG is planning, and know that nobody can reach him in time to stop him, I can predict that, say, the king will die in three days.

2. Limited prophecy: some version of "Reply hazy. Ask again later."

3. Prophecy is what would have if the prophecy hadn't been made, and allows changes caused by those who know the prophecy.

4. Prophecies are vague: "If you attack the Greeks, you will destroy a great empire." But will it be the Greek empire or your own?

5. The Railroad of Fate. The Fates, the Gods, the story-teller, or the DM will make the prophecy come true, using all your attempts to prevent it as tools. Done well, this is a great story of Fate (Oedipus). Done poorly, your characters will accuse of of railroading, which is exactly what a prophecy is.

Redshirt Army
2011-08-10, 10:29 AM
I haven't used this in a game yet, but I had an idea that when someone attempts to figure out the future, I just pre-roll the dice for it.


Player: Will the BBEG succumb to Black Lotus Extract?
DM: <Rolls Fortitude Save> No, he won't.

Keep in mind that players are special, and that any divination that forsees the future isn't foolproof. If the PC's later use magic to lower the BBEG's constitution, it's possible that he will, in fact, succumb to said poison - because the PC's changed the future with their foreknowledge. This method does force the players to tell you their future plans, but as a DM, you should be able to avoid abusing that to the players detriment.

2011-08-10, 10:48 AM
I like the Frank Herbert prophecy/foreknowledge premise: Even just viewing the future changes it.

Totally Guy
2011-08-10, 11:13 AM
I like the way Burning Wheel handles prophecy. You can in fact play a prophet and have your prophecies mean something.

But first I've got to talk about Beliefs. You have a number of beliefs, usually 3, and you are rewarded by the system for acting on them or against them. If you have a belief, say: "My grudge with Jasper Black must be fulfilled". When you take a step towards making Jasper's life miserable you are rewarded. You can gain a slightly bigger reward for either fulfilling or dramatically breaking the belief. You could fulfill it by pushing him of a cliff. You could break it by saving his life. But not both! :smalltongue: That's the way the game works, you follow beliefs and are challenged and refined by how you interact with them.

A character that can make prophecies do so by telling the subject of their destiny and rolling the dice. If they succeed then one of their own beliefs changes to the prophecy as does one of the subject's.

So all of a sudden, "I am the true king and I will prove it by reclaiming my sword from the lake" becomes a belief. So the character can then go on to pursue it, and fulfill it or break it.

The prophet also has the belief, "Arthur is the true king..." so the prophet also has a big stake in the situation as he or she is also rewarded for guiding that character to their destiny or arranging events so that the subject will face it.

There is no guarantee whether the prophecised thing will happen or not but the you can be certain that the prophecy will be a driving force within the game.

The prophet can only do so many of these as they cannot have more than 3 beliefs. And if the prophet's beliefs change the subject is also free to be released from the prophesy.

In play we had a character who was questing for his heirloom polearm. After killing an innocent man in anger after being thwarted from this goal his companion, an elf, was mad at him. The elf (another player) asked him what the polearm was worth to him, asked him what he would give up for it. The elf placed upon him a prophecy that his own polearm would kill him.

It did. He realised he'd betrayed every one of his honours in service of getting it back. When he had it he discovered that now he truly had nothing.

2011-08-10, 11:26 AM
So all of a sudden, "I am the true king and I will prove it by reclaiming my sword from the lake" becomes a belief. So the character can then go on to pursue it, and fulfill it or break it.
Listen, strange women lyin' in ponds distributin' swords is no basis for a system of government. Supreme executive power derives from a mandate from the masses, not from some farcical aquatic ceremony.

2011-08-10, 12:07 PM
In short, for systems with Gods or Divination, how do you reconcile dice-rolling with foreknowledge?
With probability?

If the future is not predestined, what the Gods have is not knowledge of what will happen but knowledge of the likelihood that various events may happen.

Such information can still be quite useful to characters and players

In some circumstances, the probability may be 0 or 1, and a deity will know this and can communicate it to the players, but it seems that those situations are never what these discussions are about.

A final option is to make divination-type spells and effects not truly subject to player control: a character may seek to divine where the BBEG will strike next, but instead, TPTB (The Powers That Be) give him a vision of the volcano that is going to erupt by the end of the week and destroy a nearby city.

I like to think of this as TPTB making a true exercise of their much-greater (if not omniscient) knowledge: "Enough of your petty inquiries about trivial events. Here's something really important!" (While not necessarily railroading the party, this sort of thing could at least let them know where the train station is. Obdurate players will still insist on walking the other direction.)

2011-08-10, 01:14 PM
Roll it and say "that's what'll happen" and if they don't go out of their way to change something, that's what happens.

2011-08-10, 01:58 PM
I take a probabilistic approach to my game universes. For any given situation, there's a variety of potential outcomes, with some being more or less likely. However, not just anything can happen - while any possible outcome may happen, context may render many options, even all but one, impossible.

However, when there really is only one or two possible outcomes, it's often so obvious that you shouldn't need to be a genius to notice it. For example, if you're pinned under a mountain and didn't tell anyone where you were going, you will die.

An entity approaching "omnicience" will be cognizant of more different possibilities, how probable they are, how they interact and link with each other, and so on. The problems start when trying to parse all this information to simple sentences or prophecies - any actual analysis would be as complicated as quantum physics. You just... don't create summaries that are both accurate and sensible to a layman from those premises.

Jay R
2011-08-10, 02:38 PM
I bumped into a quote years ago, but don't remember where:

"I don't believe in a fate that happens no matter how you act. I do believe in a fate that happens unless you act."

2011-08-10, 10:48 PM
I bumped into a quote years ago, but don't remember where:

"I don't believe in a fate that happens no matter how you act. I do believe in a fate that happens unless you act."

Then you lose the whole Greek Tragedy thing.

OTOH, D&D probably isn't meant for Tragedies in the first place.

2011-08-11, 04:21 PM
Just make divination exactly like it is in real life, and even in myth: incredibly vague symbolic statements that the listener interprets however they like. If they interpret the meaning correctly, it's destiny. If they interpret it incorrectly, it's dramatic irony. Whatever happens, it's a good story, and you can't prove that the divination was incorrect. This is why astrology is still a business.

2011-08-14, 09:21 PM
I prefer the self-consistent route.

One interesting application of prophecy is this:
What will be the answer to this problem that I will be writing down on this piece of paper?

You then proceed to check the answer you saw in the prophecy and then if it is right, you write it down onto the piece of paper in question. Otherwise, you don't.
Hence, the prophecy will only deliver correct answers.

This is essentially a time-travel-problem-solver.