In the United States, you’re an adult once you turn 18. You’re old enough to drive, old enough to get married, old enough to raise children, old enough to vote, old enough to sign an apartment lease, old enough to open a credit card, old enough to buy a gun, old enough to watch porn and old enough to serve in the military and die for your country.

If you are 18, however, you are not old enough to smoke (marijuana or otherwise now). You’re not old enough to drink. You’re not old enough to gamble. You’re not old enough to run a brothel in Lyon County even though you’re old enough to work in a brothel as a prostitute there. You’re old enough to work as a prostitute in Nye County. You’re also not old enough to get naked in front of a paying audience in Reno, but nobody will stop if you get naked in front of a paying audience in Clark County as long as you have a work card.

On the one hand, I can’t think of a more important lesson for new adults to learn than that the rules enforced upon us by our local, state, and federal governments are contradictory and capricious. On the other hand, maybe we’re teaching the lesson a bit too well.

Speaking as a parent, I understand that not every 18-year-old is magically equipped with the discernment and maturity necessary to navigate the entirety of the adult world without issue. Speaking as a former college student, I also understand that not every 21-year-old is magically equipped with the discernment and maturity necessary to navigate the entirety of the adult world without issue. Speaking as someone with more than two decades of work experience, it’s also plainly obvious to anyone that steps outside and interacts with others that many people well over the age of 30 (or 40, or 50, or so on) are not equipped with the discernment and maturity necessary to successfully navigate a turn signal, much less any appreciable portion of the adult world.

Even so, I doubt anyone would seriously recommend we make the legal age of adulthood, say, 50 or so, contingent upon completing a successful signaled lane change.

Just one signaled lane change. That’s all I ask.

I also understand that brains mature (and, sadly, sometimes decay) as they age. Scientifically, it’s clear that our brains continue developing well into our 20s. Given that, should we wait to legally define someone as an “adult” until their brain has fully matured?

It’s a fair question.

Unfortunately, this is not a question science can answer. What it means to be an adult is a philosophical question, not a scientific one. Being an adult has meant different things at different times in different societies. Even in our current time and society, being an adult means something very different to a single mother just graduating high school than it does for a college student living with their parents in their childhood home while they go to a local university. Becoming an adult and what it even means to be an adult, in other words, is a function of society, expectations and material conditions.

Legally, however, we are a country containing many different societies, each operating according to wildly divergent expectations, with obviously unequal material conditions. Consequently, when we’re talking about legality, it’s a question that’s best answered as an exercise in seeking a lowest common denominator. By what age are people most commonly in control over their own lives, at least as much as any of us are in control of them? By what age can we reliably hold people accountable for their choices?

Currently the answer to that question, legally speaking, depends on the choice the person is making. If you’re making choices that society broadly favors, the age of adulthood is 18. On the other hand, if you engage in what society deems a vice, the age of adulthood might be closer to 21. If you engage in what society deems a crime, on the other hand, the age of adulthood might be closer to 12 or 13, unless the crime you commit is also a vice, in which case you might be prosecuted as both a child and an adult simultaneously.

Our working legal definition of adulthood is a definition of convenience. When it’s convenient for our society to treat someone as an adult, like when they commit certain crimes, join the military or sign a bank note for several thousands of dollars worth of student loan debt, we treat them as adults. When it’s otherwise inconvenient or uncomfortable to our society, on the other hand, we push the age of adulthood out a little further until we feel better about ourselves and the choices these new adults are making.

This legally codified attitude of convenience has costs.

Punishing children as adults so we feel “tough on crime” has gone a long way toward building our world-beating incarceration rate. Race far too often decides which teens are tried as adults and which ones are treated as inherently rehabilitatable. Charging teens for “distributing child porn” when they send a racy message to a friend only advances the comfort of adult busybodies that don’t believe anyone should send racy messages.

On the other hand, treating young adults as children has gone a long way toward sustaining America’s unusually unhealthy drinking culture. Over 100 university presidents signed on to the Amethyst Initiative to rethink our nation’s drinking age over a decade ago due to the secretive and destructive culture of underage drinking that was created as a result of shifting the legal drinking age from 18 to 21. Thanks to the recently signed spending bill that slipped in a higher smoking age for what surely must have been fiscal reasons, that same pressure will be applied to tobacco consumption as well.

Finally, at some point we need to accept that, yes, 18-year-olds have sex. Sometimes, they even have sex for money.

No, 18-year-olds don’t always make good decisions around sex, alcohol, tobacco, or anything else. A lot of times, the decisions they make aren’t particularly convenient for the rest of us. However, it’s actually possible to encourage them to make better decisions if we let them make their decisions out in the open. Given the decisions we already let them make on their own and the countries we ship them to where they make some of those decisions, it’s well past time we stop moralizing and comforting ourselves and start acting like adults by treating adults like adults.

David Colborne has been active in the Libertarian Party for two decades. During that time, he has blogged intermittently on his personal blog, as well as the Libertarian Party of Nevada blog, and ran for office twice as a Libertarian candidate. He serves on the Executive Committee for both his state and county Libertarian Party chapters. He is the father of two sons and an IT professional. You can follow him on Twitter @DavidColborne or email him at [email protected].