To me, it seems to have its origin in a reflexive hostility to meta-game devices and to just letting players play what they think counts, and so the sort of stuff that would be handled at the meta-level in a game like DitV or Burning Wheel is instead made part of the fiction and the setting itself.
Any time you're going to characterize something as "reflexive hostility," you're not giving it enough credit. It's an overly simplistic dismissal, and it reads very much like "I don't want to bother trying to understand what people like about this, it's just something I can dismiss as something overly emotional."
Like, instead of a player saying, "My PC wants vengeance, and won't stop even if it means a few innocents have to suffer", s/he has to say, "My PC thinks that vengeance is good, and wants to persuade everyone else of the same thing so that when vengeance is delivered I won't end up being labelled evil."
I don't know where you're given the impression that she "has to" make that specific claim. The player can choose whatever belief she wants her PC to believe about those actions. The PC can view it as good, or as evil, or as something restoring the balance, or as an edict of order, or as something she is doing to express her personal desires and nothing else, or whatever. What's important for PS is that, if the player wants to use this as a central character hook, the vengeance isn't just her personal vendetta, but a principle that extends beyond her circumstances, a conviction that defines how she views the multiverse, a belief about how the rest of reality should be. Her vengeance becomes a belief, not just a goal. For such a PC, I'd probably recommend the Mercykillers, who could frame her vengeance in terms of achieving a just world, and thus her personal vendetta of vengeance becomes an expression of how she thinks the world should work: that those who do wrong get punished. The Mercykillers don't speak in terms of good and evil, they speak in terms of just and unjust. Whether the rest of the multiverse dubs it good or evil is not as relevant.
And if such a character's story is a success, whatever her alignment, she will be seen as a person who exercised justice, an exemplar of that ideal that others should strive to achieve, and thus create a world that her vengeance has objectively made more just -- whatever triggered her vengeance will not be something others seek to do, as the belief in justice that permeates the multiverse after the PC's actions are complete creates a more just reality.
pemerton said:
If it makes no difference being labelled good or evil, then why would anyone set about trying to change the reference of those labels?
I also don't understand your fiend examples. For instance, I don't see why the argument run by your amnizu isn't already available to her.
Maybe they WANT it to matter! Not everyone is content with the prevailing belief that evil is a valid life choice. Maybe it matters TO THEM. If they believe that no one should label their thirst for vengeance evil, they can change the definition of evil. Maybe they've got an issue with the current context where pure hedonism is evil and restraint is good and they don't agree with that, they'd want to flip it, because that's what they believe to be true. Just because good and evil are both valid choices according to the planes at large doesn't mean that the PC shares this philosophy necessarily. Though given the conflicts presented in the actual PS material, most of the setting is largely concerned with other debates. But, hell, I'm sure there's Mercykillers out there who believe that the principle of Forgiveness that Good creatures (as the planes currently know them) exhibit should cosign them to Hell instead, and that's fine, they can believe that, and get the multiverse to believe it, too, and thus re-define what Good means (it no longer includes forgiveness, after this PC gets her way!).
The arguments are available to anyone, PS just presents a starting-state in the setting where that amnizu's arguments about torture being the truth of existence aren't prevalent. Given that it starts from a D&D baseline, that shouldn't be too shocking -- PS wants its baseline to be broadly recognizable to D&D players, where devils are lawful evil. So PS presents a setting consistent with that, and also presents a setting in which that is something the PC's can change if they want. Why they would want to...*shrug*. Up to those PC's, really. Our Mercykiller might believe that torture, as a element of punishment, fits Justice, and further defines Justice as Good, and so might find that amnizu to be an ally for her cause! OR she might believe that torture is something that is never justified, and so perpetrators are always further from the Justice she defines as Good, and so might want to slay/convert that amnizu. One thing's for sure: it would be an interesting scene to play through!
pemerton said:
For instance, the whole emphasis on "belief entails truth" shifts the emphasis from making hard choices in play, and living with them and their consequences, to making choices easy rather than hard by making it true, by fiat, that the choice really was right.
So by that definition, it is an easy choice to, say, offer your child up as a sacrifice to Moloch because you believe it is right to do so. Or to obey a suicidal command from your superior because you believe that this something that is right. Your definition takes for granted the concept that doing the right thing -- the thing you believe in -- is the same as doing the easy thing.
It furthermore presumes that your definition of the right thing is not challenged -- that people are not telling you that you don't need to offer up your child or obey those suicidal commands, that there aren't competing viewpoints one might embrace. That there are no such things as antagonists with competing beliefs.
I don't think I need to point out the gaping error there any further.
pemerton said:
The factions, as "philosophers with clubs", strike me as incredibly cartoony - they live in a world that they know to be nothing but a reflection of belief, including in its value dimensions, and yet they devote all this effort to promulgating particular values. Why?
They want to define the possibility space of belief, to have the multiverse actually work according to their understanding of how it does or should work, to have no dissent or competing beliefs that threaten their own. They want power over the hearts and minds of everyone in creation, to have people believe in their faction's ideals the way people believe at the outset of play that torture is evil and that gods exist and that there is a plane of Bytopia. The PC's are the ones that accomplish some major part of this.
pemerton said:
I have no idea, then, what you mean by "ambiguous morality".
Just as I said, that it is not clear if an action is good or evil. To kill a man who wants to die and who you believe deserves to die, or not and not be a murder, is to choose between two things largely regarded as morally good: either I am not a murderer (which is a virtuous thing!), or I kill someone who deserves it and is asking for it (another virtuous thing!). I cannot have them both, but both are virtuous things, so either choice I make, I am the Good Guy. "Shades of grey" means, to me, that the choices are between two things where it is not clear if any of them are really virtuous at all. I don't kill him, so I'm not a murder, BUT he also kills a bunch of neighborhood children and I could have prevented that, and now I need to deal with explaining to the grieving parents why I made the choice I did and do I lose faith in "thou shall not kill," or do I stick to that belief in the face of the grief it is causing? Can I really be said to be a virtuous person? Or I kill him, BUT, he was some sort of cult leader and now his cult members are going around spreading terror in the streets, and I could have prevented that, and maybe there was some other way, and now I need to deal with all those poor people with the horrible burns and the orphaned children who have seen horrible things and do I lose faith in my convictions to kill those who deserve it, or do I stick to the belief, seeing the consequences of my actions on the haggard faces of the refugees from my town?
The aesthetic this trucks in isn't interested so much in my decision to kill him or not, but rather my decision to keep my convictions or not in the face of the disaster they're causing. The conflict isn't about my initial choice, it's about living with the consequences of that choice, choosing it again day after day. The question isn't "Which of these two lovely women do I marry?" but rather "Now that I am married, and we are fighting, do I stay that way? Why or why not? What is the cost of that?" (Wasn't it Kirkegaard who said something along the lines of "If you get married, you will regret it. If you don't get married, you will regret it."?) "Shades of grey" means that, murder or not, I can never really make the claim to being the Good Guy -- I made bad things happen. Maybe it was worth it?
PS isn't quite so brutal but the aesthetic is similar. That is, the interesting bit isn't to choose between two things that are desirable but in conflict, the interesting bit is in the personal struggle to live according to one's convictions, and exploring the conflicts that happen as a result of that. The choice isn't "Am I a Signer or a Sensate?", at least after character creation, it's "Can I continue to be a Signer in a world that makes that choice difficult?" Can I live with the consequences of my actions? Can I accept what negative things my belief means? Can I persuade people that they're worth believing over the competition? It's not the decision you make once, but the decisions you make every day, in your own heart.