Dark Sun was official in two editions (2e and 4e); it was also referred to in 3e, but did not have official product.
Looking at the official releases in terms of the two campaign settings (2e, 4e):
2e: After references to pisonics, and psionicists as a class, in several places, the rulebook makes this explicit:
A Note About Psionics Dark Sun is a world of powerful psionics. Every player character has at least one psionic talent, as do many of the non-player characters and monsters. A thorough understanding of The Complete Psionics Handbook is required for full enjoyment of any DARK SUN™ campaign.
There are numerous alterations in the rules regarding psionics. You are required to have the additional handbook. NPCs have it as well. There are new and additional rules and proficiencies regarding psionics. It is baked into the lore of the game (such as psionic contests in arenas). There are additional spells to handle the fact that psionics are baked into the setting. There are multiple references to how common it is, and how (unlike magic) it does not degrade the environment.
Saying that, in 2e, psionics are not a part of the setting is like saying, "How about Gamma World, but no mutants." Sure. Why not. You can do anything you want, but it's not Dark Sun.
4e: Should I keep going? Under the Gods are Silent, it says, "In the absence of divine influence, other powers have come to prominence in the world. Psionic power is well known and widely practiced on Athas; even unintelligent desert monsters can have deadly psionic abilities." It has all sorts of rules for psionic power and "the Way." Also, it has a whole section about how psionics is prevalent on Athas, and how it used not just as a weapon, but even for commercial disputes.
Again, psionics is woven into the base setting assumptions of Athas and Dark Sun.
This is kind of a silly thing; you can say that whatever you want isn't "core" if you're pitching a concept ("How about Dark Sun, but in SPACE!!!!") but Dark Sun is completely interwoven with psionics as written and presented in official materials.
It is impossible to read the campaign setting and say to yourself, "Hey, you know what doesn't matter in Dark Sun? Psionics."
Looking at the official releases in terms of the two campaign settings (2e, 4e):
2e: After references to pisonics, and psionicists as a class, in several places, the rulebook makes this explicit:
A Note About Psionics Dark Sun is a world of powerful psionics. Every player character has at least one psionic talent, as do many of the non-player characters and monsters. A thorough understanding of The Complete Psionics Handbook is required for full enjoyment of any DARK SUN™ campaign.
There are numerous alterations in the rules regarding psionics. You are required to have the additional handbook. NPCs have it as well. There are new and additional rules and proficiencies regarding psionics. It is baked into the lore of the game (such as psionic contests in arenas). There are additional spells to handle the fact that psionics are baked into the setting. There are multiple references to how common it is, and how (unlike magic) it does not degrade the environment.
Saying that, in 2e, psionics are not a part of the setting is like saying, "How about Gamma World, but no mutants." Sure. Why not. You can do anything you want, but it's not Dark Sun.
4e: Should I keep going? Under the Gods are Silent, it says, "In the absence of divine influence, other powers have come to prominence in the world. Psionic power is well known and widely practiced on Athas; even unintelligent desert monsters can have deadly psionic abilities." It has all sorts of rules for psionic power and "the Way." Also, it has a whole section about how psionics is prevalent on Athas, and how it used not just as a weapon, but even for commercial disputes.
Again, psionics is woven into the base setting assumptions of Athas and Dark Sun.
This is kind of a silly thing; you can say that whatever you want isn't "core" if you're pitching a concept ("How about Dark Sun, but in SPACE!!!!") but Dark Sun is completely interwoven with psionics as written and presented in official materials.
It is impossible to read the campaign setting and say to yourself, "Hey, you know what doesn't matter in Dark Sun? Psionics."