Yes, but... just for the sake of argument...
Flamel is an inventor. And when assigning confidence in statements he makes about Philosopher's Stones, you need to bear in mind that he's the only inventor dumb enough to get caught. Anyone who independently invented it before him (or after) managed to keep it secret, that's all.
Or maybe there's more than one way to create a Philosopher's Stone and Flamel discovered the most difficult, so now he has an inflated idea of how hard it would be for someone else to duplicate his feat.
Or possibly Flamel is the Dread Pirate Roberts and there's no such thing as a Philosopher's Stone at all.
I'm not sure which explanation I like more, actually.
The Philosopher's Stone would be phenomenally useful to Quirrelmort, and if it weren't really hard to get, he would presumably already have one. After all, if there's anyone with an incentive to find the easiest way to get their hands on one, it's him.
As for the Philosopher's Stone not being real, I doubt Dumbledore would have gone to such lengths to guard it if he weren't convinced it was, and I doubt tricking him into buying into a fake would be easy.
(The HPMOR discussion thread after this one is here.)
The previous thread is over the 500-comment threshold, so let's start a new Harry Potter and the Methods of Rationality discussion thread. This is the place to discuss Eliezer Yudkowsky's Harry Potter fanfic and anything related to it. The latest chapter as of 09/09/2011 is Ch. 77.
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: one, two, three, four, five, six, seven, eight. The fanfiction.net author page is the central location for information about updates and links to HPMOR-related goodies, and AdeleneDawner has kept an archive of Author's Notes.
As a reminder, it's often useful to start your comment by indicating which chapter you are commenting on.
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: