Hi everyone, I have recently started reading this site again after having had a break for a couple years.

What I like most about LessWrong (apart from the name), is that it contains so much good quality information about rationality, all in one place. And the posters maintain such a high standard of reasoning. One thing I would like to see more of on the site, though, is analyses of common human behaviour.

Also, it would be great to see some humour on here.

Hi! I'm Hazrina from Indonesia. I came here after reading Harry Potter and The Methods of Rationality and googling about the author. I'm a total newbie in this rationality thingy and I'm looking forward to learn a lot here. Thank you so much for making this wonderful community 🌻

Greetings. Retired engineering type from Central New Jersey, USA. From my quick first scan I can tell I will be spending some evenings in front of the screen learning and appreciating other opinions on a wide area of topics.

Radio Bob

Hello Everyone.
I am new to lesswrong and am keen on exploring a structured approach to rationality. I am fascinated by mathematics and keep wondering if we can have similar formal methods for thinking about life. 

Hello! I have been exploring LessWrong on a non-regular basis for a few months, and have recently been advised to create my own account.

I am a french aerospace student, who will (likely) start a PhD next year. I am particularly interested in mitigating xrisks, and would like to orient my career in such a direction. I enjoy ethics, epistemology, and philosophy of mind. A fact which I think is relevant: I am probably a bit less fond of bayesianism as most people here.

I'm looking for a comment from /u/wei_dai; it had something to do along the lines of deciding what to work on (or do, or study) week by week, and then updating/changing after the week (maybe in a post about UDT?) Does someone know what I'm talking about? Search function, wei_dai posts and google has turned up nothing. Thanks for anyone's help!

There's a post somewhere in the rationalsphere that I can't relocate for the life of me. Can anybody help?

The point was communication. The example given was the difference between a lecture and a sermon. The distinction the author made was something like a professor talking to students in class, each of whom then goes home and does homework by themselves, versus a preacher who gives his sermon to the congregation, with the expectation that they will break off into groups and discuss the sermon among themselves.

I have a vague memory that there were graphics involved.

I have tried local search on LessWrong, site search of LessWrong, and browsing a few post histories that seemed like they might be the author based on a vague sense of aesthetic similarity. I was sure it was here, but now I fear it may have been elsewhere or it is hidden in some other kind of post.

Whence I come: 78 years old, Ph. D. social psych, musician, lately reading a lot of philosophy. Just wondering if the community here thought Hume was an idiot and the latest findings about emotions being a necessary part of decision-making horrifying. bill w

is there any explanation of the current Karma System? The main thing I can find is this. (you need to scroll to 'The karma system', for some reason you can click on subsections to go to them, but you can't link to them).

Also why do I see a massive message that says 'habryka's commenting guidelines' when I am writing this comment, but there are no guidelines or link? Is this just a weird extra ad for your own name?

I'm (re-)reading up on absolutely continuous probability spaces right now. The defintion for the expected value I find everywhere is this:

(1): $E\left(X\right):={\int }_{-\infty }^{\infty }x\cdot f\left(x\right)\text{d}x$

The way to interpret this formula is that we're integrating over the target space of $X$ rather than the domain, and $f$ is a probability density function over the target space of $X$. But this formula seems highly confusing if that is left unsaid ($X$ doesn't even appear in it – what the heck?). If one begins with a probability density function $f$ over a probability space $\Omega =R$ and then wants to compute the expected value of a random variable $X:\Omega \to R$, I think the formula is:

(2): $E\left(X\right):={\int }_{-\infty }^{\infty }X\left(\omega \right)\cdot f\left(\omega \right)\text{d}\omega$

It seems utterly daft to me to present (1) without first presenting (2) if the idea is to teach the material in an easily understandable way. Even if one never uses (2) in practice. But this is what seems to be done everywhere – I googled a bunch, checked wikipedia, and dug out an old script, I haven't found (2) anywhere (I hope it's even correct). Worse, none of them even explicitly mention that $x$ ranges over $X\left(\Omega \right)$ rather than over $\Omega$ after presenting (1). I get each random variable does itself define a probability space where the distribution is automatically over $X\left(\Omega \right)$ but I don't think this is a good argument not to present (2). This concept is obviously not going to be trivial to understand.

Stuff like this makes me feel like almost no-one thinks for themselves unless they have to, even in math. I'm interested in whether or not fellow LW-ians share my intuition here.

There seems to be a similar thing going on in linear algebra, where everyone teaches concepts based on the determinant, even though doing it differently makes them far easier. But there it feels more understandable, since you do need to be quite good to see that. This case here just feels like people aren't even trying to optimize for readability.