Susan Neiman describes idealism for adults.

Question: Is it always good to be an idealist?

Neiman:  I think it’s always good to be a grown-up idealist, which is--  The whole subtitle of the  book is Grown-Up Idealist. A grown-up idealist is someone who recognizes the equal importance of things as they are and things as they should be. This is a distinction that goes back in particular in all its clarity to Immanuel Kant who said, “This is the distinction.” I think the big metaphysical problem--  I’m not sure that--  And I’m loath to talk about one big problem but the central problem connecting both metaphysics and morality is the difference between things as they are and things as they should be, and most people tend to err on one side or the other. Most people tend either to look at things as they should be and talk themselves in to the idea that things really perhaps are as they should be without looking at the facts on the ground. You can also err in the other direction and use the word “realistic” to mean just taking things as they happen to be right now. Think about what you mean when you tell somebody to be realistic. What you’re really saying is, “Decrease your expectations. Things aren’t going to get much better. They’ll probably get worse and you’ve got all your psychological bases covered if you assume actually the worst.”  So that’s a form of realism that says, “Well, the way that things are now is the only thing that’s real and it’s the only thing we should pay attention to.”  A grown-up idealist pays attention to both. He says, “I absolutely can look at things as they are in the face while still guiding my actions by ideals of things as they should be.”