What is the purpose of public education?

I recently finished reading Neil Postman's "The End of Education" (the title uses the word "end" to mean both "purpose" and "decline"), and I culled some thought-provoking quotations from the book. I will be posting them over the next week.

This first quotation is a fascinating way to consider the end of education.

Our citizens believe in two contradictory reasons for schooling. One is that schools must teach the young to accept the world as it is, with all of their culture's rules, requirements, constraints, and even prejudices. The other is that the young should be taught to be critical thinkers, so that they become men and women of independent mind, distanced from the conventional wisdom of their own time and with strength and skill enough to change what is wrong.

I think that, as an institution, schools are designed to teach the former. However, I think many teachers enter the profession because they believe the latter. Thus begins the tug-of-war between the classroom teacher and administration.

For instance, it is the school's policy that teachers may not show rated R films. On first glance, this sounds reasonable. However, let's say somebody (like me) has a film class full of juniors and seniors, all of whom are 17, and the teacher wants to show The Godfather. You would think that the teacher could show the film. No such luck. "Wait," you say, "what if the students all bring permission slips, signed by their parents?" Nope, no rated R films...ever----school policy.