What constitutes...?

Good requires a capacity for mercy. Implied in this is a capacity for forgiveness. A character of good should avoid being a vessel for destruction or harm and should recognize that killing an evil being is not a good act in itself. It takes more than opposition to evil to be really good. A good character is not motivated out of hate, revenge, or greed. Good often entails personal sacrifice.

Evil lacks compunctions about hurting others. An evil character feels that his needs supercede others, and will harm others to obtain what he wants. He may use deception, violence, or manipulation to achieve his goals, but his methods are marked by self-interest, no concern for others' rights or dignity, no regard for dangerous consequences, and a willingness to cause suffering to others. An evil character may well be ruled by emotions such as anger, hate, desire, or those other bad things that Yoda taught us about.

I would also suggest that there be a definite idea that evil is much more accessible than good. If you behead a helpless prisoner out of a feeling of retribution for wrongs he has committed, you could still cling to your ideals of morality if you feel repentance for the act. However, if such behavior should become routine, you can probably expect to become evil pretty damn fast. It shouldn't take too much evil to slide that way, but to go back to good alignment, it should take more serious action. Either way, it's the change of heart that makes you want to do it, rather than the action itself, that causes the alignment shift.

Perhaps all of that is a certain bias toward good. As a society, we of course would rather have good than evil. I'm unsure of whether or not my idea that good is more demanding than evil is a reflection of my personal desire to glorify good and vilify evil. Perhaps more importantly, is it even possible not to glorify good and vilify evil? Can one recognize good from evil in an absolute sense and still manage not to prefer good?

Obviously, there should be some room for maneuvering. Alignment does not dictate or restrict what a character does, but merely reflects what a character does. At the same time, a character should have some room to act in mild violation of his alignment. A character who has a certain weakness for shiny gold coins isn't prohibited from maintaining a good alignment, but should generally answer to a higher calling.

So often one believes themselves to be doing "good" or acting virtuous but instead causes suffering. Whether or not someone feels a tinge of guilt (or doubt?) even when they belive themselves to be right, and whether or not that changes the absolutes of Good is a question better left for philosophers without clubs. An intresting discussion to be sure.

I think that's the very point though, good is nearly always preferable, espescially in the Cantian sense. The question goes, if everyone was doing this, would it make the world a better place for everyone, without harming anyone. Which is what makes it differint from True Neutrality in my opinion. Balance would ask what it "better" for the majority (or would this be law? Then again, when taken in its strictest sense, balance is a kind of law) while harming the least amount of people for maximum gain. Evil I guess wouldn't consider how many or how damaging its affects, simply that the act is done. I guess in this way one can justify evil by saying occasionally extreme measures are neccessary, the Road to Hell is afterall paved with good intentions.

But I digress from the topic. An often unvouched for ideal on the outer planes is that of Numonisis (s/p) or that which leaves a mortal (perhaps even paramortal, proxy, or power?) in awe, but without alienating them.
Perhaps an individual wandering across seas of endless Good finds the hearts impression of their own home, finds the idealized vision of their thoughts of home, and goes from it with a greater understanding of themselves and innate ideals of purity or virtue, forever changed by something within themselves. An ideal like this somewhere between dream and upper plane.

Matter, substance, which exists. Energy, motion, which acts. Time and space, defined by the meeting of the two. The dark antithesis which arises from the decay of all these three. And thought and perception, arising from all the prior gathered together.

Now thought might - might, by virtue of being the only one with a speaking voice - attempt to impose aspects of itself on the other forces. Matter becomes "Law", structure arising from the dance of atoms. Energy is seen as "Chaos", disorder inherent in the constant of motion. Time labeled as "Balance", regulating how its siblings interact. Entropy is called "Evil", destroying all semblance of shape or identity in the long run. And sometimes, forgetting humility or decrying zeal, Thought will even dub itself as "Good".

All a sham, of course. Maya, the illusion before all truth. The forces simply are, and need no labels of morality to govern what they do. Matter can bring chaos, energy order; time can corrupt and entropy bring new life. And the naming of things - with the chance to rename them yet again, in some other turn of the Wheel - can bring about the greatest balance of them all.