I wasn't gonna join this discussion simply because neither Sergarr nor NullForce were making any points at all, let alone good ones.
But now that you've thrown that out there I can justify sharing my own thoughts.
The Chao/Law Good/Evil scale is meant to simplify an alignment in the Objective, not the subjective.
That Objective state can either be our world (usually is) or the world it's set in. In the second type you can have some very interesting ideas of chaotic, lawful and neutral, depending on the setting:
Pre English conquest, the gravest of all crimes in Welsh law was not murder, but theft. And while armed robbery was considered excusable under some circumstances, theft by stealth – theft absolute – could be a capital crime. Stealing from your own host, who'd taken you in and given you shelter… well. Very bad
However, most are due to OUR perceptions, OUR views of right and wrong. If we come across a race (AN ENTIRE RACE) which participates in slavery, mass murder, delights in killing and steals from others as much as they do eachother, we would perceive them as Chaotic Evil.
The entire race in DnD terms IS that, don't let the webcomic fool you. If someone decides to do a detraction from the trope and make a Drizzt Goblin, they can go ahead, but it's an exception from the rule- which is why it creates so much controversy.
In a similar fashion, the alignment restrictions of classes like Barbarian and Paladin are all in order to make the character abide by objective constants. A barbarian who removes his shoes to drink tea in the sitting room has ceased to be a barbarian as much as a Paladin who
burns the orphanage is no longer a paladin.
Therefore, it's up to the GM to figure out what counts as the objective morality of that game. Are all lesser races ok to kill? Is it bad to kill a woman or child, irregardless of the race? All that stuff is up to your GM, and sure you can judge him on it, but you'd better follow the rules.
If you had a character who was bound to their 'Internal Morality Scale', then either they'd never progress or grow as characters, or they'd be able to Sell any little horrible thing they do.
I was playing a Paladin at one point and there was a guy in our group who had been laid with a curse of compulsive gambling. His entire fortune was in jeapordy from this point on, so I bet him his entire fortune that he could go five minutes without making a bet, and then asked him to bet on snail racing or something silly- thus dooming him to give all of his money to me. He couldn't stop me, because the entire curse.
Point of the story here is, whilst I was doing it for His sake, the GM says 'As he goes to hand over his pouch, you get a massive foreboding feeling. This isn't Right'.
It wasn't. A paladin doesn't cheat or steal, even to protect or help.
Ethics is complicated. If you really wanted to make complex alignments, you should see if each character is Utilitarian (Most Good + Least Bad), Consequentialism (End justifies the Means) or Deontological (Doing bad things is bad, no matter what).