I think that links to Chapman's texts should contain some disclaimer that "rationality" as defined by Chapman is something completely different from "rationality" as defined by Less Wrong.

I am of many minds about this. Sometimes I feel as you've expressed; that Chapman undersells 'rationality' and misrepresents its possibilities. Certainly LW!rationality is (mostly) aware of his specific criticisms. But I still find his writing immensely insightful as-is. And given that his audience is very different than LW, I'm inclined to accept his writing as-is too.

As for him using 'rationality' differently – that general phenomena (of words being used differently by different people) is something that I'm all too aware of, among all the things I read and all the conversations I have. I certainly don't find his writing as painful to read as others.

And maybe we should add disclaimers to all of our pages pointing out that our use of 'rationality' is idiosyncratic (with respect to everyone else in the world). I don't think there's a good solution to this.

I agree that "The LW!rationality already contains its own meta." but I think Chapman has a point that meta-rationality is something distinct from ('regular') rationality. Hence the utility of a lot of the advice that both Chapman and the LW sequence writers provide.

Chapman warns people against going from straw rationalism to nihilism (unless they accept the Buddhism-inspired wisdom). But I don't see nihilism promoted on Less Wrong. We have "something to protect". And the stories of "beisutsukai" are obviously written to inspire.

Maybe that's missing from LW? I agree that LW doesn't promote nihilism, but maybe it should do more to help otherwise-intelligent people avoid it.

And more generally, (intelligent) people really do get stuck at "straw rationality" ("level 4"), i.e. 'trapped' in the specific formalisms of which they're aware and in which they can 'operate'. We don't worship science, but lots of other people sure seem to do so.

I think the best 'trick' LW!rationality incorporated into its 'canon' is the idea of instrumental rationality. Coupled with a consequentialism scoped to our 'entire future light cone', that idea alone acts like a source of intellectual free energy capable of pushing us out of any particular formalism when (we suspect) it's not good enough for our purposes. But it's not clear, to me anyways, that that itself is 'rational'. (It is LW!rational, obviously.)

Also, I'm not sure if "the Buddhism-inspired wisdom" was dismissive, but I really enjoy his writing about Buddhism (and it's mostly published on other sites of his). From what I've read of that, he's not a Buddhist – certainly not a 'traditional' (or folk) Buddhist. He seems mostly interested in very specific schools, has his own idiosyncratic interpretations, wants a better 'modern synthesis' drawing on his favored insights, and is actively experimenting with various practices for his own purposes. He definitely rejects 'woo' (and his favorite schools seem to be relatively light on that anyways). But there's a lot of insight available too. Just off the top of my head – the tantric Buddhist "practice of views" charnel ground and pure land. Traditional rationality, i.e. straw rationality, is pretty dismissive of emotions. LW!rationality is much better. Chapman is mining popular religion and philosophy, in particular the branches of Buddhism he likes, for interesting and sometimes-useful info, often pertaining to emotions and what to do about them.

So, ironically, from my perspective, it is like if straw rationality is level 4, and Chapman's "meaningness" is level 5, then Less Wrong would be level 6. (Yeah, I can play this game, too.)

How seriously are you playing this game (ha)? Somewhat seriously, we're definitely around (or aiming for) his level 5. You've pointed out a lot of 'meta-rational' advice from this site (and most that's several years old now too). What would level 6 be, to you (besides 5 + 1)?