What does it mean to "Challenge the Character"?

Celebrim · May 14, 2019

Tony Vargas said:
So, yes, you imagine that the rules assume perfection on the part of the DM. It's OK. That's how I see it, too. Afterall, if they're not working from that assumption, they'd have to put checks on the DM's role which would set the rules above the DM rather than vice-versa. It's maybe not the best way of saying - like I said 'trusting the DM' is a more tactful way of putting it than 'assuming perfection.'

Perhaps another way of putting it is that the rules assume the DM will have a better chance of knowing/implementing what's best for his group, specifically, than the designers would.

I think that those are all good ways to put it.

I would put it as, "The rules recognize that the problem of poor GMing cannot be fixed by the rules."

I think that there is a certain theory in some design circles that poor GMing can be fixed by having the right rules or process in place, but 5e D&D in particular radically departs from that fad.

Tony Vargas · May 14, 2019

Celebrim said:
I think that those are all good ways to put it.

I would put it as, "The rules recognize that the problem of poor GMing cannot be fixed by the rules."

That's a slightly different statement, since it makes the leap from speculating about design assumptions - to taking a specific position on game-design theory (which may or may not have informed the assumption).

I do, however, think it's fair to say that no rule can stop the GM from just changing the rules (Rule 0 in 3e wasn't so much a rule, as an acknowledgement of fact).
So, a bad (malevolent) DM could simply change any rule that got in his way. The closest a system could get to protecting players from their own DMs' malevolence would be to have many rules that might get in the way of malicious DMing, and encourage a culture of suspicion towards DMs who change/override rules.

You can see how that could never fly with 5e's DM-Empowerment mandate. So, it "assumes perfect DMing" - or rather, makes no provision for imperfect DMing. Once you make that leap of faith, though, the system can fall back on the DM as much as needed to keep it simple/intuitive/light/natural/flexible/etc as desired, without worrying so much about the mechanical nitty-gritty debates that drove us crazy earlier in the WotC era.

(Instead we get this kind of discussion to drive us crazy! Progress!)

I think that there is a certain theory in some design circles that poor GMing can be fixed by having the right rules or process in place

Sure, use an analogy, you don't have to assume perfect drivers to build safer cars, quite the contrary, you start by assuming there'll be accidents. Thus "rules can't fix poor GMing" is akin to "seat belts can't prevent accidents" - and it's not like no one said that back when there was debate on the issue, there really was a school of thought that safety features would make drivers careless and /cause/ more accidents.
Of course, an analogy with one very important difference: fatal D&D accidents are exceedingly rare. The worst that can happen is an un-fun session.
Perspective.

Hriston · May 15, 2019

5ekyu said:
Nitpick - "to the priests" did not accompany "hazardous" in the write-up in the PHB. So, for instance, if the priests' spells and efforts are tied up combating a local outbreak, they might consider casting cure spells on your scratches a lower priority than saving other people's lives - the hazard being yo those thry are helping.

Forgive me, but this interpretation seems like a lawyerly effort to screw over the players. I think it's pretty clear that hazardous assistance refers to assistance that would be hazardous to the priests themselves, not hazardous to anyone in general.

5ekyu said:
But, to be clear, given your long list of assumptions, I would boil it down to "unless there is a compelling reason not to... "

What's wrong with sticking to only the conditions of the spell or feature, and not imposing additional restrictions that the DM deems "compelling" in his/her judgement?

5ekyu said:
A referencexwas made above yo sort of "without a good reason" and to me most of my playstyle revolves around "say yes, unless you have a compelling reason to say no" and I basically set the burden on me as GM through setting, circumstance and NPC to establish "why not" instead of on the player and their PC to establish "why."

So, really, more often than not the "no" is already expected as they see "why" before they get to the " no".

This all seems good to me and sounds like it avoids mismatched expectations. If the "why" has already been established though, I wonder why you would ever get to the "no", unless I'm misunderstanding you.

Hriston · May 15, 2019

iserith said:
I can't really speak for the social contracts at anyone's table but my own. From the perspective of the rules though, that expectation does not hold up well in my view since the outcome of all action declarations are decided by the DM who is empowered to use the rules to inform his or her decision but is never beholden to them. (This necessarily includes something as simple as taking rope out of a backpack, even if this is probably too granular for most groups in a practical sense. It is an action declaration after all.)

