The Rationalists of the 1950s (and before) also called themselves “Rationalists”

the “critical rationalists” (who are a contemporary movement that involves David Deutsch, the “taking children seriously” people, and some larger set of folks who try to practice a certain set of motions and are based out of the UK, I think)?

Critical rationalism is basically the scientific philosophy of Karl R. Popper. An Austrian, he relocated to the UK in the 30s for similar reasons to Sigmund Freud's. So CR ended as being a kind of UK thing, despite having its roots in the Vienna Circle. (It also has a following in Oz and NZ, but not so much in the states).

It's not particularly contemporary, therefore...more of a version 2.0 of logical positivism. I don't know of any specific connection between mid 20th century UK atheism/humanism and CR...but it would be strange if there were none.

There were a lot of developments in philosophy-of-science post WWII -- Kuhn, Feyerabend , etc -- and CR somewhat faded from fashion until Deutsch revived it with his popular work in the 1990s. (Although Popper's falsificational criterion for science remains popular among working scientists).

Deutsch's (and other subsequent) versions of CR got entangled with Austrian economic, libertarianism ,and various other minority beliefs.

I think the link in your comment points to something that seems like a one-man show. The man's name is Elliot Temple.

He has a picture on his homepage about the philosophical traditions he builds on, and apparently he makes some money selling his wisdom, but is he actually a part of some larger debate? I mean, other than the forum he owns and writes most of the comments on, with only two or three other active participants.

By the way, he was posting on LW [LW · GW], and got banned. He accuses David Deutch of organizing harassment against him, and generally seems obsessed about him. Generally, he seems... well, crazy... in a way that is not immediately obvious, but once you start talking to him and get his attention, you are probably going to regret it, because he just can't stop. He will write a ton of text, a separate essay analyzing the meaning and logical flaws of every single sentence you wrote, then he will accuse you of being irrational, and then he will accuse you of being irrational for not responding to him in the same way, and then he will keep writing articles on his blog about how irrational and cowardly you are for avoiding him.

This distinction was always fake. The Wikipedia page on Rationalism begins with portraits of Descartes, Spinoza, and Leibniz. Spinoza was a lens grinder who worked closely with astronomer-physicist Christiaan Huygens and wrote in his magnum opus, Ethics, that we only know about things in the world through our bodies interacting with them. It is unclear to me how it is possible for someone to be more committed to looking at the world.  The Wikipedia page on Empiricism begins with portraits of Francis Bacon, John Locke, and David Hume. Hume's An Enquiry Concerning Human Understanding includes the following, which implies that abstract mathematical reasoning is one of the two valid sources of knowledge, and refers to experimental reasoning:

If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion.

No, 'rational' here is being used in opposition to 'irrational', 'religious', 'superstitious', etc., not in opposition to 'empirical'.

Quoting Wikipedia:

In politics, rationalism, since the Enlightenment, historically emphasized a "politics of reason" centered upon rational choice, deontology, utilitarianism, secularism, and irreligion^[23] – the latter aspect's antitheism was later softened by the adoption of pluralistic reasoning methods practicable regardless of religious or irreligious ideology.^[24][25] In this regard, the philosopher John Cottingham^[26] noted how rationalism, a methodology, became socially conflated with atheism, a worldview:

"In the past, particularly in the 17th and 18th centuries, the term 'rationalist' was often used to refer to free thinkers of an anti-clerical and anti-religious outlook, and for a time the word acquired a distinctly pejorative force (thus in 1670 Sanderson spoke disparagingly of 'a mere rationalist, that is to say in plain English an atheist of the late edition...'). The use of the label 'rationalist' to characterize a world outlook which has no place for the supernatural is becoming less popular today; terms like 'humanist' or 'materialist' seem largely to have taken its place. But the old usage still survives."

The Online Etymology Dictionary says:

1620s, "one who follows reason and not authority in thought or speculation," especially "physician whose treatment is based on reasoning," from rational + -ist. In theology/philosophy, "one who applies rational criticism to the claims of supernatural authority or revelation," 1640s. This sense shades into that of "one who believes that human reason, properly employed, renders religion superfluous." Related: Rationalistic; rationalism (1800 in medicine; 1827 in theology, "adherence to the supremacy of reason in matters of belief or conduct;" by 1876 in general use).

Separately, your definitions for rationalist vs. empiricist are off. Per SEP, the usual definition is some variant of 'rationalists think we have some innate knowledge, while empiricists think we get all our knowledge from experience'.

Alberto Vanzo argues that the modern philosophical 'rationalist vs. empiricist' dichotomy comes from Kant and early Kant-influenced thinkers. Though the dichotomies 'rational vs. irrational' and 'reason vs. experience' are both much older than the term 'rationalist'; e.g., Francis Bacon in ~1600 was contrasting 'rationalis' with 'empiricus', though this was talking about dogmatists vs. experimentalists, not talking about the modern (Kant-inspired) rationalist v. empiricist dichotomy.

If I try to steelman the Rationalist-Empiricist divide:

Empiricists think that arguments justifying organized violence are nonsense so we ought to ignore them, do what we like instead, and argue about math and science.

Rationalists think that arguments justifying organized violence are sketchy so we should investigate them carefully as hypotheses for how mind organizes itself in the world.

Basically you do long division by every prime less than 100. 

Yeah. The communist associations of past iterations of "rationalist" schools or communities is one the biggest piles of skulls I know about and try to always keep in mind.

Wikipedia uses this URL about Stalin, Wells, Shaw, and the holodomor as a citation to argue that, in fact, many of them were either duped fools or worse into denying the holodomor. Quoting from the source there:

Shaw had met Stalin in the Kremlin on 29 July 1931, and the Soviet leader had facilitated his tour of Russia in which he was able to observe, at least to his own satisfaction, that the statements being circulated about the famine in the Ukraine were merely rumours. He had seen that the peasants had plenty of food. In fact the famine had notoriously been caused by Stalin in his desperation to achieve the goals of his five-year plan. An estimated ten million people, mostly Ukrainians, died of starvation.

As someone who flirts with identifying as part of some kind of "rationalist" community, I find the actions of Shaw to be complicatedly troubling, and to disrupt "easy clean identification".

Either I feel I must disavow Shaw, people like Shaw, and their gross and terrible political errors that related to some of the biggest issues and tragedies of their era, or else I must say that Shaw is still a sort of somehow a tolerably acceptable human to imagine collaborating with in limited ways [LW · GW] in spite of his manifest flaws. 

(From within judeo-christian philosophic frames this doesn't seem super hard. The story is simply that all humans are quite bad by default, and it is rare and lucky for us to rise above our normal brokenness, and so any big non-monstrous actions a human performs is nearly pure bonus, and worthy of at least some praise no matter what other bad things are co-occuring in the soul of any given person.)

Shaw's kind of error also troubles me when I imagine that there might be some deep substructure to reasoning and philosophy such that he and I share a philosophy somehow, and he did that while having a philosophy like mine... then if "beliefs cause behavior" (rather than mostly just being confabulated rationalizations after behaviors have already occured) then I find myself somewhat worried about the foundations of my own philosophy, and what horrible things it might cause me to "accidentally" endorse or promote through my own actions.

Maybe there is some way to use Shaw's failure as a test case, and somehow trace the causality of his thinking to his bad actions, and then find any analogous flaws in myself and perform cautious self modification until analogous flaws are unlikely to exist?  But that seems like a BIG project. I'm not sure my life is long enough to learn all the necessary facts and reasoning carefully enough to carry a project like that to adequate completion.

Thus the practical upshot, for me, is to be open to "fearing to tread" even more than normal until or unless there are pretty subjectively clear reasons to advance.

Also, my acknowledged limitations lead me to feel a minor duty to sometimes point out obviously evil things that my mental stance can't help but see as pretty darn evil? Not all of them. Just really really big and important and obvious ones.

My current working test case for this is the FDA, which I suspect should be legislatively gutted. 

Maybe I'm wrong? Maybe in saying "FDA delenda est" semi-regularly I'm making a "Shaw and the Holodomor level error" by doing the opposite of what is good? 

It seems virtuous, then, to at least emit such an idea every so often, when I actually really can't help but believe in and directly see a certain evil, and see if anyone can offer coherent disagreement or agreement and thereby either (1) help fix the world by reducing that particular evil or else (2) help me get a better calibrated moral compass.  Either way it seems like it would be good?

Also, in general, I feel that it is a good practice to, minimally, acknowledge the skulls so that I know that "ideas and identities and tendencies similar to mine" might have, in the past, lead to bad places.

To hide or flinch from the fact that former-"people calling themselves rationalists" were sometimes pretty bad at the biggest questions of suffering and happiness, or good and evil, seems like... like... probably not what someone who was good at virtue epistemology would do?  So, I probably shouldn't flinch. Probably.

At the beginning, LessWrong was strongly atheistic:

• Religion's Claim to be Non-Disprovable [LW · GW]
• Avoiding Your Belief's Real Weak Points [LW · GW]
• Beyond the Reach of God [LW · GW]
• Atheism = Untheism + Antitheism [LW · GW]
• Is Humanism a Religion-Substitute? [LW · GW]
• Belief in Belief [LW · GW]
• Professing and Cheering [LW · GW]
• An Alien God [LW · GW]
• The Sacred Mundane [LW · GW]
• Let Them Debate College Students [LW · GW]
• A Parable on Obsolete Ideologies [LW · GW] -- goes full Godwin on religion
• Theism, Wednesday, and Not Being Adopted [LW · GW]
• How Theism Works [LW · GW]
• My Atheism Story [LW · GW]

Later, writing about religion felt like beating a dead horse.

Then, I suppose as a part of the "meta-rationality" wave, the idea of cultural evolution became popular: how people can do the right things for wrong reasons (and premature rationality can hurt you), for example how divination is useful, not because supernatural things are actually true, but because divination is effectively a source of randomness, so it is useful where a random-number generator would be useful, e.g. when fighting an intelligent adversary or hunting animals. This made religion somewhat acceptable -- perhaps not epistemically, but instrumentally.

We also had the period when LessWrong was effectively dead and replaced by Slate Star Codex as a center of rationalist discource, but SSC was not explicitly atheist, and at least half of its comment section did not even aspire to be rationalist.

Lately Buddhism became popular on LessWrong -- a fact that I hate, and I have already complained about it many times -- first it started as "there seems to be some scientific evidence in favor of meditation giving its users some benefits" which is okay if true, but of course the entire expert literature on this topic is full of memetic hazards, and we gradually move towards accepting parts of Buddhist epistemology, or at least privileging them as hypotheses. (Sometimes I imagine a parallel universe where e.g. Catholics have invented push-ups, and the rationalists in that universe progress from "hey, there is a scientific evidence that push-ups are good for your body" towards accepting the wisdom of Catholicism and praying to Lord Jesus.) I sincerely hope that this all is just temporary and we will grow out of it, better sooner than later.

(And I suspect the recent silence on the topic also reflects the recent changes in American politics. To put it bluntly, a decade or more ago, it was like "religion = Republicans = the bad guys", but then people realized that Islam is a religion too, and being a too consistent atheist also makes you "islamophobic", which is a politically incorrect thing, and therefore it is better to just avoid this topic.)

Yes, I said "overlap" not "coincide" for that reason. The present movement has more discussion of applied epistemology, ideology, and world-view formation, and less discussion specifically focused on religion. My sense is that the earlier movement is also more focused on Christianity than on religion or ideology in general. 

Evolution was a pretty new theory in 1880 and so it makes sense it would be discussed more. (AI is a big topic for the present movement and not for the earlier). 

I can only agree , since I've been saying for a long time that the current rationalist movement is only the latest iteration of many.

I'd agree with that, except for the word "only". It is no criticism of the present, to observe that it has a history.