CyberSpyder said:
You miss the point. In reality, there are many different standards for judging evil, and most people don't agree on those standards. The people who hold the standards are aware that theirs is not the only standards, and even though they think their standard is 'correct,' they also know that it is possible to misjudge.
First, the notion that the puritans, muslims, ancient greeks, Hebrews, etc refrained from killing everyone they though evil because they knew that other people disagreed with their standards is absurd. They didn't and don't care whether people disagreed with their standards as they made and make perfectly clear through the various laws that punished public dissent. Under Sharia law, blasphemy against the prophet carries a death sentence. During the Reformation, heresy was sometimes punishable by death (although it was usually first punished by banishment). In some American colonies, heresy was punishable by banishment as well. Heck, even in "enlightened" modern Europe and Canada, challenging their standards for judging evil (by being "intolerant" etc) are punishable crimes.
Nor does the possibility of misjudging particularly bother them. They, of course, took, and take reasonable precautions to avoid convicting the innocent of those things (except in the case of Sharia law where only the word of a Muslim is acceptable as evidence and religious dissenters survive at the whim of their muslim neighbors), but the possibility that they could be misjudging what is heresy/sedition/etc never stopped them from punishing it any more than the possibility that they could be wrong about the identity of a murderer stopped them from hanging murderers.
No, RL societies that actually believe in good and evil and are confident in their standards don't kill everyone they judge to be evil for other reasons. It would cause more harm to society than it would prevent (as anyone who considers the implications of the notion that we ought to execute every thief, liar, embezzler, adulterer, wife beater, etc instinctively recognizes). And, more importantly, it would be unjust. Punishments must fit and not exceed crimes. (Something which has been recognized since the Code of Hammurabi mandated an eye for an eye and a tooth for a tooth and the Law of Moses forbid exceeding that mark). There are many kinds of evil which do not deserve death from human hands on earth.
In the D&D cosmology, however, there is a universal, objective standard for determining evil, that cannot be wrong short of magical interference.
Not necessarily so. That idea comes from the notion that there's some kind of "team evil" which acknowledges its evil nature without rationalizing it and opposes something they think of as "good." I don't think it's much of a stretch to suppose that followers of Lawful Evil gods might well think of Detect Chaos as "Detect Evil" and Detect Good as "Detect Weak-Minded Bleeding Heart follower of the slave morality". Detect Law for them would be "Detect Good." In any event, much like people IRL are ready to defend their friends and family as "good people" even though their actions their evil clearer than any spell ever could, a D&D world would be full of people who would rationalize and excuse the evil alignments of themselves, their friends, and their allies.
In any event, the notion that a D&D world that features neutral and evil gods has any kind of automatic, universal agreement on the nature of evil is naieve. When Olidamara Ralishaz and Zilchus have one code that espouses neutrality and Hextor advocates evil, "What's wrong with [evil]?" and "what's good about [good]?" become rational questions. (Those are questions that people ask all the time IRL; they just don't generally put it in quite such stark terms and usually preface them by denying that notions of good and evil have any normative meaning at all). When evil and neutrality have as much divine sanction as good, it's not clear that [good] would enjoy any special privilege in society.
Fortunately, it is also possible to tell when there is magical intereference, through 'detect magic.' A wise state would conduct periodic 'evil checks' through the city, and round up those who detected as evil. Those people would then be checked for magic, and divested of any magic on their belongings. If they then did not detect as evil, they would be freed. If they still detected as magical, either holding them in a cell for a few days or a couple of Dispel Magics would clear up that problem, allowing someone to determine their true alignment. They could then be dealt with appropriately - imprisonment and attempted rehabilitation in a kind state, or execution in a pragmatic state.
This, of itself, assumes a small and static proportion of evil in the state in question. If it assumes that those who are evil today will be evil tomorrow--which is not the case IRL or in D&D. It also assumes that only a small population of the state is evil. If even 25% (a very conservative number really) of the population has an evil alignment, such a plan would not be even remotely practical. (Which is one of the many reasons why RL socieities that were confident in their definitions of good and evil have almost universally refrained from annihilating the evil elements in their society).
It also assumes that it is just to jail/fine/execute people for their thoughts. If it isn't, then the mere act of beginning to execute your plan would swing its practitioners towards evil themselves. (And even if it weren't, the structures necessary for such an apparatus would themselves encourage evil in those designated to operate them. The power of such a system would be an invitation to abuse. One must imagine that many of the people who went into the various secret police organizations with good intentions were corrupted. And, of course, the concentration camp/death camp/reeducation camp/gulag guards and commandants would be tempted to evil too--if indeed they didn't have to be on the border of evil to want those positions).
This, of course, is going from the assumption that evil is defined by outlook. If it is defined by past actions, then the above would not be an effective way of preventing future suffering - the person plotting to blow up the city would not be caught, while the now-clean recovering drug addict who once did some terrible things would.
It also assumes that outlook is static. If outlook is not static, then the above is not an effective way to prevent future suffering either--even granting all of your assumptions. The person who delights in the suffering of others today could be convinced of the wrongness of that outlook tomorrow; the person who today is merely jaded and indifferent to the pain of people he doesn't like could tomorrow come to take pleasure in their suffering. And the person who today thinks she wants to help others could become bitter when people abuse her trust and then become vengeful or vindictive.
The person who was jailed or executed might not have gone on to do anything harmful while the others who were left alone could decide to do something wrong and harmful tomorrow anyway.
And, of course, it's also inaccurate to assume that all evil deeds are done by individuals with an evil outlook. There are lots of crimes of passion and crimes committed by people with impaired faculties (alcohol is a major factor in the commission of a lot of crimes) that are not necessarily done with premeditation or rational forethought and are sometimes regretted after the fact. The notion that you could prevent even the majority of crime through your program is naieve.