Because of this, as a player, I have absolutely zero expectation that the things on my sheet will matter in all situations, though if the DM is consistent in his or her application of the rules and the internal logic of his or her setting, I can probably reliably predict that it will or will not matter. Sometimes I will be wrong though. If the DM is not consistent, then all bets are off. This argues for consistency in the DM's approach, whatever it may be, more than anything.

This is a more expansive interpretation of "the rules serve the DM" than I would subscribe to (e.g. I would rather change the player's background feature beforehand than override it during play), but I can accept that the social contract of many if not the majority of groups contains such an understanding and that their games are no worse for it.

pemerton · May 15, 2019

Tony Vargas said:
I think the idea here would be that the GM can insist that they don't smell anything (because there's nothing to smell), but they're free to insist that they do - so they're either hallucinating, deluded, or just teasing the guy. And, really, probably not hallucinating, but deluded, yeah, if the distinction is that hallucinations are /caused/ by something (like the ergot in the rye bread that came with your standard rations - should've sprung for the iron), while delusions are self-imposed.

Right. Which is not consistent with the suggestion that the player has total authority over what the character thinks and feels.

Elfcrusher said:
If the GM likes the idea, he runs with it. If he doesn't think his Chamberlain should smell bad (but I do hope he has a good reason, because really if the players want him to smell bad that's a great contribution) then the PCs are the only people who think he smells bad.

The players are free to have their characters act like he smells bad.

The players are free to have their players think he smells bad. But they may eventually notice that nobody else thinks he smells bad. They're free to come up with whatever narration they want to explain it. They're crazy? They suffered neurological damage in the battle with Jubilex? They all were fed some herb as kids that happened to make them extremely sensitive to the chamberlain's cologne? I don't know, but if they're creative enough to come up with the idea in the first place, I'll bet they are creative enough to come up with an explanation for why they are the only three people who seem to think he's smelly.

But they're not free to come up with the answer because he is smelly. That is, they're not free to make their perceptions non-delusional.

5ekyu said:
what the players are doing is *either* (their call as to which ) in character pranking *or* deciding that their character finds the particular smell of the target unpleasant. If its the former, it might become relevant as deceptions are not absolute. If its the latter, it would need to be played within the normal expectations for percrption established in the game.

So, no real conflicts unless the players want to define not just what they think of the target's smell but how far it goes or how loud it is.

Again, the GM - by declaring that the chamberlain doesn't stink - is able to exercise control over what beliefs and sensations the players are allowed to attribute to their PCs.

I don't think that that is all that outrageous. It's just not consistent with certain claims about the extent of player authority. The underlying point is that what a person thinks and feels is, in part, a function of the environment in which that person is located. So you can't give one author full authority over the first, and another author full authority over the second, without generating the potential for conflict.

Tony Vargas · May 15, 2019

pemerton said:
Again, the GM - by declaring that the chamberlain doesn't stink - is able to exercise control over what beliefs and sensations the players are allowed to attribute to their PCs.

Allowed to attribute without resorting to the rubric of delusion, anyway.

I don't think that that is all that outrageous. It's just not consistent with certain claims about the extent of player authority. The underlying point is that what a person thinks and feels is, in part, a function of the environment in which that person is located. So you can't give one author full authority over the first, and another author full authority over the second, without generating the potential for conflict.

That does not sound unreasonable.

Guest 6801328 · May 15, 2019

pemerton said:
But they're not free to come up with the answer because he is smelly. That is, they're not free to make their perceptions non-delusional.

I disagree. "Smelly" is a subjective term, and a player is free to declare they their character finds a certain odor offensive or not. Now, if the rules call for a saving throw to avoid an effect the dice may override their declaration ("Sure, usually you like the smell of raw sewage, but in this case it overwhelms you...") but otherwise why not let them decide what they are sensitive to, or not?

Again, the GM - by declaring that the chamberlain doesn't stink - is able to exercise control over what beliefs and sensations the players are allowed to attribute to their PCs.

As I said above, the GM's mistake here is making a declaration about how the players interpret something. (I mean, the big problem is a dysfunctional table. Either the players pulled this stunt in bad faith, or the GM is a dick for not rolling with it, or both. But that aside...) The GM should stick to describing the environment, including other characters:

"Lady Longbottom is leaning in close to the Chamberlain, whispering and laughing. She certainly doesn't seem bothered by any odor."

Are the character's delusional, or other people used to it or faking it? Something for the players to wonder about, and the GM hasn't contradicted anything they've said.

