Lobsang1979: Why would we have to teach university level Philosophy at high school? Knowledge is a progressive thing that is gathered over the course of a lifetime. Pupils do not learn all there is to know about quantum mechanics or electromagnetic forces when they are 11 years old, but instead learn the basics of physics upon which to build an understanding of the world we live in.
I do not think that a pupil should be fluent in the philosophical schools upon graduating high school, but a grasp of philosophical debate and though processes would be just as beneficial as the ability to use correct grammar or demonstrate ability in public speaking. The current education system in the UK drives kids to be scientifically successful, because that is what is good for our economy supposedly. Yet many school-leavers I meet here are extremely immature when it comes their moral or dare I say, even, spiritual aspects. There is more to life, in my view, than converting knowledge into money or success.
I certainly agree with your premise that the more an individual knows, the greater the temptation to show arrogance with that knowledge. I was far more arrogant as a 20 year old than I am now as a 30 year old, for example. However, the idea that adults are less likely to formulate half-baked ideas than young people are makes me smile. Some of the most shockingly stupid ideologies of the modern world have been formed by well-educated, yet philosophically neutered, individuals.
By the way, when I say 'Philosophy', I do not necessarily mean the Classics or the various schools. I mean "the study of general and fundamental problems concerning matters such as existence, knowledge, values, reason, mind, and language".
Oh, I fully agree that adults can be just as prone to thinking they can fix the world with half-baked ideas as children.
And you think people need more morality and the like: Guess what, these guys agree with you :p. Hell, I technically agree as well. Guess what the purpose of wanting to teach religion in school is? Teaching morality.
If all you mean is "learning how to learn", then that IS school. I know in the US, teachers teach for tests, not education. And I suspect that is similar around the world (easiest way to measure the competency of a school is standardized testing...). And there is no way to fix that without opening another can of worms.
But either way, that knowledge is not exclusive to philosophy. You can learn that from anything. Teach a kid how to figure out the patterns of the multiplication table. Teach a kid how to apply their knowledge of math to their knowledge of physics (and vice versa). Teach a kid how to notice the similarities between historical events. You don't need a specific class for that, just better teachers.