Epistemic status: Hortative. I'm trying to argue for carving reality at a new joint.
I think it's lovely and useful that we have labels, not just for rationalist, but for rationalist-adjacent and for post-rationalist. But these labels are generally made extensionally, by pointing at people who claim those labels, rather than intensionally, by trying to distill what distinguishes those clusters.
I have some intensional definitions that I've been honing for a long time. Here's the biggest one.
A rationalist, in the sense of this particular community, is someone who is trying to build and update a unified probabilistic model of how the entire world works, and trying to use that model to make predictions and decisions.
By "unified" I mean decompartmentalized- if there's a domain where the model gives two incompatible predictions, then as soon as that's noticed it has to be rectified in some way.
And it's important that it be probabilistic- it's perfectly consistent to resolve a conflict between predictions by saying "I currently think the answer is X with about 60% probability, and Y with about 25% probability, and with about 15% probability I'm missing the correct option or confused about the nature of the question entirely".
The Sequences are aimed at people trying to do exactly this thing, and Eliezer focuses on how to not go horribly wrong in the process (with a special focus on not trusting one's own sense of obviousness).
Being a rationalist isn't about any specific set of conclusions- it's not about being an effective altruist, or a utilitarian, or even an atheist. It's about whether one is trying to do that thing or not. Even if one is doing a terrible job of it!
Truth-seeking is a prerequisite, but it's not enough. It's possible to be very disciplined about finding and assembling true facts, without thereby changing the way one thinks about the world. As a contrast, here's how the New York Times, whose fact-checking quality is not in dispute, decides what to report:
By and large, talented reporters scrambled to match stories with what internally was often called “the narrative.” We were occasionally asked to map a narrative for our various beats a year in advance, square the plan with editors, then generate stories that fit the pre-designated line.
The difference between wielding a narrative and fitting new facts into it, and learning a model from new facts, is the difference between rationalization and rationality.
"Taking weird ideas seriously" is also a prerequisite (because some weird ideas are true, and if you bounce off of them you won't get far), but again it's not enough. I shouldn't really need to convince you of that one.
Okay, then, so what's a post-rationalist?
The people who identify as such generally don't want to pin it down, but here's my attempt at categorizing at least the ones who make sense to me:
A post-rationalist is someone who believes the rationalist project is misguided or impossible, but who likes to use some of the tools and concepts developed by the rationalists.
Of course I'm less confident that this properly defines the cluster, outside of groups like Ribbonfarm where it seems to fit quite well. There are people who view the Sequences (or whatever parts have diffused to them) the way they view Derrida: as one more tool to try on an interesting conundrum, see if it works there, but not really treat it as applicable across the board.
And there are those who talk about being a fox rather than a hedgehog (and therefore see trying to reconcile one's models across domains as being harmful), and those who talk about how the very attempt is a matter of hubris, that not only can we not know the universe, we cannot even realistically aspire to decent calibration.
And then, of course:
A rationalist-adjacent is someone who enjoys spending time with some clusters of rationalists (and/or enjoys discussing some topics with rationalists), but who is not interested in doing the whole rationalist thing themself.
Which is not a bad thing at all! It's honestly a good sign of a healthy community that the community appeals even to people for whom the project doesn't appeal, and the rationalist-adjacents may be more psychologically healthy than the rationalists.
The real issue of contention, as far as I'm concerned, is something I've saved for the end: that not everyone who self-identifies as a rationalist fits the first definition very well, and that the first definition is in fact a more compact cluster than self-identification.
And that makes this community, and this site, a bit tricky to navigate. There are rationalist-adjacents for whom a double-crux on many topics would fail because they're not interested in zooming in so close on a belief. There are post-rationalists for whom a double-crux would fail because they can just switch frames on the conversation any time they're feeling stuck. And to try to double-crux with someone, only to have it fail in either of those ways, is an infuriating feeling for those of us who thought we could take it for granted in the community.
I don't yet know of an intervention for signaling that a conversation is happening on explicitly rationalist norms- it's hard to do that in a way that others won't feel pressured to insist they'd follow. But I wish there were one.
A related thing I was thinking about for some time: Seems to me that the line between "building on X" and "disagreeing with X" is sometimes unclear, and the final choice is often made because of social reasons rather than because of the natural structure of the idea-space. (In other words, the ideology is not the community; therefore the relations between two ideologies often do not determine the relations between the respective communities.)
Imagine that there was a guy X who said some wise things: A, B, and C. Later, there was another guy Y who said: A, B, C, and D. Now depending on how Y feels about X, he could describe his own wisdom as either "standing on shoulders of giants, such as X", or "debunking of teachings of X, who was foolishly ignorant about D". (Sometimes it's not really Y alone, but rather the followers of Y, who make the choice.) Two descriptions of the same situation; very different connotations.
To give a specific example, is Scott Alexander a post-rationalist? (I am not sure whether he ever wrote anything on this topic, but even if he did, let's ignore it completely now, because... well, he could be mistaken about where he really belongs.) Let's try to find out the answer based on his online behavior.
There are some similarities: He writes a blog outside of LW. He goes against some norms of LW (e.g. he debates politics). He is admired by many people on LW, because he writes things they find insightful. At the same time, a large part of his audience disagrees with some core LW teachings (e.g. all religious SSC readers presumably disagree with LW taking atheism as the obviously rational conclusion).
So it seems like he is in a perfect position to brand himself as something that means "kinda like the rationalists, only better". Why didn't this happen? First, because Scott is not interested in doing this. Second, because Scott writes about the rationalist community in a way that doesn't even allow his fans (e.g. the large part that disagrees with LW) to do this for him. Scott is loyal to the rationalist project and community.
If we agree that this is what makes Scott a non-post-rationalist, despite all the similarities with them, than it provides some information about what being a post-rationalist means. (Essentially, what you wrote in the article.)
Scott could do all those things and be a rationalist-adjacent. He's a rationalist under my typology because he shares the sincere yearning and striving for understanding all of the things in one modality, even if he is okay with the utility of sometimes spending time in other modalities. (Which he doesn't seem to, much, but he respects people who do- he just wants to understand what's happening with them.)