Magic is, in the end, zero-sum.
Doesn't Harry spend at least the first half of the story being variously shocked and outraged at how magic does not abide by the laws of thermodynamics? See Aguamenti producing water out of nothing.
Even the laws governing potions aren't really a case of equivalent exchange: the heat of the Ashwinder eggs disperses into the surrounding environment and is bestowed upon any potion made using them.
Yeah, different bits of magic seem to operate on different conservation laws, it's true. And they aren't the ones of physics. But Quirrell seems to expect value to be conserved — and therefore, that accumulating value to yourself and your allies logically implies depriving others of value — whereas Harry seems to expect otherwise.
New chapter!
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 104.
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: