Why is philosophy not taught in high school?

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Why is philosophy not taught in high school? I have heard some arguments against it, but they all seem pretty poor such as: "parents would not like their children questioning their views". It seems like philosophy has a lot to give in a high school setting, at the very least classes like Critical Thinking would give students tools for assessing arguments. I could understand if most people went on to college, but many don't and it seems like some of the skills which philosophy bestows could greatly benefit our society. I really don't see why professional philosophy has not ventured down this route. I would be very thankful for any insight on this topic. Thanks, William P.