The age of franchise was lowered to 18 because 18-year-olds can be drafted. When the lowering happened, in ’71, 18-year-olds were being drafted and sent to Vietnam. It seemed fair to let people fighting a war help choose the people running the war. Though of course you could argue that people reach physical maturity before mental maturity, which is why you don’t get a driver’s license when you hit puberty.

But anyway: At the moment, in the United States, the legal view is that if you’re old enough to fight, you’re old enough to vote — but you’re not old enough to buy liquor. The drinking age is 21. Why can’t someone buy liquor till he’s 21? Because, say the lawmakers, at 18, you’re not old enough to make mature decisions about issues as weighty as alcohol.

It’s true, the weightiest issue on the minds of 18-, 19-, and 20-year-olds (by and large) is how to get alcohol. They may not know when the market crashed, but they certainly know which bars will serve them and which delis will sell them beer. (I know what I’m talking about; four years ago I was 20.) So, I propose a trade. Raise the voting age to 21 and lower the drinking age to 18, all in one tidy amendment. Surviving three years of being able to drink legally is a good test of fitness to vote, anyway, and maybe this deal could get a little momentum.