"Chekhov's Gun is generally regarded as a brilliant principle for writing tight narrative. The Russian playwright Anton Chekhov wrote:
"If in the first act you have hung a pistol on the wall, then in the following one it should be fired.
"He elaborates that if you don't plan to fire your firearm in a subsequent act, then it doesn't belong in your story, and you should remove it entirely.
"The widely accepted interpretation is that nothing should be present in your story unless it's serving some critical narrative purpose. Judicious application of Chekhov's Gun can rid your story of elements that aren't doing anything for you."
Dungeons & Dragons is NOT literature. It's not a story designed for a reader; it's not intended to produce a theme or an object the audience needs to grasp. It doesn't possess an "audience." D&D is a game. It's intended to be played by participants in a setting that in no way seeks to provide a model for behaviour or an ideology, belief or virtuous template. Therefore, it's the antithesis of Chekhov and every form of narrative writing that exists ... particularly as it isn't being written, it isn't being invented by a single voice and there's no editor to decide which fair action in the game ought to be taken. The guns can exist without being fired, the adventures can exist without being pursued. There is no dramatic structure that need be recognized, no necessary fall, no certainty of resolution and no single point of climax.
Yet there are all these things in a pre-written module-adventure. There have to be ... because the narrative is a finite piece of writing, where everything in it is assumed to have a purpose, even if it's to waste the players' time until the next part of the narrative is met.
With a momentum-rich infinite game, ten threads of possible action — ten Chekhov guns — can be invented and provided for the players in the first ten minutes, none of which ever need to go off for the game to function and move forward. In the ten minutes after than, we can introduce ten more, and then ten more and ten more again. The players can reach out and fire whatever gun pleases them; there is no right gun and no wrong one. There are certainly no necessary guns.
However, once a gun has been chosen and fired, we're off to the races as far as DMing goes. The direction and angle of the bullet, once put in motion, perpetuates a series of events that, once enacted, cannot be undone. Every action has consequences and the consequences are final; but the consequences produce opportunities, littering guns everywhere for the players to take up as they will and evoke new, desired consequences according to their proclivity.
The tendency is to read the above and suppose that this shooting of guns and creation of consequences accords itself to ONE NARRATIVE. It does not! No more so than my writings here create consequences for my workplace activities, or the visits of my grandchild, or the next venture I choose to explore, or any of a hundred activities I might participate in over the next year. My fist fight with you at a bar has a set of consequences, but these don't affect the discourse I have afterwards as I describe the events to my partner. Her reaction is an entirely different set of consequences.
In the novel The Three Musketeers, D'Artagnan inadvertantly annoys and obtains a duel with three separate men in three separate instances, to be fought one after another. Because it is a novel, the separate men naturally know each other, creating the humour of D'Artagnan happening to insult three men who are close friends and companions.
In D&D, the same result could happen, except because there is no novel, the three men need not know each other at all; there is no motivation to assure that our player character makes a single friend of the three challenged men; and the consequences to befall the character depends on how the character deals with the odd situation. D'Artagnan, in short, is not required by a narrative to like musketeers, to want to be a musketeer or to refrain from killing musketeers. Such matters are left entirely up to the player. There is no writer to say different.
All this leaves us with the nagging difficulty of how to make guns of the Chekhov variety? How, dear Alexis, do we create opportunities for the players to make choices upon? And how, for the love of all that's decent, do we decide what the consequences are when a player does something?
25 or 30 thousand words and we've at last arrived at the crux of everything: "I want to be a DM; how do I know what to do?"
I'll try to answer that question.
I need a little more time to think about it.