holmes's D&D excerpt: probability

"A final word to the Dungeon Master from the authors. These rules are intended as guidelines. No two Dungeon Masters run their dungeons quite the same way, as anyone who has learned the game with one group and then transferred to another can easily attest. You are sure to encounter situations not covered by these rules. Improvise. Agree on a probability that an event will occur and convert it into a die roll - roll the number and see what happens! The game is intended to be fun and the rules modified if the players desire. Do not hesitate to invent, create, and experiment with new ideas. Imagination is the key to a good game."

-Dr. Holmes's parting words, page 41, 1979.

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Michael Miller responded:

Am I wrong to see this not as Rule Zero, but instead as "giving permission" to engage in Lumpley Principle-style group consensus of game system?

I'm not saying it was ever interpreted that way at the time, but that seems to me to be what the words are saying.

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I responded:

​The reason I think you're right, +Michael Miller, and the reason I think +Christopher Weeks reference to the Advanced Fuckery chapter in AW is a keen observation, is that the "rules" that Holmes seems to be pointing to here are the rules of probability.

He's not making a blanket statement that players should do whatever they want to have a good time. He's talking specifically about either inventing probability for moments not anticipated by the rules he's laid out or shifting the probabilities to suit your game, because in D&D as he has presented it, the game world is set up as a set of probabilities. Whether or not a door is locked, whether or not wandering monsters come by, whether or not you spot a secret door, whether or not you hit a monster or are hit in return - they are all reduced to a percentage chance which can be rolled for. When you play with one dungeon master or another, the particulars of their world are shaped by those percentages (and established rules about how often and under what condition those probabilities are engaged).

So to create a new probability for a new occurrence in Holmes's D&D is very much like creating a new move in the Bakers' AW, it changes how the characters and the rules of the world interact. And as the Bakers say go forth and create custom moves that further customize your particular Apocalypse World, so Holmes says go forth and create custom probabilities to customize your particular fantasy worlds.

At least, that's the way I currently see it.