While the meat of the answer is perhaps disappointingly dull--pure irrational, rosy-tinted nostalgia—I do have some rather elaborate post-facto rationalizations for why I still use it in the campaign.
But first let's back up and talk about the short, cut-down-in-the glory-of-its-prime history of this alignment scheme. Rearing its head in the blue book of the late 1970s, five-fold alignment as per the book (Holmes, Basic D&D page 8) is a gloriously opaque and mystifying cosmic arrangement. Good and Evil were readily grokable: the eternal “us” and “them” of the American mind, Law and Chaos to one unfamiliar at the time with Poul Anderson and Michael Moorcock slightly less (but the names evoked great ideas), their axial interaction even more unclear.
That it was all illustrated with a graph that placed unfamiliar monster types made it seem all the more inexplicable (“ok so, teleporting dogs equal the good kind of law and dragons made of brass are chaotic and good, got it”). Its vagueness left me filling the void with strange and open-ended whimsy in what it all meant.
Of course time spent around the endless (yet enjoyable) exegesis of the OSR has rudely disabused me of my naivete. It's fairly clear from remarks in Dragon #52 that the good doctor never intended to have this alignment scheme at all, preferring instead the traditional three-points of OD&D. The new scheme was presumably added as a bridge to AD&D which was being introduced piecemeal at the time.
The other piece that I find interesting is that five-fold alignment appears to not have just been a truncated and simplified presentation of the nine-point, pain-in-the-ass alignment that all right-minded people loathe and despise, but likely the “first draft” of what alignment was supposed to be in AD&D circa 1976. Evidence for this can be found in Gary Gygax's article in Strategic Review (Vol 2, #1) where he presents the expansion beyond the Law-Chaos arrangement.
This article is fascinating because it presents a number of interesting concepts, mostly dropped or radically changed as the game developed. The most immediately noticeable is the concept of alignment not as a static either/or but as a great spectrum of thought and behavior. Races and individuals are all being pushed and pulled along the two radials outward toward the cosmic realms (you can see here with borderline places like Nirvana and Limbo best the beginnings of nine-fold and the outer plane cosmology of later years).
|Scan from Strategic Review (Vol 2, #1)|
Your alignment is purely a matter of which of the four quadrants you rest in your vector at a particular time. In fact over time this can even mean that a “player-character who continually follows any alignment (save neutrality) to the absolute letter of its definition must eventually move off the chart...and into another plane of existence as indicated.” One can thus be more chaotic or more evil than even another in the same alignment and that you can evolve into a divine/infernal being if you go so far. Wild.
There are a few more fascinating quirks laid out here about the implied cosmology of D&D worlds at that time. Law seems to be an artifact of human civilization for instance, “Humanity most of humanity falls into the lawful category, and most of lawful humanity lies near the line between good and evil. With proper leadership the majority will be prone towards lawful/good. Few humans are chaotic, and very few are chaotic and evil.”
Strangely (and I am still parsing this out mentally) humanity's “mythical and mythos” gods are creatures of chaos the “benign ones will tend towards the chaotic/good, and chaotic/evil will typify those gods which were inimical towards humanity.”
Couple that with the inclusion of Heaven and Saints as the embodiment of Lawful Good and Hell and the Devils as that of Lawful Evil and you have a weirdly bifurcated cosmology between a Christian-like lawful (though dually opposed) overworld and a “everything else” chaotic overworld.
|Scan from Strategic Review (Vol 2, #1)|
That clerics all must either “remain completely good or totally evil, although lateral movement might be allowed...with or without divine retribution” boggles my mind especially since Gygax states explicitly that the gulf between good and evil is greater than that between law and chaos. Does it imply that the (perhaps solitary) LG “God” tolerates the “pagan” CG gods (and vice versa) in their mutual struggle against the LE “Devil” and the host of demonic gods of CE? Is it a great cosmic kitchen sink battle like the Lord of Hosts teams up with Thor to whip on Old Scratch and Cthulhu? Or what?
Neutral is a glorious muddle (naturally called “self-explanatory by Gygax). My read is that it's not all about the cosmic balance (a very lawful, orderly concept in my opinion) of later years but more of a gray-shaded place of “moral” ambivalence (with a relative tendency toward one of the poles). Druids, the only human clergy acknowledged to inhabit this spot, have a wonderfully non-granola write-up here: “Druids serve only themselves and nature, they occasionally make human sacrifice [my emphasis], but on the other hand they aid the folk in agriculture and animal husbandry. Druids are, therefore, neutral—although slightly predisposed towards evil actions.”
How does that relate to the Hill Cantons campaign?
Well in keeping with my pretensions and distaste for alignment to be anything but a vague backdrop in actual play, five-fold alignment appears as humanity's limited, warped, half-right theoretical view (or ontology if you want to get really high-falutin') of how the HC cosmos works. That cosmos is dominated by the tension between the deadly-dull, seemingly-stable, and entirely-human Corelands and the dream logic of the Weird (full bullshit exposition here).
The power of the Corelands somewhat maps toward the lawful, though Lawful Good is mostly an aspirational ideal of the monotheistic followers of the Sun Lord with the lion share of the conniving, self-serving actual mass of humanity solidly “neutral” (or at best borderline, softly lawful evil or good) especially in the borderlands. And while much of the otherworldliness of the Weird maps to the Chaos side of the chart—and much that is inimical there to the Chaotic and Evil—not all of it is there. Because it represents dream logic—perhaps it even being a feverish projection of the human mind—there are also authoritarian distortions like the Eld who can only be described as Lawful Evil.
Confused yet? Well good, because that's the take-home message. Why I enjoy and appreciate five-fold alignment is that was poorly-explained, briefly-used concept that existed between the simplicity of three fold and the overly-explained, too much-tied in with the later orthodoxy of the Outer Planes whoha of nine-fold alignment (and thanks Dennis for articulating this). And it's in that sweet, ambivalent, underwritten spot between classical elegance and baroque excess that I enjoy filling in the blank spots with my own over-wrought silliness.