A friend sends along an email attachment—a handwritten letter by his 8-year-old son, Peter. It’s addressed to First Lady Michelle Obama. “It all started because he saw something about school lunches [and] how ketchup is bad for you, and that Michelle Obama wants to limit the amount of ketchup” in schools, my friend explained. When the boy’s mother reminded him he attends a private school, making the ketchup rationing a nonissue, “He said something about wanting to ‘give a voice to the voiceless.’” But ketchup is actually the least of the boy’s concerns, as he then continues onto foreign policy,...