Basic Information
Sometimes the choice is clear: There is a good side, and there is an evil side, and it is easy to distinguish which is which. Not with this trope. In a grey versus grey conflict, neither side is completely good or completely evil. Both sides have a strong justifiable reason to be fighting. Both sides have their share of upstanding, admirable individuals and vicious, slimy scumballs. Where this extends into a metaphysical level, dualism is the likely result.
How such a conflict ends depends on whether the tone is idealistic or cynical If it is idealistic then both sides eventually realize their fighting is futile and make peace. If it is in the center then one side crushes the other, and this brings peace - a hollow depressing peace given that a faction with noble ideals has died, but a peace nonetheless. If the tone is cynical, then the sides become more and more evil as the fight wears one until the more vicious, bloodthirsty one finishes the other(s) and ushers in a new era of darkness.
All of this ignores the possibility that they might ally against an unambiguously evil third faction, after the defeat of which they either make peace with each other or at least decide on a truce.
This also assumes ideological conflict - for worldbuilders who want a less fantastical tone, and to create a setting in which most conflict is, as in the real world, about resources, then grey and gray morality is likely to be the way forward. Country A and B may well be morally interchangeable and merely in dispute over some productive farmland or control of a warm-water port, in which case the morality is likely to be pretty grey all around. Likewise in settings where the enemy is not monolithically evil and your allies not all good - these sort of things add depth and congruence to a world (but may not suit all playing styles).
Even where the fantastical is involved, many real world mythiea are distinctly hazy on matters of good and evil - the Romans and Greeks lived with the idea of gods who often struggled to embody more than one virtue and, whilst prone to punish those who annoyed them, were not exactly definers (or practitioners) of goodness or morality. Where a "good" act is defined by "that which experience shows the gods approve of" rather than any moral reasoning then things become a lot greyer (especially if the gods are inconsistent).
See Also
- Black and White Morality: Clear good and evil, one of the most common forms of dualism.
- Blue and Orange Morality: At least one side is clearly alien. Usually involves otherness tropes
- Black and Black Morality: Evil versus evil. Risks darkness-induced audience apathy.
- White and White Morality: Good versus good. Risks turning into a sugar bowl.
- A Lighter Shade of Grey: At least in name grey and gray, but overlaps with protagonist-centered morality.
Sources
http://tvtropes.org/pmwiki/pmwiki.php/Main/GreyAndGrayMorality
Game and Story Use
- Some players prefer a black & while morality where they know it's always okay to kill the orcs because that's what they're there for. Others enjoy a little ethical ambiguity. It keeps them on their toes and makes them have to think a bit.
- This arcanist's wife always seems to be romantically attracted to the evil megalomaniacs. But then that's a completely different trope.
- Some users may find that the lack of objective morality adds to the heroism of someone actively choosing to do good - if good and evil are clearly defined and people can be easily sorted between them (as in most heroic fantasy) then morality is simply a matter of partisanship - if it requires real effort to determine, chose and follow that which is good, then so much the greater the heroism. Values dissonance of course, applies in all cases.
- This trope lends itself well to the sort of (actually fairly realistic) setting where every apple has a worm in it - your post apocalyptic society might be faced with the choice between an oppressive faction that will actually restore a modicum of civilization and one that will leave people their freedom at the cost of poverty and danger. Alternatively, perhaps the PCs need help against some kind of monster menace … but because the menace is still behind the wainscot the only people prepared to help are, essentially, the fantasy expy of the Klan.
- Actually, that could work pretty well for a 1920s CoC scenario - need to root out a nest of Dark Mother Cultists or Deep One hybrids? Perhaps the only people prepared to help are your friendly neighbourhood racists … after all, an organisation that far down on Romanists and black people is going to have no time at all for goat-demon worshipers or fish people.
- Failing that, the mafia might be of some use … and they're not exactly model citizens either.