"You want to lean in close and see if you smell anything specific, without him noticing? Any particular way you are trying to achieve the latter? No? Ok, give me a perception check. Yeah, you smell traces of sweat, cologne, and maybe wine. Now give me a sleight-of-hand or deception check, your choice..."

If a player tries to declare, "But the Chamberlain *IS* smelly!" The GM can just say, "To your character, apparently."

Etc.

Again, the players may push against this. "No, I definitely smell skunk." Then we're talking delusion and/or dysfunction. If that situation actually occurs maybe somebody at the table can post here and ask for advice, but that's a matter for navigating social situations, not resolving game design philosophy.

Hriston · May 15, 2019

Celebrim said:
I think I agree with all of this. The rope is in the backpack. That has been established in the fiction by some process of play. The player has a reasonable expectation that, "I take the rope out of my backpack..." is something that should automatically succeed, and is probably the preamble to some larger proposition like, "And start tying one end around my waist." The play may expect that in some games, using the rope successfully is something that might be checked, or that the DM may require a full round of searching through his stuff to find the rope. The player probably doesn't expect, "You don't find the rope."

However, I think we both agree that the GM could say, "You don't find the rope.", if the GM has some knowledge of the fictional positioning that the player doesn't, or the player has forgotten that last week he tied the rope to a pillar at the top of the pit the party is now in, and it is logically still back there hanging down the wall. The GM may know that one of the other players handed the GM a note saying, "I steal the rope from his pack while he's sleeping.", or he may know that the Mite in area #26 stole the rope back when the PC put the backpack down while they were fighting the Steam Mephits, or that the rope was actually an illusion cast by the imp in area #43 and never existed in the first place.

The fact that we both agree that the GM could say this because he has more knowledge of the fictional positioning than the player is proof that the DM controls the fiction outside of the player. The two say the same thing. While he may agree that the player's view of the fiction ("the rope is in my backpack") prevails, he is not required to do so. Ultimately, the player can't force the DM to accept the player's view of the fiction. The player may insist that he recovered the rope, or that there was no way it could have been stolen, or that he has two ropes - and depending on the persuasiveness of the argument the GM may yield - but the GM is meant to be the judge of what is true here.

Isn't this just another way of saying it's the DM's job to keep track of this stuff? What judgement is required over whether the rope is in the backpack or not? If the DM has secret knowledge about it, then it's the DM's job to keep track of that until it's revealed through play, sure. But if it's shared knowledge by both player and DM that the rope is in the backpack, I don't see how the DM is controlling that. Let's assume this rope has been in the character's backpack since chargen. Wasn't it the player who put it there when s/he outfitted the character? To me, that, and the choices the player has made in play about how the character has manged his/her inventory since then, is what controls the fiction about whether the rope is still in the backpack when the player has his/her character reach for it.

Celebrim said:
If that isn't true for rope, then isn't it true for +5 Vorpal Swords? Surely a player could validly argue he'd enjoy the game more if his player happened to find a +5 Vorpal Sword is his backpack? Surely it's easy to imagine a player arguing this find would make the game better for everyone, and the player honestly be arguing in good faith. The player may even be correct - everyone at this table might enjoy the game better if they were less gritty and playing in a higher tier. However, ultimately, the GM still runs the game, and if the GM overrules rope or +5 vorpal swords, it's his reasons for doing so that prevail good or bad.

Maybe a player can propose to the table that they play a different game with different assumptions. They still can't control the setting.

These aren't entirely hypothetical examples. I had a DM friend of mine invite a new college aged player to his game and told him to make a third level character for 1e AD&D. The player showed up with a third level character (with multiple 18's)... and a +5 vorpal sword, wand of wonder, a ring of elemental command (fire), and a dozen other items on his character sheet. The player couldn't understand why the DM (or the rest of the players for that matter) weren't affirming his view that his character needed and perforce had these items. Why couldn't he just select whatever equipment he wanted? (To make it more ludicrous, this happened after the DM explicitly told the player before hand it was a low-magic gritty campaign.)

I don't think that it should be controversial that the player, not my friend the DM, was confused regarding the role of a player in the game, and what was or was not the DM's prerogative.

These are examples of dysfunctional play due to a mismatch in expectations about the allocation of the various roles and duties of playing the game. I don't see how they support an argument that in a game that has an intact social contract, with an expectation that the PC's inventory is at the player's disposal through his/her control of the PC, that the player doesn't have the authority to reliably have his/her PC retrieve the rope from his/her backpack.

Celebrim · May 15, 2019

Hriston said:
Isn't this just another way of saying it's the DM's job to keep track of this stuff?

