Sci-Fantasy

Looking for cool reasons for magic to work in a post-post apocalyptic sci-fi setting that aren't:
> Nanobots
and/or
> Special Radiation

What about
> Magic

Not satisfied?
"Throughout history there have been tales of witches, shamans and strange phenomena. During the industrial revolution, many of these cases of 'magic' were considered false, given that there was no scientific basis for them. Of course, we now know they were just blind-sighted because they did not have the right measuring equipment yet...
Here at Arcano Co we've put years of research into the field of magic together to bring you a brand new product! Magic-in-a-cup! All the occult powers you can handle with the delicious flavor of pumpkin spice! "

You could go with the somewhat abandoned "next stage of human evolution" thing that used to be really popular.

Alternatively, whatever weapons did the apocalypse were so powerful they broke a hole into a parallel dimension where the rules of reality are different, and it kinda bleeds over.

This. The world ended, weird things are going on, nobody cares about if it's nanobots or witches or the Eighth Ray they just care about surviving it.

I did consider "new understandings," but it easily teeters on "sufficiently advanced technology," and while I'm very much trying to explain it with sufficiently advanced technology, I don't want the, and I use the term loosely, explanation to begin and end with, "sufficiently advanced technology."

also, just to clarify to prevent future misunderstandings, by post-post I mean the world ended several generations ago, and man is well under way in putting humpty dumpty back together again. Think Dedd's cursed earth, with man living in sparse, densely packed cities, with a disparate speckling of settlements between them, if it weren't intentionally designed and written to be as persistently dystonian as possible.

In that case you can use more than one explanation. There's a scientific revolution going on, one tribe's scientists are all in on the nanobots theory, another tribe has experiments it claims proves the small-group-of-immortal-psychics-in-vats theory, and the loner in the desert will let you see his notes on his theory of the calamity putting a hole in the topography of space-time, if you sweet-talk him and bring him gifts. Ask the old folks in the village and they'll tell you it's hoodoo and make the warding sign, and even as cosmopolitan as you are there's a part of you that can't help but think they're right.

Psionics

Though I am partial to ubiquitous nanobots

Quantum parallel universe magic.
It puts a logical limit on what effects can be acheived: you can only alter the target's past and probability. Even with infinite universes, impossible things never happen.
For example, you can't raise an actual undead zombie that doesn't need water or oxygen because that goes against so many facts of biochemistry in our universe, even if somehow the source universe made it work.

>if you sweet-talk him and bring him gifts
You made me imagine a post apocalyptic Harvest Moon and now I'm sad.

Just do what Bungie did with Destiny and it's
>magic, i aint gotta explain shit

Because it's fucking magic, so why are you explaining anything?

Magic just works. Well, there's a sort of science behind it's study, but thaumaturgists aren't much closer to discovering how the hell it's inner functions work than they were in the middle ages. The whole apocalypse thing didn't exactly help matters either.
The practical side of things is fairly well charted though. Infernal grimoires list literal millions of potential thralls and patrons to summon or bind.

In fact, trying to actively memorise enough soul names, glyphs, sigils and ratios of blood to salt for evena small selection of minor magical rituals is nothing short of lunacy. And that's not even getting into the fact that arcane knowledge twists the mind.
So mages use digital storage for both grimoires and to store spells in 'scroll' form. All the hologram windows and sigils floating aroudn them are in fact aids to memory and the mage effectively Googling "how summon Ath'krodan in Arcanum4++"
The very best mages can cast off the grid. They burned a spell or two into their mind, maybe even their soul. No aids, no spell.txt, pure memory and will.

Allthough even digital storage needs periodic wipes and restorations to prevent Weird Shit happening. Finding an old mage Lexicon is equally terrifying and valuable. It can have encoded spells and insight into the maddening world of magic.. and it can also have Bad Stuff.

>magic
Because magic, that's why.

I really wish Destiny's game was as fun as its setting.

That said, if you tell your players to ignore anything that happened in the in-game campaign (you as GM can always recycle cool assets after all) it makes a pretty fun tabletop.

Magic already existed, it was just incredibly weak and subtle. At least, until some clever and amoral as fuck wizards decided to perform a global thaumaturgy ritual, maneuvering the world into nuclear war and then using the billions of lives killed by atomic fire as burnt offerings.

Make it a natural development of humanity's capabilities without ever mentioning magic or psychic powers

That's how Dune's whole setting worked

Try Destiny lore. Half of it is straight up magic, but that magic runs on pretty sweet technobabble.

Like wizard's robes weaved from hadronic essences drawn forth from quark splitters. Or a miniaturized black hole frozen on the event horizen.

Or Sword Logic. Just...Sword Logic.

Magic is powered by the souls of the dead. There are a shit load of dead people now.

So the Rifts approach?

I thought RIFTS was all leyline bullshit.

It is, but the Leylines were activated by the massive casualties from a nuclear war. They had basically dried up, but all the spirits passing through them at once reinvigorated them.

Cowboy bebop and Outlaw star did chinese Geomancy

Next-level information technology.

"I can't explain to you how it works. I'm not trying to be aggravating, but your language simply doesn't have the words for it yet. I'm not sure you even have the conceptual foundation for it. You still believe that all of your machines have to be physical in nature to perform their functions."

I like this

Just take the ideas that Destiny presents; There are fundamental forces in the universe that exist in all living beings and cultivating it (the light) or communing and joining with it (the darkness) gives you the ability to become Para-casual which allows you to reshape reality a bit.

Doing shit like throwing a fireball is small fry compared to creating your own afterlife and literally cutting a hole in space to go between but compared to how DnD does magic it's all fairly tame really.

Damnit.
Filled the post limit with my thoughts, then it all got deleted.
I'll be back.

For now,
OP, magic races yes or no?
What scale of magic are you looking for? Full D&D?

My thoughts pointed out the pros and cons of ideas already presented.
My idea involved "magic teaching demons" from another dimension like said.

Um no. It's the PPE (Potential Psychic Energy) release at death automatically doubles at time of death. The simultaneous death of millions caused the leylines to surge which opened Rifts to other dimensions. This started a chain reaction with tsunamis, flooding, earth quakes. Atlantis warps in and floods the seaboard. Millions more die and the leylibe surge more.

I'm thinking of using something like it, but taking Numenera and making it more techy using different options in the Cypher System.

Close enough.

Sufficiently-advanced technology that still works even though nobody understands how, so it's effectively magic.

Boom, done.