The concept of symmetry in philosophy is primarily an eastern derived one
I think this is a little simplistic. For instance, Manichaeism and other dualistic religions contain ideas along these lines.
And to quote Bertrand Russell on Kant (History of Western Philosophy, p 679):
Like everybody else at that time, he wrote a treatise on the sublime and the beautiful. Night is sublime, day is beautiful; the sea is sublime, the land is beautiful; man is sublime, woman is beautiful; and so on.
We could even point to the fact that (at least as it is written) "To everything there is a season . . ."
Buddhism meanwhile basically says evil is the world's default, not good. Life is suffering and all pleasure is basically the (temporary) absence of suffering, rather than an independent experience. The goal of life then is to reduce suffering (but not to eliminate it) by recognizing the impermanence of all things, detaching oneself from the material world, and denying the ego which is (in Buddhist philosophy) an illusory concept with no bearing on the fundamental metaphysics of reality. The core ethos of Buddhist is actually kind of annihilationist in nature
Like most religions and other lived traditions, Buddhism has many schools and variants.
But I think it is pretty mainstream to uphold the doctrine that an enlightened person dwells in the "four divine abodes": equanimity, compassion, loving kindness and sympathetic joy. That is not a doctrine of mere annihilationism.
This is also brought out in the
Lesser Discourse on the Stems of Anguish. The Jains say to the Buddha, "Friend Gotama, pleasure is not to be gained through pleasure; pleasure is to be gained through pain. For were pleasure to be gained through pleasure, then King Seniya Bimbisāra of Magadha would gain pleasure, since he abides in greater pleasure than the venerable Gotama." The Buddha replies that, unlike the king, he is able to abide, without moving a muscle, for days and nights of meditation, experiencing pleasure - whereas the implication is that the king's pleasure is more fleeting and unstable, depending upon the presence or absence of external, worldly things.
There are interesting discussions to be had - probably not on these boards - about the psychological plausibility of the Buddha's claim about meditation and pleasure. But it seems clear to me that he is insisting that a person who is enlightened (in the Buddhist sense) and therefore steps off the wheel of suffering is not stepping off the wheel into annihilation, but is stepping off the wheel into a state of pleasure. I'm sure there is a reading of this consistent with [MENTION=16760]The Shadow[/MENTION]'s claim that evil (in this case, suffering) is a privation of good (in this case, pleasure) rather than self-subsistent.
Evil is not merely the absence of good, nor it it less real than good. If it were, it couldn't hurt us... it'd be illusionary.
its impossible to make "good/evil for its own sake" something unless their is an objective Good or Evil.
There are limitations on this board, and this thread, as a forum for discussing the metaphysics of morals. But at the risk of being simplistic, neither of these claims is easily defended.
For the first: "evil" is most naturally regarded as a property of things. Whether that property is a self-subsisting one, or whether it is simply an absence (of good) is something that was very important to the scholastics (given their theories of substance and attributes) but is one that I am happy to sidestep. But whatever the nature of evil as a property, it is not evil that harms people. It is individual acts, involving individual objects, that cause harm. Evil is a property of (some of) those things. (Some harm is caused by innocent acts and innocent things. Some may even be caused by good acts and good things.) It may even be that the very same thing that makes those things harmful makes them evil (eg many people, I think, regard nuclear weapons as evil because of their tremendous capacity to cause harm; many people regard the consequences an action has as an important determiner of whether or not it is evil).
But it is not evil, itself, which causes harm in these cases. "Evil", like other properties, is an abstract object; and one of the principal characteristics of any abstract object is its inability to participate in causal relations.
For the second: Simon Blackburn is probably the best known contemporary defender, in English-language philosophy, of anti-objectivism about morality and other values. But he would regard it as perfectly feasible for someone to pursue good for its own sake. That simply means that the person is motivated to pursue certain ends and actions, which have the property of being good, precisely because they are good; just as someone might collect Picasso sketches for their own sake, collecting them precisely because they have the property of having been drawn by Picasso and regardless of any other property (such as eg whether they are aesthetically pleasing).
The fact that the property of being good is not an objective property doesn't make pursuing good things because they are good any less feasible.
Here is my best argument for the canonical status of Planescape and the reason references to the Blood War and such in the Fiend entries in the monster manual would not be unwarranted.
<snip history of various D&D texts>
The fact that some people don't like some of the additions, such as the Blood War and Yugoloths being master schemers, no more makes it uncanonical than a person disliking Vader being Luke's father makes "The Empire Strikes Back" uncanonical.
Many people who play D&D don't regard it primarily as a story - a collection of canonical background events, history, etc. They regard it as a (loose) collection of tropes whose expression occurs via a mixture of flavour text and game mechanics.
For those people, the fact that some authors of those tropes also went on to write stories using those tropes, and attaching them to more detailed background events, history, etc, is not relevant to what they conceive of as D&D, nor what they are looking for from it.
Of course, this is a matter of degree, because every bit of flavour text has a tendency to import some background: eg the existence of ice devils suggests the existence of a lower plane that is icy; elves having a +1 to hit with bows suggests that bows exist in the world; etc. Plus there are the named spells that have been part of the game for a long time.
But it seems to me to be quite reasonable for someone to be happy with ice devils - a feature of the game present in multiple core Monster Manuals over the game's various editions - but not want the core material of the game to include every element of ice devil elaboration ever presented by some TSR or WotC author in some supplementary volume. That sort of stuff can safely be left for later products intended for enthusiasts.