Not at all. Or at least, at my tables I certainly don't keep track of the players stuff, and if the player takes something but doesn't write it down on their character sheet, I'm not at all going to overrule and decide that they have it (unless it has a particular sort of curse).

All I'm saying is that the DM, in his role as secret keeper, can and usually does have information about the fictional positioning that the player doesn't have. The DM is as it were, omniscient with regards to the imagined world. The player on the other hand, since his knowledge of the game is filtered by the secret keeper according to what he has noticed or can perceive, is acting under "fog of war". This is required to allow for the aesthetic of discovery, as it is sometimes called exploration.

What judgement is required over whether the rope is in the backpack or not?

Access to the secret knowledge, as you well understand because you go on to say...

If the DM has secret knowledge about it, then it's the DM's job to keep track of that until it's revealed through play, sure.

You aren't as confused as you think you are.

But if it's shared knowledge by both player and DM that the rope is in the backpack, I don't see how the DM is controlling that.

Your actual confusion over this is someone has introduced a false dichotomy into this discussion, and you've bought into the false dichotomy and are assuming that people like me are arguing over that false dichotomy. The question over the rope has never been whether the DM or the player controls the rope. No one set out to set up a dichotomy over who controls the rope. The claim that this dichotomy existed, only muddles the conversation and confuses people about what is being debated.

The question is over how the rope was introduced to the fiction.

I asserted that the rope was introduced to the fiction in one of two ways - by GM fiat, since the GM controls the setting and therefore can add ropes to it by fiat, or else through a process of play. For example, the rope may be in the PC's backpack because as part of the process of CharGen, the player exchanged a CharGen resource - say "gold pieces" - for a list of approved items and equipment that had approved costs associated with them. As long as the player has the rope through that established process of play, then the rope exists in the fiction somewhere (even if it is no longer in the player's backpack). Likewise, a different game might dispense entirely with the traditional equipment list mechanic, and have a process of play where the player begins each session with some number of empty equipment slots, and during the course of the session the player may announce that he's filling an equipment slot with a normal mundane transportable piece of equipment - such as a length of rope. Again, if that is the case, then the rope exists in the fiction because the player has used an established process of play to bring the rope into the fiction. While the mechanics seem a bit different from the traditional equipment list mechanic, they are actually fundamentally the same - the player exchanges some sort of limited resource for some other sort of limited resource. They differ really only in the details.

Neither is anything like the GMs ability to bring rope into the fiction. The GM can just establish that there is an entire room of rope, a whole ropemaker's guild, an entire forest covered in enchanted rope, or whatever else he likes.

Let's assume this rope has been in the character's backpack since chargen. Wasn't it the player who put it there when s/he outfitted the character? To me, that, and the choices the player has made in play about how the character has manged his/her inventory since then, is what controls the fiction about whether the rope is still in the backpack when the player has his/her character reach for it.

If we assume that the rope has been in the character's backpack since chargen, then you've constructed a circular argument. The rope is introduced by the process of play and per your constraint on the situation, no secret knowledge has effected the rope, so yes at this point the rope is by definition introduced to the fiction by the player and that choice was made by the player. But your statement is as pointless as it is circular, because it argues a point that was never in contention.

The point of contention was whether ropes in a backpack since chargen were introduced to the fiction by the same process as ropes introduced by the GM. And this rope, just wasn't. You've already conceded the important point, that the GM may have secret knowledge about the rope and he may therefore overrule the player's understanding of the fiction. He can do this because he controls the setting, as is implied and required by his job as Secret Keeper. The player can't have secret knowledge in the same way, nor may he override the GM's knowledge of the fiction by asserting that what the GM thinks about the fiction is not true. The player isn't the Secret Keeper nor is the player the Referee responsible for adjudicating the results of things.

Nor can the player introduce to the fiction anything not provided by an explicit process of play. The player can't simply declare by fiat, because he wishes it, that there is a rope in the corner of the cell. The GM can on the other hand introduce rope any time he wants by any means he wants. He doesn't need a process of play to do it. The rope is just there in the setting because the GM declared it to be so.

These are examples of dysfunctional play due to a mismatch in expectations about the allocation of the various roles and duties of playing the game.

Yes, exactly! And so, much less obviously, is a game where the player can declare without permission from the GM or without any recourse to the processes of play that a rope exists.

I don't see how they support an argument that in a game that has an intact social contract, with an expectation that the PC's inventory is at the player's disposal through his/her control of the PC, that the player doesn't have the authority to reliably have his/her PC retrieve the rope from his/her backpack.

