The book is great:

"Mr. Dubois," a girl blurted out, "butwhy? Why didn't they spank little kids when they needed it and use a good dose of the strap on any older ones who deserved it — the sort of lesson they wouldn't forget! I mean ones who did things really bad. Why not?" "I don't know," he had answered grimly, "except that the time-tested method of instilling social virtue and respect for law in the minds of the young did not appeal to a pre-scientific pseudo-professional class who called themselves 'social workers' or sometimes 'child psychologists.' It was too simple for them, apparently, since anybody could do it, using only the patience and firmness needed in training a puppy. I have sometimes wondered if they cherished a vested interest in disorder — but that is unlikely; adults almost always act from conscious 'highest motives' no matter what their behavior."

Pretty sure Heinlein predicts the world will go to hell because everyone stopped spanking their kids.