This page credits David Deutsch with first writing about this philosophy of parenting. It's more-or-less the style of parenting I was subjected to. I didn't know until now that he had written about parenting, but he's the author of one of my favorite works of nonfiction, The Beginning of Infinity. I plan to take this approach to parenting with my own children. That is to say, I'm very supportive of it.

HOWEVER: there's a major philosophical failing of TCS, which is that you can't objectively justify claims about what you should and shouldn't do (aka normative claims). If you tell your child "don't hit other kids," they can disagree, which will force you to justify your original statement with a more general normative principle. Eventually you'll be forced to appeal to the foundational principles of morality, something like "it's bad to be in certain mental states like pain, good to be in other states, like joy" and "what matters is which of those mental states the average person on earth is, not which state you, personally, are in." These are one possible version of the sacred principles of morality, and they are probably not justifiable. There are attempts to justify them, such as Sam Harris's The Moral Landscape, but Harris relies (implicitly) on hard to grasp claims like the nonexistence of self, which you're not going to be able to explain to a seven year old unless they're exceptionally introspectively mature.

Sacred principles can just as well be called unquestionable principles. They don't have a justification, but our way of life relies on their acceptance. Society will not tolerate threats to their sanctity, so if you let your child question them, society will punish your child. If you say "don't hit other kids" and your child says (after a chain of justifications) "it doesn't matter if other kids feel pain, what matters is that I feel good when I hurt them," you're not going to be able to rationally argue against that. The most honest response is the ad baculum "if you say things like that when you're an adult, someone might just murder you, so you ought never to do things that you can only justify in that kind of way unless you want to be murdered." But that's not really teaching your child morality; they might someday find themselves in a situation where they don't need to worry about violent reprisal for questioning sacred values, say if they become a powerful dictator. Are you committed enough to morality to want them to be moral even if they don't have to be? Should you be? If yes, then you can't take your children seriously when they question sacred principles. How, then, do you respond when they say "all that matters is that I feel good when I hurt other kids?" You could say "You're wrong. Why? Because I said so." Or you could just punish them. But if they're used to always being taken seriously, they're going to notice that something's fishy.

Fortunately, there's a good chance your child won't ever question sacred principles. I was taken quite seriously as a child, but I justified the sacred principles to myself in ways that only began to crumble when I was 17, so my parents never encountered the dilemma I just described. By the time my old justifications ceased to work I was already adept at being a moral person, and I was ready to understand the lessons of Crime and Punishment, which warns against violating the sacred principles of your society despite acknowledging them to be unfounded, and I was ready to understand the more sophisticated justifications of the sacred principles.

But other children could be more likely to question sacred principles. I wasn't naturally inclined to cruelty. I didn't want to hurt other kids. When I did hurt others, I didn't need to learn why not to, I just needed to learn how not to. Not all kids are like that (not a moral judgment) some will need to by told why they shouldn't be cruel, and you can't do that while taking them entirely seriously.