SteveC
Doing the best imitation of myself
This kind of a conversation is such a basic thing that I suspect that the core issue is that not everyone is really talking about the same thing, or using even a remotely similar definition of arbitrary.
Of course the GM makes arbitrary decisions: from the basics "what rules system are we using?" or "what module am I running?" to more tactical ones like how and where monsters are placed, or how NPCs react to what characters say to the esoteric questions players have about the game or what they can do.
Everything that is in an RPG session in a traditional RPG like D&D is there by the GM's will. There are other games, like Fate, where the players have agency themselves to place things in the campaign, but if we're talking meat and potatoes D&D, it's the GM (err, the DM, I mean...)
Now many GMs like to establish the way the game situation starts, and then play to that as strictly as possible without changing things that are written. I think of these folks as Deist GMs but I think most people would call them strict sandboxers or something similar. I think that's what's being discussed here as non-arbitrary.
But the thing is, even the strict sandbox GMs are still entirely arbitrary in that they at their game's "cosmic watchmaker" (oh, there I am with that Deist analogy again
).
So with that said, even though every GM is arbitrary, some are far more arbitrary than others, which is where we get into arguments about railroading or providing the illusion of choice, which are very meaningful discussions in their own right. And all of that is just my entirely arbitrary opinion, of course
.
Of course the GM makes arbitrary decisions: from the basics "what rules system are we using?" or "what module am I running?" to more tactical ones like how and where monsters are placed, or how NPCs react to what characters say to the esoteric questions players have about the game or what they can do.
Everything that is in an RPG session in a traditional RPG like D&D is there by the GM's will. There are other games, like Fate, where the players have agency themselves to place things in the campaign, but if we're talking meat and potatoes D&D, it's the GM (err, the DM, I mean...)
Now many GMs like to establish the way the game situation starts, and then play to that as strictly as possible without changing things that are written. I think of these folks as Deist GMs but I think most people would call them strict sandboxers or something similar. I think that's what's being discussed here as non-arbitrary.
But the thing is, even the strict sandbox GMs are still entirely arbitrary in that they at their game's "cosmic watchmaker" (oh, there I am with that Deist analogy again

So with that said, even though every GM is arbitrary, some are far more arbitrary than others, which is where we get into arguments about railroading or providing the illusion of choice, which are very meaningful discussions in their own right. And all of that is just my entirely arbitrary opinion, of course
