Nope.
Also, it would have been a standard rule only in 3e.
I think you're wrong, two others in this thread have said you're wrong, so I checked the d20 SRD. And yup, you're wrong. That's how 3e stands as standard now. At some point earlier it was different, but eventually the standard became that psionics had that connection to magic.
So, while you may ignore "tradition" the game should not if they are trying to recapture a specific feeling of how something is supposed to work.
It's no longer even clear what the tradition is, given it was sometimes considered magic and sometimes not. And as I said, the original tradition had it intermingled with Deryni magic repeatedly, which was also considered magic. So, it doesn't seem to me the tradition is clearly "psionics isn't magic". It seems like sometimes it was, sometimes it was not, and nobody really knew what it was.
A. I agreed with you that sorcerers should be psionic in such a case.
{I moved this part up in the conversation for relevance}
OK, so we've established that tradition on this sort of topic isn't very persuasive, since you're fine to break with tradition on this sort of thing when it comes to one previously arcane class.
SO, we can discard with the "It's tradition" argument. We're left with "What are the persuasive reasons to have these three sources of power?"
So, the purpose is to streamline. Okay, why not ONE type of magic, or not specifying at all. Magic just is magic in our world after all. All magic (in our real myths) comes from the gods/nature/spirits, or from demons/the soul/blood. That could be our baseline. As @KM says that would make ALL casters divine classes, which I'm okay with. But then you still have a problem as psionics isn't divine magic.. but I'll get back to that.
I'd be OK with one type of magic. But the two-types IS a well defined tradition. Even in fantasy tropes, two types of magic is a well-known thing in fantasy settings. Three, however, is not.
So is psionic (not magic) vs. magic. One is spell-like and the other is spells.
Spells are by definition spell-like. I see no difference here.
One works in an antimagic field, one does not.
So we're defining an entire type of magic based on the effects a couple other spells have on them? Wouldn't it make MUCH more sense to simply put that in the spells we're talking about?
One can be dispelled, detected and otherwise countered as magic. One cannot.
Well, in some editions, and not in others, but again this is so few spells it would be much more efficient to put it in the spell descriptions rather than justify an entire class structure and source of magic because of a few spells.
That has nothing to do with tradition or "because" of how the effect works. It does semi come down to those things when you think why they are spell-like abilities but I'm not going into that.
Those you just named are purely tradition. Why can't you detect psionics with detect magic in some editions and not others? Because they were different. Why were they different? Because the books said so - no real reason beyond simply the books stating you cannot detect psionics with detect magic, unless you could, depending on the edition. None of that is a reason why they are different, it was simply a (weak) tradition stating they were.
Arcane magic is magic from an arcane source.
I know what a divine source means, it's right there in the meaning of the word "divine". I do not know what an "arcane" source means. It's not there in the definition of the word "arcane". Arcane just means "understood by few; mysterious or secret.". That's it. That's not specifying what the source is, in fact it's saying "mysterious source". So I'll ask again, what is the "arcane" source, and given it's just a mysterious source, why can't that be the same source for psionics?
Typically this magic comes from years of training and is gained through knowledge of arcane power through magical sigils (spellbooks), innate magical power (bloodlines), or deals with powerful beings (pacts).
Psionics is spell-like abilities from a mental source. Typically it manifests as "mind-powers" which cannot be counted as spells and are NOT magic.
I've already dealt with the "not magic" part (some editions it's magic, some not. Some traditions it's magic, some not).
Sorcerers don't study, but wizards do, and both are considered arcane. Innate magic power is the same as psionics, which are also innate powers in all editions of the game. Sorcerers are specifically spontaneous casters with the innate power to use magic by force of their willpower. How is that different from mindpower? What is willpower, if it's not mindpower? Willpower just means, "the faculty by which a person decides on and initiates action." How is that different from mindpower, which is, "the element of a person that enables them to be aware of the world and their experiences, to think, and to feel; the faculty of consciousness and thought." Those are pretty darn close to synonyms.
And if sorcerers are close enough to psionics to be basically the same, then the tradition argument goes out the window because tradition is already clearly on the side of sorcerers being arcane magic. So then the argument comes down to "Arcane magic is non-divine studied magic, and Psionics is non-divine and non-studied magic". Which I will grant you is a distinction, but it seems a pretty silly one. It means a studied psionics class would need to be arcane, and a studied divine class would need yet a fourth source of magic (divine non-spontaneous), and the silliness of this distinction for sources of magic becomes more stark. Whether or not you study a magic should have no baring on where that magic is sourced to.
Even in 3e (which seems to be the edition you are most familiar with?)
I've played all editions except 2e. My most recent continual edition prior to the 5e playtest was 4e. So no. I am not mentioning 4e because, due to the structure of 4e, EVERYTHING could essentially have it's own source of power because there was no real unified system for siloing classes along these lines. Instead it had roles, which could include a fighter or a divine magic user or a skills-focused class or an arcane magic class or even a psionic-using class, and it all depended on their powers uses, rather than the sources of that power.
So, in sum, turning to 4e for guidance on this topic isn't useful in my opinion. Not that it wasn't a fine system, it just offers no real direction on a topic like this because it didn't really structure things based on sources anyway. You could have had a class with anti-power or smell-power for all they cared, and it would have worked just as well as any other source of power as the sources were fairly meaningless.
And in 1e, Psionics was a tacked-on system in the back of the book that extremely few used as a player, because the odds your character could even have psionics was extremely small, and most DMs simply dismissed it out of hand as superfluous stuff for most games. And it didn't even exist in OD&D, or Basic/Expert/Etc.
You aren't making the argument that sorcerers should be different are you? I mean you are, but I don't think you mean to be.
I am saying they're functionally the same as psionics, but that's proof psionics isn't really different from arcane, they're just different from STUDIED arcane, which as I explained earlier in this post is a pretty silly distinction to base a source of power on.
Success! Psions use mind-"magic", and don't memorize spells from books.
As I explained earlier, "mind-magic" is the same as "willpower magic". So you're trying to distinguish the sources of power based on whether or not it's innate power or studied. Which, as previously demonstrated, is silly and leads to ever more silliness as you draw it out to it's logical conclusion.
Psionics =/= arcane and divine, because psionics is sourced to the mind (and is not technically magic) and divine and arcane are not.
Except arcane or divine ARE sourced to the mind. There was a studied form of divine caster in a couple of editions, are they now their own power source? Sorcerer is of the mind, is that it's own power source too, or psionic, in which case why are we splitting psionics from arcane again other than this silly "did you study it?" distinction?
Just because you don't understand something doesn't mean it shouldn't exist. [sarcasm]*inserts clip of Bill O talking about the tides*[/sarcasm]
I am trying to drill down on the reasoning behind the distinction and importance for people. I get "It's tradition", but so far the rest seems to, at best, come down to "It's not studied magic, which means anyone who doesn't study their magic should also be using psionics, except when they shouldn't, maybe. Oh and there are three spells that don't interact the same with it, sometimes, maybe."