C.S. Lewis wrote a short book attacking moral subjectivism in education; it's available online here as a pdf, here as raw text, and here as a series of videos [1 2 3], and I think probably worth reading in full (at 50 pages or ~100 minutes of video at 1x speed). This post is mostly me rambling about what I saw as the central point, especially connected to individual development and community health, by quoting sections and then reacting to them.
The book begins with a reaction to a grammar textbook (written in 1939) euphemistically called The Green Book whose lessons are also philosophical; Lewis doesn't object to the bait-and-switch (outside of one paragraph) so much as the content and quality of the philosophy. (One suspects Lewis wouldn't object to the Copybook Headings referenced by Kipling, even tho that mixes writing lessons and philosophy.)
Until quite modern times all teachers and even all men believed the universe to be such that certain emotional reactions on our part could be either congruous or incongruous to it--believed, in fact, that objects did not merely receive, but could merit, our approval or disapproval, our reverence or our contempt.
First, let's get the obvious objections out of the way: the claim of universality is probably false. Even supposing it were true, then the underlying change seems worth investigating. Naive belief that one's map is objective reality disintegrates on contact with different maps and after noticing surprising divergences between one's predictions and observations; one can imagine this happening in the moral realm as well as the physical one. But presumably we should just ignore this as standard "the contemporary world is fallen and bad" framing instead of an actual historical claim.
The more interesting claim here is the question of whether or not there can or should be a question of merit, distinct from a question of flavor or fact. A previous taxonomy I've liked a lot (that I was mostly introduced to by Sapiens) is the split between objective (determined by reality), subjective (determined by the person in question), and intersubjective (determined by some group process); the rules of a game are not just 'my personal whims' and are also not 'scientific' in the sense that any outside observer would be able to determine it themselves. Without access to human civilization; aliens would figure out the same physics, and they might play something like chess, but they likely won't play chess. Nevertheless, concepts like chess are an important component of your epistemology and there is such a thing as a 'legal move' or 'illegal move.'
But what is common to [religious traditions] is something we cannot neglect. It is the doctrine of objective value, the belief that certain attitudes are really true, and other really false, to the kind of thing the universe is and the kind of things we are. Those who know the Tao can hold that to call children delightful or old men venerable is not simply to record a psychological fact about our own parental or filial emotions at the moment, but to recognize a quality which demands a certain response from us whether we make it or not.”
Lewis is trying to go a step further; in my framing, there's a thing about the 'game that is society' that involves 'playing with reality' in a way that makes it something a little more objective than the 'intersubjective.' It's not just that everyone jointly decided that old people are venerable and thus the fashion is to venerate them; it's that somehow venerating old people is congruous with the Tao and not venerating them isn't, and so getting that question wrong is worse on some dimension than just playing chess by the wrong rules. Play chess by the wrong rules and people will throw you out of the chess club; play society by the wrong rules and your society collapses or misery abounds. Lewis uses 'the Tao' to refer to both 'the underlying territory as distinct from the map' and 'the sort of human behavior congruous with the territory', in a way that seems connected to this sense of 'the universe as participant in the game that is society.'
Note that he says "true to the kind of thing the universe is and the kind of things we are", as opposed to simply "true." This seems consistent with 'morality as the product of game theory', and a sort of subjectivism that allows for different environments to have different moralities, or different professions to have different ethics; the Tao of the soldier may be distinct from the Tao of the doctor, and the Tao of the Inuit different from the Tao of the Swahili. It reminds me of the claim that Probability is Subjectively Objective; if one is a soldier, the 'right way to be' is different than if one is a doctor, but there is still a meaningful sense in which there is only 'one right way to be' that is not destroyed by that variation. [Imagine a function from 'broad situation' to 'proper behavior'; this function can vary as you change the input while still being a deterministic function.]
If they embark on this course the difference between the old and the new education will be an important one. Where the old initiated, the new merely ‘conditions’. The old dealt with its pupils as grown birds deal with young birds when they teach them to fly; the new deals with them more as the poultry-keeper deals with young birds--making them thus or thus for purposes of which the birds know nothing. In a word, the old was a kind of propagation--men transmitting manhood to men; the new is merely propaganda.
The contrast between 'initiation' and 'conditioning' stuck out to me. One way you could get such a split is a separation between Educators and Students where most students will not become educators, whereas most boy-children become men. When I try to figure out what the difference between religions and cults are, especially when it comes to things like the rationality community, I keep thinking about this sense of "explorers trying to create more explorers", and how it differs from "carnies trying to use marks", and somehow it seems connected to feedback loops. The man trying to make the next generation into men relates to the next generation differently from how the carnie trying to extract money from marks relates to those marks. Not only does the former involve identification with the audience (where the latter recoils from that), the former is trying to get the audience to understand the whole process (so that they too, in their time, can perform it), whereas the latter is trying to get the audience to misunderstand the whole process (so that they will come back and be fleeced again).
To the extent that the High Modernist or Reformer or Rationalist sees the outside as a thing to be optimized, as opposed to part of a system that needs to support further optimization, it seems like there's some deep short-sightedness and disconnection from the Tao. To the extent that some profession sees the outside world as something to be profited from, as opposed to a body in which they are an organ, we should expect the society to be sick in some way.
Let us suppose for a moment that the harder virtues could really be theoretically justified with no appeal to objective value. It still remains true that no justification of virtue will enable a man to be virtuous. Without the aid of trained emotions the intellect is powerless against the animal organism. … The head rules the belly through the chest--the seat, as Alanus tells us, of Magnanimity, of emotions organized by trained habit into stable sentiments. The Chest-Magnanimity-Sentiment--these are the indispensable liaison officers between cerebral man and visceral man. It may even be said that it is by this middle element that man is man; for by his intellect he is a mere spirit and by his appetite mere animal.
The operation of The Green Book and its kind is to produce what may be called Men without Chests. It is an outrage that they should be commonly spoken of as Intellectuals. This gives them the chance to say that he who attacks them attacks Intelligence.
This reminded me of Bayesians vs. Barbarians, with a new dimension added; it is not that the Barbarians gain from having less in their head, it is that the Bayesians lost because they forgot to develop their chests. When I was younger, I read through The Fountainhead and Atlas Shrugged and was confused by the educational strategy; here were these staunchly moral characters, as evidenced by their disgust at taking immoral actions that would benefit them, but the source of their morality seemed unspoken and unjustified. This felt like a serious contrast to what I observed at my local church, where people put in serious amounts of effort to become slightly more aligned with their reasoned values. It looked like all that was assumed unnecessary; one simply had to paint the picture of correctness and it would be followed by the righteous without any exercise or training.
Another Eliezer reference is Feeling Rational, which points at the congruity property of emotions, but only with regards to factual truth; if you're afraid about an iron being hot and it's cold, you're making a mistake, and if you're calm about an iron being cold and it's hot, you're making a mistake. But that seems to miss the intersubjective angle; in some contexts, reacting to criticism with defensiveness is inappropriate and reacting to criticism with curiosity is appropriate, and some large part of 'training human rationality' is inculcating the right emotional responses in oneself. A dojo isn't just about transfer of technique, but also about transfer of attitude.