Raise age to serve, vote, buy guns

So just how old is old enough to know better, and just how young is too young to care?
Those are the questions up for debate as some lawmakers in Washington and Florida look to increase the age at which Americans can buy semi-automatic rifles to 21. It’s a question on which the nation has gone back and forth over the years for all kinds of liberties, from voting to drinking to smoking to guns.
Is an 18-year-old a full citizen of the United States? Does the equal protection clause in the Constitution allow us to bar one group of full citizens from a liberty others enjoy? Is it reasonable to say an 18-year-old is mature enough to vote and to decide to serve in the military but not mature enough to buy a beer, or a smoke or a semi-automatic hunting rifle?

Source: newsday