Er... really?
For the sake of argument, let's assume that in later chapters we will discover that Harry's future goes according to the plan he lays out... that is, at T1 Minerva sends her Patronus, and at T2 Harry gets out of Azkaban and travels to T1.
So at T1 Harry is in Azkaban and in Mary's Room.
If the Patronus finds Harry in Azkaban (as we've read), Harry travels to T1 in order to be found by Minerva, as you say.
But if the Patronus finds Harry in Mary's Room (as you're arguing couldn't happen), then Harry travels to T1 for some other reason, or no reason at all.
"But then there's no actual motivation for Harry's action!", I hear someone object. "No fair!"
Well, I agree. Similarly, by this theory, there's no actual motivation for the Patronus' choice.
"Because it would cause a paradox" is a little bit like "Because it would violate conservation of energy"... it's a reason to predict one consequence over another, but it isn't actually an explanation.
Of course, I will admit that I am confused about what local laws could add up to the "no paradox" global law.
- This thread has run its course. You will find newer threads in the discussion section.
Another discussion thread - the fourth - has reached the (arbitrary?) 500 comments threshold, so it's time for a new thread for Eliezer Yudkowsky's widely-praised Harry Potter fanfic.
Most of the paratext and fan-made resources are listed on Mr. LessWrong's author page. There is also AdeleneDawner's collection of most of the previously-published Author's Notes.
Older threads: one, two, three, four. By tag.
Newer threads are in the Discussion section, starting from Part 6.
Spoiler policy as suggested by Unnamed and approved by Eliezer, me, and at least three other upmodders:
It would also be quite sensible and welcome to continue the practice of declaring at the top of your post which chapters you are about to discuss, especially for newly-published ones, so that people who haven't yet seen them can stop reading in time.