Magery as an improvable advantage?

[Anaraxes]

Originally Posted by hal

I treat Magery 1 as much an inborn trait as Magery 2 is. If you don't start with Magery 2, you're stuck with what you had at the start of the campaign.

Then you have your definition for that setting. An unchangeable value fixed at character creation (barring extreme magic) is one of the options covered early on upthread. Certainly that occurs often enough in the source literature.

So, yes. I'm looking for the rationale as to how spending 10 points to raise magery 0 after start of play to magery 1 has an IN GAME explanation for how it occurs.

Why, if you've got the definition that you like? By definition, that can't occur, so there is no such rationale.

Other settings don't have to have that assumption built in. It doesn't make sense to me to demand a rationale to convince you otherwise for your own game, particularly if you've already made up your mind that there cannot be any such acceptable rationale. Play your game the way you want. There's no GURPS police that will come along and force you to stop because you're Doing It Wrong. And if other people are playing under other assumptions, that's okay, too.