My thoughts: 1) It's becoming increasingly clear that - even though Harry has accumulated a wealth of knowledge and evidence by this point about Dumbledore, Quirrell, Lucius and Snape - he still knows little about Voldemort (e.g. motives, background, abilities, weaknesses). I am fairly confident that this is intentional on the author's part; withholding Harry's (and the reader's) knowledge about Voldemort is an excellent way to ensure that a Revelation of information occurs within the next few chapters about Voldemort's background. 2) We haven't yet seen Harry's reaction to the fact that Flitwick invented a Charm; presumably he will update his model of the nature of magic when he has time to process this. 3) The joke at the beginning of the chapter making fun of America's disconnect with the rest of the world was particularly brilliant and appreciated

Shir L'Or

Nice use of Hebrew.

So... if there is a 10% chance that there will be a 25% cost overrun, and a 90% chance that the unexpected expenses will fall within the contingency budget, should the budget be 125% projected cost, or 102.5% projected cost?

Which is entirely the wrong way to go about the problem. If this project is critical, and it's failure will sink the company, you really, really want to be in a position to handle the 25% cost overrun. If you have ten other identically-sized, identically-important project, then the 102.5% estimate is probably going to give you enough of a contingency to handle any one of them going over budget (but what is your plan if two go over budget?)

Thinking in terms of statistics, without any actual details attached, is one of the BIG failure modes I see from rationalists - and one that laypeople seem to avoid just fine, because to them the important thing is that Project X will make or break the company.

Keep in mind that meetings will expand to fill the allocated time, even if they are completed before then, and projects will tend to use their entire budget if possible.

I'd suggest that this is a solvable problem - I've worked in multiple offices where meetings routinely ended early. Having everyone stand helps a lot. So does making them a quick and daily occurrence (it becomes routine to show up on time). So does having a meeting leader who keeps things on-topic, understands when an issue needs to be "taken offline" or researched and brought up the next day, etc..

It amuses me that the Less Wrong community refers to itself as "rationalist," given that at one point in intellectual history, "rationalists" were those who did not believe in empiricism.

Are you referring to Humean rationalists? Before Hume used empiricism to show how by mere empiricism one can never certainly identify the cause of an effect, empirical thought was lauded by Cartesian rationalists. Hume's objection to an overreliance on empiricism also (partially) helped galvanize the Romantic movement, bringing an end to the Enlightenment. Future individuals throughout history who considered themselves rationalists were of the Cartesian tradition, not 'all is uncertain' Humean rationalism (see Albert from Goethe's The Sufferings of Young Werther for one example). Those who embraced Hume's insight, though it should be mentioned that Hume himself thought that fully embracing same would be quite foolish, did not call themselves rationalists, but were divers members of myriad movements across history.

Hume's point remained an open problem until it was later considered solved by Einstein's theory of special relativity.

Welcome, by the way.

Hi everyone!

I'm 19 years old and a rising sophomore at an American university. I first came across Less Wrong five months ago, when one of my friends posted the "Twelve Virtues of Rationality" on facebook. I thought little of it, but soon afterward, when reading Leah Libresco's blog on atheism (she's since converted to catholicism), I saw a reference to Less Wrong, and figured I would check it out. I've been reading the Sequences sporadically for a few months, and just got up to date on HPMOR, so I thought I would join the community and perhaps begin posting.

Although I have little background in mathematics, cognitive science, or computer programming, I have had a long-standing, deep interest in ethics and happiness, both of which inevitably lead to an interest in epistemology. Since I began hanging around Less Wrong, my interest in logic and cognitive biases has definitely been piqued as well. Some of my other, less relevant, interests include intellectual history, music, Western classic literature, literary theory, aesthetics, economics, and political philosophy. I also enjoy the New York Giants and playing the piano.

I love debating others, but mostly debating myself - I do so constantly, but too often inconclusively. The main advantage I've found of debating others is that they help disabuse me of my own self-deceptions. Reading good literature usually serves this purpose as well.

A strong part of my identity is that I am a religious Jew. I am not a theist, but I keep a large portion of Jewish law, mostly because I am satisfied that doing so is a good use of my time. I can't remember a case when Jewish law has collided with my ethics, perhaps because so many of my ethical intuitions come from the Jewish tradition.

It amuses me that the Less Wrong community refers to itself as "rationalist," given that at one point in intellectual history, "rationalists" were those who did not believe in empiricism. Aside from that, I'm extremely excited to learn from all of you.