Yes, you can. Miracle allows you to play it (typically) in your draw step, a time when you couldn't normally play sorceries anyway. In other words, it allows you to ignore the timing restrictions.
From the Avacyn Restored FAQ:
* You cast the card with miracle during the resolution of the triggered ability. Ignore any timing restrictions based on the card's type.
* You can reveal and cast a card with miracle on any turn, not just your own, if it's the first card you've drawn that turn.
No - you have permission to cast something from exile, but not permission to ignore timing.
So yes, there are different types of permissions in that permission to do one thing is not a blanket allowance. You have to have permission to do all the things.
The rules give you permission to cast a sorcery during your main phase while the stack is empty and you have priority. Normally, that means you don't have permission on other players turns to do so, but there's no restriction disallowing it rather it's just a lack of permission.
Does this mean there are different types of permissions? I don't know where it's covered in the rules, but the way I learned it is that when an effect says you may cast the spell right now (during resolution), you ignore timing restrictions. But when the effect says you may cast the spell "whenever" (like, until end of turn, or while it's exiled), you don't ignore timing restrictions.
Say, you tap Nivix, Aerie of the Firemind on an opponent's turn, exiling Preordain. You did get some form of permission but you still can't cast it.
Nivix gives you permission to cast Preordain from exile (a zone you don't normally have permission to cast it from), but it doesn't give you any permission on when to cast the spell, so you use the default timing permissions set up by the game rules. The Miracle ability gives you permission to cast the spell as part of the resolution of the Miracle trigger.
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From the Avacyn Restored FAQ:
* You cast the card with miracle during the resolution of the triggered ability. Ignore any timing restrictions based on the card's type.
* You can reveal and cast a card with miracle on any turn, not just your own, if it's the first card you've drawn that turn.
So yes, there are different types of permissions in that permission to do one thing is not a blanket allowance. You have to have permission to do all the things.
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