(Psi)SeveredHead
Adventurer
Actaully, in the real world, giftedness offcially begins at 130 (mathematical reasons: 2 standard deviations), and covers exactly 2.5% of humanity.
Alright. Thought it was 140, as that's what I needed.
Turning IQ into Int the way you suggest gives the problems at the low end: by your reasoning, IQ50 would equal Int 0, which is obviously wrong.
I would stop at Int 3, which is an IQ of around 65, which would mean the character is mentally challenged, but still more than a 30.
Int below 3 needn't be considered, as that's animal level. (Or at least chimp level. Chimps are supposedly as smart as 5 year old human children.)
As for an Int11 bad guy being too dumb: given that the average IQ of university students is just below 120 (Int12 in my reckoning), I think he'd be doing ok; most illegal work does not require a degree.
But Gotti was the boss, and smarter than most of his mobsters. Gotti didn't have a degree, that's pretty rare in a mobster, but intelligence includes more than just education. He certainly demonstrated it by staying ahead of the police for quite a while. (He did get caught in the end though. Relying on people who can't keep their mouths closed was some sort of character flaw with him.)
By my reckoning, a typical university student would need an Int 14, which is getting rare in 3d6 random rolls system, but so many people have university degrees these days. It's certainly something for me to think about.
As regarding this thread, these magic crafters are essentially university students. Their tests might require a series of Intelligence checks (say, one per month or year) that a person with Int 12 or 14 would make half the time, and they need to make half those checks to pass. That would over time weed out those who don't measure up, even if they could (within the rules) be able to cast very low-level spells.
On another note, I'm recalling a feat in Forgotten Realms for the people of Halruua, a magical human nation. There's a "background" feat that requires Int 10 and lets you cast a few cantrips. Somewhere it said a third of the population had it. (Since half the population has Int 10 or more, one wonders why more don't have it.)