My mind <i>reels</i> with the heady possibilities of this subject.
I <i>definitely</i> believe that magic in a modern game needs to be thought through. Of course, I think this about fantasy games. ;p
To get to the meat of it, and the nature of the things to be considered, what any GM who is doing this needs to ask themselves is: <I>What is the real nature of the universe?</i> This will be vitally important for both arcane and divine spellcasters.
Divine spellcasters don't need to worship particular gods. They can worship vague entities all they want and get spells for their troubles -- or, perhaps, even entities that do not exist!
To take some modern examples, what would happen if Roman Catholic preists, Muslim mullahs, Shiavite Hindu gurus and Native American shamans all got access to the same list of spells without any one of them being able to bring forth their god, or each of them being able to bring forth spiritual beings who *also disagree about matters of religion*. Well, I suspect what would happen is believers would be more certain and less tolerant, and all the theological arguments that go on, now, will go on at a higher level. Atheists, of course, would use the disagreement of spiritual forces to "prove" they were right, then spend their lives trying to do divine magic tricks with arcane magic to further their argument.
The whole matter would be different if the only people to get clerical spells were the followers of a specific religion, and if all the spiritual entities summoned by both divine and arcane spellcasters agreed about the nature of god. Oh, sure, some curmudgeons such as myself would say, "Well, that doesn't <I>really prove</i> there's a god!" -- but most people would eventually come into line . . . in time. It would be a tremendous social upheaval if, tomorrow, we learned that hitherto tribal god of some remote Polynesian people was the one, true god. Certainly some nations, religions and people would attempt to murder all the practicioners of this religion, which I imagine would be an exercise in futility in the long run -- after all, they are fighting both the truth and the will of god.
(Or worse, what if the people who get clerical spells do so by worshipping a group of beings that wish our harm and destruction; the implications of a universe peopled with gods who are either indifferent to our existence or hostile to it would have dramatic consequences, I think, culturally. Proof the universe doesn't care about people -- an ugly bit of nastiness but as possible as god being this wonderful and benevolent force in a fantasy game.)
Then there's the decision of what do these pesky outsiders really know? In a fair bit of fiction, technological advances have come from the mouths of demons. Would that be the case in this modern setting? Would researchers be nothing more than magicians with a ton of spells for getting information out of outsiders? If the answer is that outsiders are either not more technological advanced than humans -- which has interesting implications on its own, that we can do things better than angels and demons -- then, clearly, this question is void. If the answer is, yeah, these outsiders are better at technology than us and can be induced to part from their secrets, how humans interacted with science and technology would be radically different.
The political affiliations of outsiders could also be vitally important, of course. I mean, if the Angel Council endorsed a candidate -- y'know, a council of lawful good celestials -- who wouldn't vote for the person? And if people DIDN'T vote for that person, what does that say about the culture's values?
Even if outsiders didn't help scientific inquiries, if magic has been around for a while, certainly it would assist in the advance of science. Lots of experiments that people had to wait a long time to do -- so instruments of measurment and power were available -- could be done much earlier than in our world. I mean, would it have taken until Leo da Vinci to find the moons of Jupiter of eyes of the eagle were made in Roman days, for instance?
Likewise, how easily one could access other planes, and the nature of these planes, would be very important. If it was easy to get to the Great Wheel, for instance, would anyone be left on earth at all? Who would stay on earth if one could get admittance to Ysgard or Mt. Celestia? And what a learning experience it would be for people, who believe they are good and wonderful people, but who cannot endure the goodness of Mt. Celestia!
Controlled access to the Outer Planes would be easier on the game, naturally.
All these things are vital, absolutely vital, to understanding the impact of magic on the real world. Probably more important than the individual spells, themselves. Magic, arcane and divine, opens humanity up to all sorts of new possibilities.
The way magic operates will be important, too. Pretty clearly, if magic exists objectively, it's going to be the subject of massive scientific inquiry. Massive. Until it was well explored, described and manipulated it would be THE field of inquiry, I suspect. How opaque magic is to science is incredibly important; if science can "figure out" how magic works, and manipulate magical forces with that knowledge, it is possible there would be magic factories and the like. The implications of that would also have to be explored -- is there magical pollution?
Not to mention all the possible variants. Maybe the "gods" are mortal beings with superscience, and the spells are nothing but their bizarro world technology. Maybe the gods are gamers and we are their pieces and the universe is their rule-book -- the characters might never learn it, or believe it, but it could be true, just the same. It goes on and on.
The level of acceptance of magic is probably highly dependant on the length of time it's been around. Sure, there would be some skeptics for a while if magic arrived on the scene today. If it appeared a century, or an age, ago, it would be as accepted universally. I suspect if there were modest amounts of spellcasters, too, that most people would accept through the mechanism of "seeing is believing" that something was going on. Maybe they'd define it as "psionics" or conspiracy superscience whatever, but on some level the'd believe it because they can directly experience it.
Oh, yeah, conspiratologists would be in the Seventh Heaven with this stuff. I mean, a world were there WERE demons?! They'd have joygasms. Nothing could be proven, or disproven, all would be a jumble . . . .
In a modern world, I'm having trouble seeing how spellcasters would face systematic persecution. Spellcasters at ever level of society would probably help every level of society, so cultures that embraced spellcasters would have a huge advantage on those who didn't. Of course, other people might see differently than I do, but in terms of oppressor and oppressed, I figure that spellcasters would be overwhelmingly the oppressors not the oppressees. This would be more true if spellcasters have been around a while.
One of the more comprehensible, to me, possibilities of magical oppression is if one group of spellcasters for some reason was antithetical to the other -- let's say that the verifiably proven one true god tells his cleric and paladins (or blackguards, who might not realize they're evil, heh) that arcane spellcasters get their energy from evil forces. The truth of it would be irrelevant -- the religious folks would persecute arcane spellcasters because god told them to do so, and since they'd be backed up with the full weight of clerical magic victory of the magicians would not be assured.
Of course, if the magic was secret, part of a game about Secret Masters of the Illuminati or whatever, most of the effects on society could be ignored for a variety of reasons, the biggest being it's all hidden. ;p
Oh, the mind still reels! But I'm done with this letter.
Aside from the sheer irritation, it always pins the needle on my "moral outrage" meter.
