The 2016 presidential election, particularly the primaries, has made me feel old.

At one point I found myself listening to a young friend talk about all the idealistic reasons why he was supporting Bernie Sanders over Hillary Clinton, and I thought, "Twenty years ago, that's exactly what I would have said." And now polls are showing Hillary Clinton running significantly behind the support Barack Obama got among young voters, in large part because they're expressing unusually large support for Gary Johnson and Jill Stein.

This is hardly the first election in which young Democrats were underwhelmed by the party's establishment favorite and gravitated toward the candidate who seemed like more of an outsider, whether it was Howard Dean or Jerry Brown or Obama himself (the only one who actually won). What's different now is that young people are really taking their time coming around to the nominee. That third-party support will probably fade as we get closer to election day and the choice between Clinton and Donald Trump takes on increasing urgency. But in the meantime, there are a lot of young people the Democrats should have on their side, but who aren't ready to commit.

Allow me to offer some reasons why they should really think about abandoning their third-party flirtations.

1. These third parties are lame.

You can lament the lack of options beyond the Democrats and Republicans while still acknowledging how weak and ineffectual the Greens and Libertarians are. It's true that our system is built to marginalize them — because we don't have proportional representation as they do in many parliamentary systems, a third party could win 10 or even 20 percent of the vote in every congressional district and still wind up with zero representatives in Congress. But the Greens and Libertarians never get anywhere in large part because they focus so much on the one office they have zero chance of ever winning, the presidency.

If you want to build a party over the long run and have a chance at wielding power, you need officeholders who can begin putting your vision into action. That means finding the places where you have a chance to actually elect someone — like in city council races where voters choose multiple candidates — and focusing your efforts there (the Greens do have some officeholders, but it's a pretty limited list and most of them are in California; the Libertarians haven't done much better).

Even if you find yourself in agreement with the Greens or Libertarians, the truth is that they're not particularly good at politics, and voting for their presidential candidates will only encourage them to stay on the fruitless course they've been on for decades. What exactly will they achieve if their presidential vote total this year is a couple of points higher than it was four years ago or four years before that? More influence over the policy course of the federal government? Of course not. So if you want to help them, you'll have a much greater impact giving your vote, time, or money to a local candidate than to Jill Stein or Gary Johnson.

2. Your presidential choice doesn't need to be a perfect and complete expression of your identity.

We make lots of choices that say a great deal about who we are: the music we listen to, the clothes we wear, the place we choose to live, the work we do. But some choices are ruthlessly pragmatic. If I'm buying a pair of toenail clippers, I don't need them to embody the fullness of my immortal spirit; I just need them to do the job. The presidency is more similar to that than you'd think. Any president is going to fall short of what you'd like and even piss you off in some ways before their term is up. The question is whether, on balance and on all the issues they'll touch, they'll do the most good. There's nothing wrong with saying that this isn't the president you'd choose in the best of all possible worlds, but in this imperfect world at this imperfect moment, this is the best of the available options.

3. It's fine to vote against someone and not for someone.

There are plenty of people now saying, "Sure, Donald Trump is a nightmare, but I just don't like Hillary Clinton." Well, choosing simply to avert catastrophe is perfectly legitimate.

Over the course of your life, if you're lucky you'll be able to vote for one or two candidates whom you love without reservation. If it doesn't happen this time, maybe it will in four or eight or 12 years. But this is the only chance you'll have to vote against Trump. Even though in every election people say, "This is the most important election of our lifetimes," this time it may actually be true, not because paradise awaits if we make the right choice but because disaster awaits if we don't. And as Brian Beutler recently wrote, if you're thinking of using your vote to "send a message," there are few more important messages than that "if you try to win the presidency by stoking race hatred and promising to degrade the Constitution, you will lose and lose badly."

4. Check your privilege.

How will the outcome of the election affect people who aren't like you? If Republicans win the White House (which means controlling judicial appointments) and hold on to Congress, among other things they'll move to restrict abortion rights, toss 20 million people off their health coverage, cut back the social safety net, restrict voting rights, and ramp up deportations of undocumented immigrants. None of that might affect you, but there are a lot of people who will be affected quite a bit. You can think of your vote as an altruistic contribution to the welfare of others.

5. Your chances of seeing the change you want might actually be better from inside one of the major parties.

Many young people like Johnson's advocacy for marijuana legalization, while Clinton has essentially said she wants to wait and see how things go in places like Colorado and Washington before she'll consider full legalization. But even if you think Johnson is right, how does increasing his vote bring us closer to the day when we see national legalization? The Democratic Party has been moving left on this issue as the public has evolved on it. That's what parties that worry about winning elections do: They change in response to the voters. It's why the Democrats are more liberal on issues like gay rights and immigration than they were a few years ago. We may get legalization within a few years, but if it happens it won't be because Gary Johnson said it was a good idea, it'll be because the Democratic Party eventually embraced it and Republicans were unable to resist. That's what happened with same-sex marriage: It started as a fringe position, then more and more Democrats embraced it until it eventually became the consensus within the party, and finally the laws were changed.

Voting is an expressive act. We use it in part to say something about who we are, what we believe, and what we value. It also says something about our relationship to the world not just as it might be but as it is. There are legitimate reasons why after carefully weighing all the factors at work, some people will still choose to vote third party. But it's also worth considering whether doing so is the most effective way to achieve the goals that attracted you to the third party in the first place.