Conformity and following tradition are Lawful behaviors, while rebellion and defying tradition are Chaotic. So you'd think that a viking from a raiding society, where burning and pillaging their way across the land is both traditional and what everyone else is doing, should be as Lawful as they come. The internal motivation looks pretty much the same as for any other group of humans. Unlike the portrayal in fiction, real people from real raiding or martial cultures follow their taboos and honor their ancestors and like to wear nice clothing and have sophisticated legal systems; they don't feel like they're being chaotic and evil, they feel like they're being lawful and good.

CE that's an alignment handed to them from the outside. 

There are people who feel themselves chaotic - bandits, pirates, counterculture - who stick out from the society they were raised in, but most people are lawful with a different set of laws.

(The pope wouldn't advance this argument in those words because he's aware that it isn't quite true in-universe - Golarion cultures build identities around being culturally Lawful or Chaotic, because of course they do, but there's a modified and caveated version of the argument which he could and would make.)

(Noted.)

Alignment isn't about how you feel, it's about what you do.

And what they're doing is being upstanding citizens and honoring their ancestor's customs! Just in a different culture! Lawful characters are supposed to be all, "my word is my bond" and "I must defend my family's honor" and I'd be surprised if there's any negative correlation there where people from raiding cultures are more likely to lie or less likely to defend their family's honor.

(This isn't true either; cultures where it's normal to do things which are Judged as Chaotic are statistically more likely to laud other behaviors which Pharasma Judges as Chaotic, because that gives them a coherent cultural identity as a Chaotic culture. There's a softer version of the claim which the Pope could make, though.)

(Ah, he'd make the softer version of the claim, then. And go as far beyond it as to say that these Golarion cultures are culturally "chaotic" out of an excess of the species-typical "lawful" cowardice and conformity that so often crushes down the human conscience and the nobler parts of the human spirit just as readily as it inhibits human malice.)

(Most of your audience thinks that this is an extremely weird claim to make, but there's actually more than one Korvosan in a place to suddenly realized that if they'd have been Chaotic in a different culture for the same reasons that they are Lawful in this one, it reflects poorly on them. Where they go from this point varies: one converts to Irorism. This man will go on to apprentice under a monk and, one frabjous day, venture into the tulgey First World to fistfight a Chaotic jabberwock. But that's a different story.) 

Okay, Kroft will provisionally accept that that's the case. She expects that following tradition and keeping one's word and defending their family honor all contribute positively to their alignment.

But clearly whatever benefit they're getting is swamped by other Chaotic things that they're doing; it's an objective fact that most Korvosans are Lawful and most Shoanti are Chaotic - there are spells to just check.

But we wizards are lucky our predecessors in the art produce so much writing in the course of their own research... even if they drive us half-mad making sense of their watery spell-diagrams and arid correspondence. Else nearly all a wizard learns in his life would die with him, instead of merely most of it. 

If you planned to stay a while on this side of the curtain and I might offer to lend you my own notes - and my late grandfather's - and my advice on making sense of them.

But, alas, while I intend to live until it kills me, there's little point schooling a cooling cadavar.

...Print is a potent palliative and perhaps I could be convinced to languish longer. 

I think that Law is about organization.

Lawfuls are personally organized, and organize themselves into orderly factions, whereas if a Chaotic isn't straight-up drapetomanic, he's certain to be a diagnosable oppositional-defiant or she a hysteric. 

...

Every Chaotic believes in their heart that they're more important than anyone else. That's why only Lawful alignments scale. 

I don't think that's true.

You don't?

Mull has magic and is dressed like a pauper. I don't know whether, before I hired him, he healed for free, or whether he charged money and gave it away, but either way it doesn't seem like selfishness is his vice.

Well, let's distinguish selfishness from self-importance, since it's the latter which I understand to be the complaint. I don't think I'm unreasonably and uncooperatively self-aggrandizing, but I can easily see why someone might reasonably think so. 

