How do you write original rationalist essays?

Interesting! I am not quite sure what exactly you want to point towards. For example, I've been very impressed when people like Elizier or Scott came up with concept handles for things like Generalization from Ficional Evicence [LW · GW]. But I am not sure this is the kind of "original thought" you mean.

Can you give 1 example of a train of thought in a post that impressed you in a way that you didn't feel like you could produce something qualitatively similar? Or do you feel like this would be hard to do because the kind of "originality" your talking about is more expressed in how it fits into the overarching worldview of a person? Or something else?

most of these thoughts are something they just came up with, not something they have learned elsewhere.

Note that there's some pressure on authors to make it seem like this even when it's not. For one thing it makes them seem smarter, and for another it's easier to make the text flow better. (Especially if the source isn't "I learned this from this specific person and you can read their book here" but "I picked this up from various conversations with people whose names I don't remember".) I expect if you could see how the sausage was made it would seem less original than it does now. That's not to accuse anyone of deliberately hiding their sources, and it's not even necessarily a bad thing. (Note that flow is good and irrelevant info is bad.)

I think EY's admitted that the sequences come across more original than they are, and I think Scott recently wrote a note like "the worms hypothesis from my last post is not original to me".

For another facet of practicing creativity, check out the Babble and Prune sequence [? · GW] if you haven't seen it yet. I particularly liked this [? · GW] and this [? · GW] post.

1. There's nothing wrong with doing research.

2. Even if there was one trick that worked, it might take a while to explain. Both of them might have writing advice.

3. What do you want to write about?

I can teach, I can write short fiction, but can't write this type of essays either.

My problem is that teaching and fiction seem like opposites. Fiction is just some random bullshit, written in an entertaining way. Teaching is like solving a puzzle. Fiction does not require any special knowledge (on reader's side). Teaching, at best, is tailored to student's current knowledge, so the first step is to figure out what your student already knows and knows not.

In an essay, you kinda do all of this at the same time. You have a topic, you make some funny sidenotes, but don't lose the main topic. You expect your audience to already know some basic things, to already think in certain ways (to accept a certain type of argument). You aim to be technically correct, but to keep a conversational style.

I find this somewhat easier to do when talking than when writing. At least, when I say something, I can't take it back anymore; I have to continue. When I start writing, you will usually find me one hour later, still revising the first sentence of the first paragraph. (So, maybe, talk and record yourself at home?)

But gun to my head - I can't seem to just sit down and make up an original non-fiction essay worthy of Less Wrong

With a gun to your head you would. It's amazing what the right motivation can do.

You seem to be asking how you can deliberately and effortfully practice your writing. Did Scott and Paul Graham get to where they are by deliberately and effortfully practicing their writing? Are there people like them who did? One thing that has stuck in my mind from an old Paul Graham essay:

One of the most dangerous illusions you get from school is the idea that doing great things requires a lot of discipline. Most subjects are taught in such a boring way that it's only by discipline that you can flog yourself through them. So I was surprised when, early in college, I read a quote by Wittgenstein saying that he had no self-discipline and had never been able to deny himself anything, not even a cup of coffee.

If you are an autodidact who has to make do with studying textbooks on your own, a place to start with this would be Baronett's Logic and Wright's Critical Thinking: An Introduction to Analytical Reading and Reasoning.

If you want to have interesting ideas, the key thing is to inform yourself widely and deeply in the details of the subject matter you want to have interesting ideas about. Interesting ideas come naturally out of this work of studying the material. Conveniently, reading a lot for this sake often satisfies the above requirement to read a lot so that you're a better writer, so that you can often get two birds with one stone here.