Saith Robin in "Seeking a Cynic's Library":
Books on education, medicine, government, charity, religion, technology, travel, relationships, etc. mostly present relatively idealistic views, though of course no view is entirely one way or the other. So one reason the young tend to be idealistic is that most reading material they can easily find and understand is idealistic.
My impression of this differs somewhat from Robin's (what a surprise).
I think that what we see in most books of the class Robin describes, are official views. These official views may leave out many unpleasant elements of the story. But because officialism also tries to signal authority and maturity, it's hardly likely to permit itself any real hope or enthusiasm. Perhaps an obligatory if formal nod in the direction of some popular good cause, because this is expected of officialdom. But this is hardly an idealistic voice.
What does a full-blown nonfictional idealism look like? Some examples that I remember from my own youth:
- Jerry Pournelle's A Step Farther Out, an idealistic view of space travel and more general technological advancement, and the possibility of rising standards of living as opposed to Ehrlichian gloomsaying.
- Brown, Keating, Mellinger, Post, Smith, and Tudor's The Incredible Bread Machine, my childhood introduction to traditional capitalist values.
- Eric Drexler's Engines of Creation (and to a lesser extent Ed Regis's Great Mambo Chicken), my introduction to transhumanism.
- Richard Feynman's Surely You're Joking, Mr. Feynman (for traditional rationalist values).
Supposing you wanted your child to grow up an idealist - what nonfiction books like these could you find to give them? I don't find it easy to think of many - most nonfiction books are not like this.
On the other hand, I suspect that idealistic fiction aimed specifically at children is a far greater cultural force than anything they pick up from their school textbooks. Textbooks are marketed to adult textbook-selectors; juvenile fiction and children's television are actually aimed at children.
Of course this just implies a chicken-and-egg problem; why do children enjoy idealism more than cynicism? On this score I would suggest that children in the hunter-gatherer EEA have no chance of successful rebellion, and so haven't yet developed certain emotions that will come into play after puberty. But children will be actively engaged in absorbing tribal mores during their maturation, and may benefit from signaling such absorption.
Teenagers who act as if they could still get together with their friends and split off to form their own tribe, enjoy cynicism aimed at current authority figures and idealism aimed at their new tribe.
When such forces have petered out, I suggest we are left with a mostly socially-determined adult equilibrium: idealism about some distant subjects is used to signal virtue, cynicism about other distant subjects is used to signal sophistication.