Because you've already asserted yourself that the GM's secret knowledge could potentially override this authority! Unless you want to recant that, what you really mean is "I don't see how they support an argument that in a game that has an intact social contract, with an expectation that the PC's inventory is NORMALLY at the player's disposal through his/her control of the PC, that the player doesn't have the authority to reliably have his/her PC retrieve the rope from his/her backpack."

And yes, I agree that it normally is, but we've both agreed that there are rare exceptions to that where the GM can overrule the player because the GM has secret knowledge.

But again, this is all a red herring that someone else in the thread introduced to confuse things. No one has ever asserted that the player's inventory isn't normally within the player's control. The real question is not whether the player controls their inventory, or even whether they normally control their inventory. The real question was whether the items in a player's inventory could be declared to be there by the player's fiat, in the exact same fashion that they could declare by fiat the intention to climb a wall or attack an orc with an item in that inventor. In other words, I argued - and still argue - that while a player can by fiat declare what a PC feels, or what a PC thinks, or what a PC does, because the player had control over the PC, their PC's possessions - while they were part of the character - where still external to the PC and could not be controlled or introduced by fiat alone.

To disagree with this is to assert that these two propositions by the player are fundamentally the same:

A) I draw the +5 Holy Avenger [which my player acquired during play], and attack the Lich King.
B) I draw the +5 Holy Avenger [which I'm now introducing to the game's fiction now even though no such item formerly existed because I think it would be cool to have one], and attack the Lich King.

That is the real point of debate. The whole "who is in control of the backpack" canard was a logical fallacy introduced to disguise what I would think is a rather unpopular claim that 'B' and 'A' are actually the same thing for what it is. And since you've already agreed that one example is "dysfunctional play due to a mismatch in expectations about the allocation of the various roles and duties of playing the game", then I suspect you and I really don't have much to disagree over.

Celebrim · May 15, 2019

Elfcrusher said:
I disagree. "Smelly" is a subjective term, and a player is free to declare they their character finds a certain odor offensive or not.

I agree.

The smelly chamberlain example is just the latest example of attempt to assert that the boundaries of the PC extend to encompass all that the PC can observe or think on.

One wonders if the person making these claims believes their own person extends to encompass all that they can observe or think on?

I really have a hard time taking these arguments seriously, as I think they are less serious arguments than attempts to justify a process of play that includes a gentlemen's agreement over what different participants can introduce to the fiction in an effort to improve the game - something I think that is neither justified by these red herrings nor which needs to be justified. It's not badwrongfun to cooperate together. Go ahead, especially if you have nigh unto perfect knowledge of what everyone else at the table enjoys. Under such conditions, well why not?

But, as far as the example goes, consider the following:

The GM introduces a Chamberlain wearing costly perfumes.

The PC is, by virtue of their fiat control of their character free to assert all of the following:

1) They find the costly perfumes attractive and would like to inquire where they could purchase themselves.
2) They want to pretend that they find the costly perfumes attractive and inquire where they could purchase some themselves.
3) They find the odor offensive, but wish to pretend that they do not to avoid offending the Chamberlain.
4) They find the odor offensive, and wish to mock the Chamberlain regarding his perfumes, either to deliberately enrage the Chamberlain or make a fool of him in front of the court (or both).
5) They don't find the odor offensive, but wish to mock the Chamberlain regarding his perfumes anyway.

Likewise, if the GM introduces a Chamberlain which he describes as having strong body odor, by virtue of the player's fiat control over the PC, they may propose all of the following.

1) They find the body order attractive and would like to compliment the Chamberlain on his manly odor.
2) They want to pretend that they find the body odor attractive and compliment the Chamberlain on his manly odor.
3) They find the odor offensive, but wish to pretend that they do not to avoid offending the Chamberlain.
4) They find the odor offensive, and wish to mock the Chamberlain regarding his body odor, either to deliberately enrage the Chamberlain or make a fool of him in front of the court (or both).
5) They don't find the odor offensive, but wish to mock the Chamberlain regarding his body odor anyway.

Further, the GM could introduce a Chamberlain with no noticeable odor whatsoever, and yet by virtue of the player's fiat control over the PC, the player could still propose:

1) They find the Chamberlain's smell attractive, as a false to facts of the fiction assertion regarding the odor of the Chamberlain.
2) They don't find the Chamberlain's smell attractive, as a false to facts of the fiction assertion regarding the odor of the Chamberlain.
3) In combination of neither or either of the above, that they wish to insult the Chamberlain regarding his smell, in hopes of enraging the Chamberlain or making him seem foolish in the eyes of the court.

