I want to specifically object to the last part of the post (the rest of it is fine and I agree almost completely with both the explicit positive claims and the implied normative ones).

But at the end, you talk about double-crux, and say:

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.

Well, and why did you think you could take it for granted in the community? I don’t think that’s justified at all—post-rationalists and rationalist-adjacents aside!

For instance, while I don’t like to label myself as any kind of ‘-ist’—even a ‘rationalist’—the term applies to me, I think, better than it does to most people. (This is by no means a claim of any extraordinary rationalist accomplishments, please note; in fact, if pressed for a label, I’d have to say that I prefer the old one ‘aspiring rationalist’… but then, your given definition—and I agree with it—requires no particular accomplishment, only a perspective and an attempt to progress toward a certain goal. These things, I think, I can honestly claim.) Certainly you’ll find me to be among the first to argue for the philosophy laid out in the Sequences, and against any ‘post-rationalism’ or what have you.

But I have deep reservations about this whole ‘double-crux’ business, to say the least; and I have commented on this point, here on Less Wrong, and have not seen it established to my satisfaction that the technique is all that useful or interesting—and most assuredly have not seen any evidence that it ought to be taken as part of some “rationalist canon”, which you may reasonably expect any other ‘rationalist’ to endorse.

Now, you did say that you’d feel infuriated by having double-crux fail in either of those specific ways, so perhaps you would be ok with double-crux failing in any other way at all? But this does not seem likely to me; and, in any case, my own objection to the technique is similar to what you describe as the ‘rationalist-adjacent’ response (but different, of course, in that my objection is a principled one, rather than any mere unreflective lack of interest in examining beliefs too closely).

Lest you take this comment to be merely a stream of grumbling to no purpose, let me ask you this: is the bit about double-crux meant to be merely an example of a general tendency (of which many other examples may be found) for Less Wrong site/community members to fail to endorse the various foundational concepts and techniques of ‘LW-style’ rationality? Or, is the failure of double-crux indeed a central concern of yours, in writing this post? How important is that part of the post, in other words? Is the rest written in the service of that complaint specifically? Or is it separable?

In terms of conversation style, I'd define a "rationalist" as someone who's against non-factual objections to factual claims: "you're not an expert", "you're motivated to say this", "you're friends with the wrong people", "your claim has bad consequences" and so on. An intermediate stage would be "grudging rationalist": someone who can refrain from using such objections if asked, but still listens to them, and relapses to using them when among non-rationalists.

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.

... the entire world? As far as I can tell, the vast majority of rationalists would like to have an accurate probabilistic model of the entire world, but are only trying to maintain and update small-ish relevant parts of it. For example, I have (as far as I can recall) never tried to build any model of Congolese politics (until writing this sentence, actually, when I stopped to consider what I do believe about it), nor tried to propagate what I know that relates to Congolese politics (which is non-zero) to other topics.

I feel like this fails to capture some import features of each of these categories as they exist in my mind.

• The rationalist category can reasonably includes people who are not building unified probabilistic models, even if LW-style rationalists are Bayesians, because they apply similarly structured epistemological methods even if their specific methods are different.
• The post-rationalist category can be talked about constructively, although it's a bit hard to do this in a way that satisfies everyone, especially rationalists, because it require giving up commitment to a single ontology as the only right ontology.

I wish I'd remembered to include this in the original post (and it feels wrong to slip it in now), but Scott Aaronson neatly paralleled my distinction between rationalists and post-rationalists when discussing interpretations of quantum mechanics:

But the basic split between Many-Worlds and Copenhagen (or better: between Many-Worlds and “shut-up-and-calculate” / “QM needs no interpretation” / etc.), I regard as coming from two fundamentally different conceptions of what a scientific theory is supposed to do for you.  Is it supposed to posit an objective state for the universe, or be only a tool that you use to organize your experiences?

Scott tries his best to give a not-answer and be done with it, which is in keeping with my categorization of him as a prominent rationalist-adjacent.

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.

What do you mean by "rectified", and are you sure you mean "rectified" rather than, say, "flagged for attention"? (A bounded approximate Bayesian approaches consistency by trying to be accurate, but doesn't try to be consistent. I believe 'immediately update your model somehow when you notice an inconsistency' is a bad policy for a human [and part of a weak-man version of rationalism that harms people who try to follow it], and I don't think this belief is opposed to "rationalism", which should only require not indefinitely tolerating inconsistency.)

I found the framework in the book "Action Inquiry" by Bill Torbert very helpful in this context. In Torbert's framework, a typical young rationalist would be in "expert' mode. There are many good things to be had in later levels.

A brief outline of the framework is here https://www.madstonblack.com.sg/wp-content/uploads/2016/05/Cook-Greuter-maturity-stages.pdf

The post-rationalists, in this view, do not think that rationalism is wrong but that it has limitations. For example a more relaxed attitude to the truth of one's theories can leave you more open to new information and to other ways of seeing things. A recent conversation I had with a young rationalist illustrates this. He criticised me for denying the 'science' showing, in his view, that statins are highly beneficial medications, and felt I was succumbing to woo-woo in being sceptical. I tried to argue that it is not a simple matter of science versus woo-woo. The scientific process is influenced by financial incentives, career incentives, egos, ideologies, the sometimes excessive influence of high-status figures especially in medicine; the ideal of open and complete publication of data and methods and results are by no means met. At the same time one should not assume that with 15 minutes + google you can do better than a highly trained specialist.

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.

This feels excessive to me, but maybe you didn't intend it as strongly as I interpret.

I do think it's the case that if you have incompatible predictions, something is wrong. But I think often the best you can do to correct it is to say something like...

"Okay, this part of my model would predict this thing, and that part would predict that thing, and I don't really know how to reconcile that. I don't know which if either is correct, and until I understand this better I'm going to proceed with caution in this area, and not trust either of those parts of my model too much."

Does that seem like it would satisfy the intent of what you wrote?

This matches my interpretation of the "community". Personally I am more of a post-rationalist type, with the instrumentalist/anti-realist bend philosophically, and think that the concept of "the truth" is the most harmful part of rationality teachings. Replacing "true" with "high predictive accuracy" everywhere in the sequences would be a worthwhile exercise.

I like this, it's simple, it resolved conceptual tensions I had, and I will start using this. (Obvs I should check in in a few months to see if this worked out.)

Thanks, I thought this was useful, especially dividing it into 3 categories instead of two

I strongly disagree with this definition of a rationalist. I think it's way too narrow, and assumes a certain APPROACH to "winning" that is likely incorrect.

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.)

I'm always a bit suspicious of identity or membership labels for humans. There are always overlap, change-over-time, and boundary cases that tend to make me throw up my hands and say "ok, be whatever you want!"

In this post, I'm confused by the phrase "in the sense of this particular community" for a description that does not mention community. The definition seems to be closer to "rationality-seeker" as a personal belief and behavior description than "rationalist" as a member or group actor.

Is there a working definition for anti-rationalist?