I take your correction, although I don't think that Chaotics are much more self-aggrandizing than Lawfuls on average, and at any rate it isn't self-aggrandizement that limits scale; Infernal Cheliax doesn't run on humility!

Scale isn't necessary for organization, but organiztion is necessary for scale - the 'u' to scale's 'q.'

The more members your organization has, the more members it needs to coordinate. In a naïve model, every new employee needs to coordinate with every other employee, so adding a new employee costs (n-1)*c where n is the number of employees and c is the average time (i.e. labor cost) of coordinating with a fellow employee. If your organization's average time spent communicating with a fellow employee is a half hour per week, then you can't actually have more than 80 employees and retain a 40hr work week, because you run out of time in the week to talk to anybody else.

So organizations must organize -- hear that term both in the colloquial sense of imposing order, but in the deeper, more literal sense of "organ-ize". They arrange themselves into organs -- functional subsystems of the larger system, which can behave more autonomously of one another.[1]

Large organizations are necessarily Lawful, but Chaotic individuals can and regularly do join Lawful armies - in fact, they're often encouraged or coerced to by their family in the hope that the army will make them Lawful! And of course Lawful individuals regularly can and do join Chaotic "armies," which, symmetrically, make them Chaotic! Since organization is necessary for scale, and organization is a component of Law, saying that Chaos doesn't scale is the same as saying that Chaos isn't Law. You don't have to reach for other supposed defects of character that Chaotics possess. 

-

1. This entire section is taken from this blogpost (very lightly edited to change the emphasis): https://siderea.dreamwidth.org/1177349.html

Delmore, the orchestra, undirected, plays discord and cacaphony. Raise your wand and conduct it with me. 

...This is a terrible idea. But. For 80,000 gp, as much of your tutelage as you see yourself as already having offered, and your word that if I'm killed or petrified or soul-trapped or bodily transported into the Abyss while in your service you'll see me raised or freed, I will follow you until I make seventh-circle and you make ninth, or until you die in a way I can't fix, or until the world is saved, or until you give up on trying to save it, or until I pay an 80,000 gp penalty for breaking this verbal contract.

Pricey.

I know you've been saving money to construct your phylactery, you can't need another 80,000 just for that.

If there's any chance I find myself running the Gantelope with you, sir, I should like to have spent my WBL in advance of the trial.

Then on the condition that your ascension as a lich does nothing to disadvantage Golarion's mortal civilizations in their contest for freedom and survival against the shadows, Blood Lords, Whispering Way, forces of Hell, and other adversaries as they present themselves, for as long as a free mortal civilization persists on Golarion, you have a deal.

A "lawful" character keeps their word. Abadar is "lawful" because he always tells the truth. Abadar's truthfulness lets people build on top of each other's promises, which keeps them from working at cross purposes and lets them accomplish things that they couldn't alone. "Law" is about organization, and truth is Abadar's organizing principle. 

Geryon does not keep his word. Geryon lies, constantly, about everything. Geryon's deceits let him trick people into acting against their interests. "Law" is about organization, and lies are his organizing principle. Geryon counts as "lawful," according to Pharasma, which tells us that while truth can be "lawful," it isn't necessary for "law." 

Irori is an ascetic who believes in accomplishing everything with his own power. Irori is Lawful, according to Pharasma. Which tells us that having an organizing principle can be "lawful," but isn't necessary for law. isn't necessary for Law. So it turns out that "law" isn't actually about organization.

What's Law, then? You can lie, "lawfully," you can reject civilization, "lawfully," you can break oaths, "lawfully." And "chaos" is the same way; you can be a "chaotic" muckraker who'd sooner die than bend the truth, you can be a "chaotic" trickster who uses deceit and the trappings of authority to Bavarian Fire Drill your way through life, you can be a "chaotic" mountain man who rejects civilization and lives by his own strength.

The better half of D&D Alignment is just your attitude towards the things you were going to do anyway, half of the other half is your Conscientiousness according to the Big 5, and the rest is just the general impression you give off. "Law" and "chaos" are meaningless as categories and should be relegated to the dustbin of history.