None of these assertions need to be justified. The player is declaring things about his character's beliefs, feelings, and actions. He may or may not have good justification for those beliefs, feelings, and actions, but he doesn't have to justify them. He's just playing his character.

However, as soon as the player tries to declare something that is not about his PC's beliefs, feelings, or actions, but rather about the beliefs, feelings, or actions of NPCs or the existence of novel things in the fiction, then he's not playing his character. I can't believe I'm saying that, because I would have thought it was obvious and axiomatic, but here we are.

Now, depending on the player character's social skills, courses of action regarding the Chamberlain's odor such as attempting to make a fool of him in front of the court might have a chance of success. The odds of success will very much depend on the perceptions of the NPCs. If it is the case that the Chamberlain's odor is not much commented on in the court, the player's proposed course of action would be much more difficult than if the GM decides that Chamberlain's odor is already perceived by the court as being obnoxious and everyone is just afraid to say anything about it. The clever player may in fact have perceived by some means that this is true, while a creative player may be banking on it being true or something the GM finds plausible.

What is not the case is that the PC can propose that since his player finds Chamberlain's odor offensive, that the NPCs of the court find it offensive - and this is especially the case if the GM does not establish that such an odor exists and in fact notes that the odor is not particularly notable nor would it normally be found offensive at all. It's beyond the bounds of playing your PC to make declarations about what exists in the environment or how NPCs think and behave.

Real people can't cause smells to come into being that other people experience just by imagining them. Neither can a PC acting in the fiction cause a smell to come into existence by imagining it. Perhaps a heroically good orator could convince a court by the power of suggestion that the Chamberlain smells despite their being no significant odor present, but in this case he's by the power of his descriptive rhetoric introducing into the fiction a belief that the Chamberlain smells and doing that through a process of play. Or a wizard PC might actually magically create an odor to attack to the Chamberlain to embarrass him provided he had some character ability that allowed the player to assert such a narrative device. But all of that is playing your character. Claiming that your character thinks the Chamberlain smells, and therefore perforce the Chamberlain does smell is not playing your character because implicitly it is NPCs doing the smelling. You can no more control what the NPCs think by fiat than the GM can control what your PC thinks by fiat.

On that note, the GM cannot do the following:

a) Assert that since the Chamberlain has body odor, you find him offensive. Even if the body odor is so bad that it causes an automatic physical reaction, you ought not say that the PC finds that offensive, only that it causes him to vomit unless he passes a fortitude save (or whatever). If he passes the fortitude save, he's free to explain that he likes the smell of body odor, so this was no big deal. Heck, the player may hypothetically be playing a talking dog that finds the smell of dirty socks the best thing in the world. But even if he is, the player gets to decide that - not you. (Heck, if the player wants to establish in the fiction that he finds body odor attractive, as a GM I'd probably decide to hence forth mechanically support that just because it's amusing.)
b) Assert that since the Chamberlain is wearing expensive perfumes, you find the perfumes attractive. Even if the perfumes are magical, so that they cause an automatic physical reaction impairing judgment as if the PC had just downed a pair of Long Island Iced Teas on an empty stomach, that's still a matter of process of play to establish if the PC is so impaired that it overrides the players normal control over the character, and has nothing to do with the perfumes attractiveness.

As I said above, the GM's mistake here is making a declaration about how the players interpret something. (I mean, the big problem is a dysfunctional table. Either the players pulled this stunt in bad faith, or the GM is a dick for not rolling with it, or both. But that aside...)

Agreed. I've had a lot of problem players over 30 years of play, but this hypothetical where the player insists that they believe some false to facts thing and therefore everyone else ought to as well has never come up. I'm pretty sure I've had players insist on false to facts play, but only because they were gonzo players that wanted to play someone who was delusional or weird, usually out of misguided attempts to attract the spotlight to their PC. Sometimes it was even believably in character for them to be delusional and weird. They still didn't insist that the NPC's and other PC's present had to believe the same thing. How we've had the thread derailed over endlessly pointing out that no, ascribing traits to other characters or things in the setting in contrast to the established fictional positioning or introducing things which were novel to the fictional positioning did not constitute playing your PC. It might even be something that was allowed, but if it allowed, it still wasn't playing your PC but rather shared narrative control that arose from something other than the right to play your PC.