A lot of kids are smarter than some adults. The system already lets people vote who're drug addicts, have cognitive disorders, or are uncaught criminals. The system already relies on a bandwagon logical fallacy to decide our futures, so things would probably only improve if kids were allowed to vote.
Children bring several things to the voting booth that adults do not. Children have a unique set of concerns and an inherent sense of optimism. This would be good, not bad for our voting system. Others claim that children are too easily manipulated, but they clearly haven't worked much with teenagers. The things that children care about aren't at all different than the things that adults care about. In my experience the cares of children tend to fall in one of two camps: either they have experienced hardship and they care about others in the same situation, or they haven't experienced much hardship and they latch onto broader, worldly concerns. They are persuaded by the things that they care about, but they will turn contrarian in a heartbeat if something stands in the way of their beliefs. This is an enthusiasm and independent spirit that we should embrace and emulate rather than dismiss.
More than the fact that children as young as 12, perhaps younger, are more thoughtful and independent than they are typically given credit for, the result would be a more engaged public generally. As a teacher this is so incredibly apparent to me. Students start checking out of academic pursuits slowly one after the other. They are incredible learners, but stop applying the learning to schooling at some point in middle school, give or take. Sometimes this is because they have difficult circumstances to deal with, other times it is because they feel they have a lot to offer and we're not showing them the respect of letting them really contribute to anything. Voting rights would engage students because they would have a public stake. This is more than we can say for giving adults voting rights. Voting rights are like paper currency, they have value only if we collectively believe they have value. As soon as we stop believing that our vote counts, our vote won't. American adults in particular fall into this trap, but students would not. Again, their optimism would give us something to emulate and be inspired by.
Kids are very gullible and tend to believe most things people say without taking a deep thought or looking around to find hard cold facts about what something is really about. Yes debatable things are hard to put hard cold facts to without the opposition making good points that's what makes something debatable but yet at the same time kids should not be voting mostly because they do not understand half of what they hear or see. Perhaps teenagers do but smaller children perhaps not. When I was a little kid, I knew the three branches of government and what they do but otherwise I didn't know anything about the parties or what I believed in. Perhaps if people went into context with little kids about what party believes in what and why then perhaps but even then kids are immature and tend to not care about such issues
The thing that worries me about such a proposition is that it doesn't take into account the seriousness of voting, and how it can have direct implications on the lives of many - for better or worse.
Children, no matter how informed they may be, are generally ignorant of the reality of the world which surrounds them. It's very easy to vote for utopian concepts (whether left or right) when you're not the one who's either paying taxes or dealing with the consequences of the government's actions.
Also, I'd point out that children are still going through a serious stage of sociological development, and their views shall neither be fully formed or thought out - nor would you expect them to be. And if they elect a particular individual who was incredibly damaging to society at large, it's scary to imagine the severe level of emotional trauma it could place upon adolescents.
Those are but a few of the reasons I'd decry such an idea. Getting youngsters involved in free-thought and discussion is a healthy and wonderful thing, but granting them to vote is a socially irresponsible act which undermines the seriousness of democracy, and places cruel pressures upon any child.
Allowing children to vote is the dumbest idea possible. Children are way too easily manipulated and not educated enough. Their brains are not fully formed and they have no concept or grasp of many things that are important to people in this country that only apply to adults. As well, they would vote for whoever their parents would tell them to vote for.
Kids shouldn't be allowed to vote because their minds are too easy to manipulate. If you promise a kid candy for voting for a specific candidate then they will vote for that candidate just to get a piece of candy. Plus depending on what age they are they have not come to terms with the harsh reality we face and still are in their "perfect wonderland" of fantasy and rainbows.