In ch71 he even refused to say "I solemnly swear I'm up to no good" for that reason, so that's at least reason to think he claims to be a principled truth teller. And generally his behaviour seems consistent with that to me, like when he was teaching Harry obfuscation without lying, in ch18 when they were having their round of bargaining/blackmail over Snape's behaviour, or his reaction after Harry pressed him on the matter of whether he killed Narcissa Malfoy.
Of course he could be willing to lie for sufficiently important reasons just like Harry (though Harry ended up that way under Quirrel's influence), but I see no really pressing reason for that here, and if it comes out that the note is from him, Harry could call him on it.
It seems transparent to me that the whole thing with the cloak was a gambit to manipulate Harry. Harry's trust in the note-sender's warning, followed by Dumbledore's noble and forgiving reaction, caused Harry to feel guilty for doubting Dumbledore, and to tend towards trusting him more and trusting people who told him to doubt Dumbledore less.
If Dumbledore was playing both sides (and thus lying his head off), he achieved his real objective (to make Harry trust him more) very elegantly.
New chapter, and the end is now in sight!
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 103.
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: