With this chapter we see the introduction to D&D of the nine-point alignment system. In OD&D, there were simply three alignment: Law, Neutrality, and Chaos. Gary altered this in The Strategic Review #6, adding Good and Evil to the mix to give five possible alignments: Lawful Good, Chaotic Good, Neutral, Lawful Evil and Chaotic Evil. This system was carried into the first D&D Basic Set.
In AD&D there are nine alignments, with the addition of Neutral Good, Neutral Evil, Lawful Neutral and Chaotic Neutral. It's not made clear what purpose alignment serves in the game, but the nine alignments are each given a brief description. This is more than can be said of previous editions, where the space given to each alignment was perfunctory at best.
Let's take a look at each alignment in turn:
Chaotic Evil: Values freedom, randomness and woe. (Really? Who values woe?) Disdains law, order, kindness, and places no value on life. Seeks power in a system ruled by caprice and their own whims.
Chaotic Good: Values freedom, the welfare of others, and individuality. Specific mention is made here of characters "promoting the gods of chaotic good", as though that's what they're expected to do. Later on Gary states that the descriptions are generalisations, and this is one that I'm glad to lump in that category.
Chaotic Neutral: Places randomness and disorder above good and evil. Again, the way this is described make the character sound like a crusader for a cause.
Lawful Evil: Respects law and order, but place little value on life, beauty, truth, and freedom. Seeks to use discipline to impose their yoke on the world.
Lawful Good: Strictly upholds law and order for the common good. Believes that certain freedoms must be sacrificed to bring order. Values truth the most, and also life and beauty.
Lawful Neutral: Views regulation as all-important. Believes universal harmony depends on law and order.
Neutral Evil: Dedicated to - and I quote - "maximum evilness".
Neutral Good: Believes in a balance between regulation and freedom to bring about beneficial conditions for all. Curiously, it's said that they value intelligent creatures more than unintelligent ones.
True Neutral: Views all alignments as part of a natural system, and believes that this balance should not be upset by unnatural forces, including the interference of intelligent creatures.
So, looking at the above, just what is alignment? Simply going by the name, it should be the side you are aligned with. This implies that Good, Evil, Law and Chaos are fundamental forces of the universe, and at war with each other. This is backed up by the descriptions, as several of them describe characters advancing the agenda of their particular alignment.
It's also clear, however, that alignment describes a character's morality, ethics and general behaviour. Lawful good characters act a certain way, chaotic goods act in a different way, and chaotic evils act even more differently still. The behaviours given here are said to be generalisations, and yet those generalisations must come from somewhere. For the most part NPCs will behave much as their alignment dictates, as described here in the PHB. There will be outliers, and PCs are likely to be among them, but they are just that: outliers.
So alignment in AD&D is both your behaviour, and the side of the cosmic conflict you fall on. This raises a question, though: does behaviour dictate alignment, or is it the other way around? I would be inclined to go with the former. No creature (except for certain magical types, like demons and such) is born evil, good, chaotic or lawful. (I would say that any infant is by this logic neutral, which cuts the whole "paladins killing orc babies" dilemma off at the knees right there.) They will, however, be greatly influenced by their cultural upbringing (and genetics as well, I suppose), and if you're a baby orc surrounded by chaotic evil relatives, it's a good chance you'll grow up to be chaotic evil as well. The chance for good is there, of course, but it's a slim one.
So the way a character behaves and thinks determines the side of the conflict they're on, and this may have a more profound effect on their inner selves than you would think. After all, there are magical effects that work based on the target's alignment. It's a palpable thing that can be detected. There are even languages intrinsic to each alignment, and the inability to speak languages of differing alignments. Whatever your alignment is, it connects you to something greater than yourself. I wonder if this could perhaps be tied to the article Gary wrote in The Dragon #8, where he posits the idea that certain creatures are connected to the Outer Planes, and that each creature type has its own sub-plane. Mostly this idea was put forth as a way of explaining the immunities of various creatures, but it could work to explain alignment as well. It seems probable to me that every being has an intrinsic connection the the plane most connected with their alignment as well, forged in the developmental stages of their upbringing.
The question must also be asked: are all characters crusaders for their particular alignment? Of course the answer is no. Most characters will serve their cause unknowingly, furthering it through their own actions and goals in spite of their ignorance. Paladins and clerics are different, as are druids, and there will certainly be others who serve their cause knowingly. But I feel like most people in the standard D&D world go about their business with little thought for Good, Evil, Law and Chaos.
Changing Alignment: It's said that involuntary change is possible, but voluntary change is very difficult. If the ideas I've brought up above are at all true, this makes perfect sense. I seems as though True Neutral characters have an easier time of changing alignment than anyone else, and this also makes sense: by their nature, they would have no connection to any of the Outer Planes.
Gary says that "evil alignment can be varied along the like axis", and I'm not entirely sure what this means. Later on "axial change within evil or good" is implied to be easier than other kinds of change, and I wonder about this. Does this mean that it's easier to alter alignment between good and evil? Or easier to change between law and chaos? Am I stupid, or is this poorly worded? (A glance at the DMG tells me that this will all be cleared up in time, though perhaps said clearing up has little to do with the way things are worded here.)
Regardless, voluntarily changing alignment requires sacrifices, appropriate acts, and possibly a quest. It's also next-to-impossible to change back to an alignment you have already forsaken (presumably said forces will be reluctant to take the character back into their good graces).