I would ask what did they mean by "working"? If the kid doesn't understand addition anyway, and asks what is 2+2, why not tell them 4? What would be the rationale to say it's 5, what is "working" here? It answered the question, but so would the correct answer.

Then you might realize that, yes, not knowing anything about parenting actually does mean you have no basis to evaluate parenting decisions.

If that parenting knowledge gives people expert insight, why don't they share it? Why hide behind "only parents would understand" (even ignoring that some parents disagree with them)? Why not refute the so obviously wrong armchair amateur advice with the correct facts? I see lots of talk, where is the money?

not knowing anything about parenting actually does mean you have no basis to evaluate parenting decisions.

It's cute, but sadly I saw what you did there: What or who, other than asexually reproducing life forms, or maybe those that lay eggs, does not know anything about parenting?

There is an scientific approach to parenting. We can take a testable metric like body weight, and apply rigorous analysis of contributing factors, like eating habits and exercise, and arrive at a more-or-less objective conclusion like, "Feeding kids lots of sugar will make them fat." That's not a conclusion that's amenable to subjective analysis, and non-parents are as capable of drawing them as parents are (and in fact, non-parents may be better, because...)

There is also an intuitive approach to parenting, which is how most parenting decisions actually get made, because once you get the little details of keeping your kid alive and healthy taken care of, you start running into abstract problems like, "I want my child to have a happy and fulfilled life," for which really actionable scientific evidence is thin on the ground. Parents develop this intuition over the course of years of near-constant exposure to their children, where every single little thing they do has some consequence which they have nowhere near enough time or energy to seriously consider. It's the sort of problem our brains are made to solve, and generally it works out okay.

Consider that if you aren't a parent or full-time-plus childcare professional, you have something like one one thousandth that level of interaction with children, and much less in a custodial role. So let's swap out some nouns and see if this makes sense to you:

There's a question about a programming language. In the discussion are a layman, who has never used the language, and an amateur, with fifty thousand hours of subject matter experience. Somewhere are educated people studying the language rationally, but they are not here.

The amateur says, "Look, I know you have your own opinion and all, but I don't think you're really even qualified to discuss this if you haven't done any programming before."

The layman says, "Why not? This stuff is just common sense."

The amateur replies, "I understand it looks like common sense to you, but, in the nicest way possible, you just don't know anything about this."

The layman protests, "Of course I know about it! I use computers almost every day, and so does everyone here."

The amateur is frustrated. "That's... not really the same thing as programming at all."

The layman feels challenged. "Okay, if you're the big expert here, why don't you just share some of this so-called expertise with the rest of us?"

The amateur is perplexed. "...that's what I'm doing."

This discussion will never arrive at a productive result. There is just no path from here to there.

Look, I know you have your own opinion and all, but I don't think you're really even qualified to discuss this if you haven't done any programming before.

Yeah, but if the programmer actually does have the experience, he CAN prove it, albeit in language the layman may not understand or follow. I don't see this happening here in this particular case. And therefore...

The layman feels challenged. "Okay, if you're the big expert here, why don't you just share some of this so-called expertise with the rest of us?"

The amateur is perplexed. "...that's what I'm doing."

This discussion will never arrive at a productive result.

Where are you guys doing that, sharing the expert knowledge? You skip INSTANTLY to "only parents would understand", AND you ignore the facts that some parents disagree, which is rendering your entire argument zilch -- that isn't hard to get, I already mentioned that and am now repeating; will you repeat with an even bigger wall of text every time I point out that flaw? Are you treating me like a kid, perhaps? No need to explain, just keep using big words and bloat it up? Pah.

Maybe I should make it explicit that I'm not a parent; I've just heard enough experts say that to believe it. I am flattered you think I talk like a grown up, though.

The fact that your intuition is deceiving you is expert knowledge.

Nah, it's gotta have slightly more substance than that; no matter how often you repeat it. Just literally telling me to shut up won't cut it either.

Riddle me this, how is it not possible to tell your kid you want them to be not yell so loud when playing computer games impossible, and in what situation is it preferably to deceive them? If they actually respect their toys more than their parents, that's clearly a FUBAR situation.

You might say you don't know, because you are not familiar with the details. Well then, what of the stuff you do have experience with would lead you to say "hands off, it's 'their' children"? I mean, by this logic you also give carte blanche to any and all abuse, too: after all, nobody should judge what people do with 'their' children. I say bollocks to that, and am still waiting for a single argument that actually applies to this situation, instead of just hiding behind generalities, strawmen and logical fallacies.

Oh, it's possible. Nobody claimed it's impossible. The question is, what do you do when (not if, when) it doesn't work? And by "doesn't work", I mean that they stop yelling for 30-90 seconds and then they start again.

and in what situation is it preferably to deceive them?

What people have been telling you over and over is that these decisions aren't as clear cut as

  if A and B and C then deception.preferable = true

If they actually respect their toys more than their parents, that's clearly a FUBAR situation.

That statement reveals a profound lack of understanding of the subject matter, which is why so many people are criticizing you.

I say bollocks to that, and am still waiting for a single argument that actually applies to this situation, instead of just hiding behind generalities, strawmen and logical fallacies.

Which just goes to show you haven't actually bothered to look for those arguments. If you had, you would have found an explanation I offered, based on my experiences with my son, on observing other kids and on talking to other parents and educators: http://news.ycombinator.com/item?id=5155974

Feel free to disagree with the explanation, but please stop throwing hissy fits because people called you out on your lack of credibility.

No, it means I got a LOT of replies goin on and on about strawmen. I consider those replies to my posts, imagine that.

please stop throwing hissy fits because people called you out on your lack of credibility.

Well, I appreciate the irony and the projection. Mocking non-sequitur arguments repeating what they missed isn't throwing a hissy fit just because I'm not going out of my way to read the whole thread over and over, and your argument boils down to "believing in Santa doesn't hurt anyone either". Well, that still makes it an undesirable, unnecessary, mediocre thing at best. And I don't buy the whole "kids at 4 are super egotistical" either, some are rather protective of their baby sibling for example, so they clearly know what being disturbed is. Actually, I remember one thing my father told my when I was a kid, that you can't lie to babies, they always notice... I took that literally, and told my baby brother I'd go to the toilet, thinking "I will go to the kitchen instead". When I left the room and he failed to cry, I was disappointed, I was already planning on using him as lie detector. You see, the fact that you shrug off the myth of Santa, the uttering of which would have been like crapping on the carpet for my family, just tells me we experienced and live in different worlds. And I couldn't care less about the additional credibility which the "parent" flag would give me, it's just not relevant; if I have kids they might turn out to be completely different persons who I was. But instead of speculating about a kid who is not me, even if it's "mine", I actually do remember. As you say so ironically, "Feel free to disagree", feel free to claim I remember wrong or whatever; but don't throw hissy fits just because your kids don't notice that shit.