Maybe it is my lack of ability to understand english text.
Like Ive heard it before:
I agree we disagree.
No problem.
The discussion did bring up an interesting question though. Within the existing rules I can find no way for a mage to summon spirits outside his tradition, but the tradition is simply a mental framework that forms the mages understanding of magic it is not something that irrevocably alters the magicians soul. A magician should therefore theoretically be able to both study the frameworks of other traditions, as in studying other scientific disciplines, or even adopt a new tradition. This means that a magician should be able to learn how to summon spirits outside his tradition.
While the more religion-like traditions, the above mentioned zoroastrian faith for example, might consider it bad form, or even heresy, to do so, the scientific minded ones, like hermeticism, would most likely consider it a natural development of their studies.
Either:
a) You can never change your outlook on magic, once you choose a tradition you are stuck with it for the rest of your life. IMO this sounds like a boring solution.
b) While following a given tradition you are unable to summon spirits outside of that tradition. This means that anyone believing that magic is based on application of knowledge (hermetics, chaos magicians) are just plain wrong. Since this is so easy to discover, anyone following these traditions would be an idiot. Therefore this is a bad idea.
c) You can summon spirits outside your tradition if you have the knowledge. This makes the religious-minded traditions just as stupid as the scientific ones would be if "b" were true, also a bad idea.
Wierd that I'd never even considered this problem before