I am lucky enough these days to be in regular touch with young people — students — who are interested in public service. I find hope in their quality, energy, and motivation, and they press me to think more deeply about what it takes to pursue a life in the public realm.

In trying to answer that question, I’ve come to believe that at the heart of it all — indeed, at the heart of representative democracy itself — is persuasion. If you’re trying to improve society you have to persuade other people: about issues, facts, proposals, legislation, strategy, tactics… In fact, the only way to get things done is to convince other people to join in. If we can’t persuade them, we can’t move forward.

I was seated once in a private airport terminal, waiting for a plane to fly me home to Indiana. Someone walked in, and I looked up to find Martin Luther King Jr. He was alone. This was a bit before the peak of his celebrity, but most Americans would have recognized him even then. We chatted for a long time as we waited, and one of the things that struck me most deeply was that he was a minister of the gospel and a civil rights leader, I was a politician, yet we shared a deep and abiding interest in the question of how you persuade people to your side.

I saw the same quality in another masterful public figure, Lyndon Johnson. Not only was he a remarkably persuasive politician himself — he always had on his mind, “What do I have to do by word or by deed to get your support?” — but he was a student of how effective or ineffective others were.

From time to time, he’d have members of his cabinet speak to a group of assembled members of Congress, sometimes just a small group of us, sometimes a large roomful. He would take a seat in the front row, turn his chair around so that his back was to the speaker, and look out over the room. It was clear he wasn’t interested in what they were saying; he was interested in the impact of what they said. In other words, he was interested in whether or not they were persuasive.

In a democracy like ours, you need help from allies, partners, friends, sometimes even antagonists — because you’re trying to find common ground on a particular issue and build coalitions of support. This means that you have to convince others to do something for your benefit, which is difficult. Your chances are best when you can convince them that it’s in their best interest.

To do so, you have to listen carefully, learn what’s important to them, and appeal to their values and interests. You also have to gain their trust, because if they think you’re a liar, you’re not going to persuade them to your side.

This, in turn, requires several things. Above all, you have to know what you’re talking about and master the facts. You need to study the issue at hand, so that you’re familiar with the arguments on all sides; being well-informed boosts your credibility.

And I was struck, when I was in Congress, by the tactics members used to appeal to people who often had different backgrounds, priorities and perspectives: they mentioned precedents, sought to connect to their listeners’ core values, compared their proposals to the alternatives, cited experts, and knew how much public support or major interest-group support they had.

This is how we decide things in this country: we listen, we argue, we cajole, we compromise, and we persuade. The whole process can get untidy, and it’s tough work in today’s polarized, hyper-partisan environment.

But as we continue to try to answer Abraham Lincoln’s 1863 question — whether a nation so conceived and so dedicated can long endure — here’s what I tell the students thinking of going into public service: that it is an extraordinary privilege to be part of a system, representative democracy, that gives you the opportunity to persuade others, and by doing so to chart the future course.

Lee Hamilton is a Senior Advisor for the Indiana University Center on Representative Government; a Distinguished Scholar at the IU Hamilton Lugar School of Global and International Studies; and a Professor of Practice at the IU O’Neill School of Public and Environmental Affairs. He was a member of the U.S. House of Representatives for 34 years.