When I moved from South Korea to Australia at the age of eight, I learned the worst part of crossing language lines was adjusting to live conversation – to its rapid, layered rhythms and many about-faces. Once spun out, the best I could do was wait for a topic change or long pause to regain a foothold. Tripping over loose words and broken sentences, I never got far.

This was a problem because there were many things I did not understand about my new home – why all public figures (including politicians) presented as sports fans, why strangers were called “mates”, why none of the food was spiced. Unable to ask questions, let alone to raise objections, I began to wear a distant smile and to retreat into the private corners of my mind.

When I told Mum and Dad of my frustrations, they told me to be empathic: “Try to imagine things from their perspective.” Teachers described empathy as a characteristic of model students; at church, the pastor referred to it as a godly virtue. In my mind, empathy took on the mythic allure of a panacea, but it remained elusive in real life. The differences between my peers and me seemed to pose a distance too great to bridge.

Things changed for me when I joined my primary school debate team. I had been attracted to the activity by the promise of attention – a few minutes in which I couldto speak uninterrupted. But I also discovered a trove of wisdom, including a new way of thinking about empathy.

I chased these insights for 15 years, winning two world championships and coaching the Harvard and Australian national debate teams along the way. The experience led me to become a newspaper reporter and now a law student. It left me convinced that debate can help us improve our lives and communities in these polarised times.

Consider the rules of debate: two sides are randomly assigned to argue for and against a topic – say, that we should abolish student debt. Each speaker has equal time to speak before an impartial adjudicator, who awards the more persuasive team.

To win a debate, one must understand not only one’s own case but also that of the other side. The best debaters come to such double vision through a strict process. In the last moments of preparation before a round, they go through a series of exercises known as “side-switch”.

One involves taking out a fresh sheet of paper, placing oneself on the opposite side of the topic and brainstorming the four best arguments for this new position. Another is to review one’s own case through the eyes of an opponent, brainstorming the strongest possible objections.

The exercise provides a wealth of strategic insights, but also has an important side-effect. For a time, we debaters feel what it is like to believe ideas that contradict our own. We trace the steps a sensible person (like us) can take to arrive at conclusions that might seem alien. From this switched position, we consider the possibility that we are wrong.

Together these aspects of side-switch form an unusual view of empathy. Whereas most people view empathy as a spontaneous psychic connection or a reflection of virtue, debaters know it as an understanding achieved through a series of actions. It is the result, and reward, of work.

Any group – whether a family, a workplace, or a nation – has to manage its disagreements, but today so many of our arguments are hostile, useless and painful. We are, in a word, stuck, shouting at one another from a distance, fixed in our respective places. The resulting enmity and contempt undermine the basic aspiration of liberal democracy: to build a society around, and not in spite of, people’s differences.

Habits of mind such as the side-switch can help us become unstuck. They dislodge our complacency and force us to consider the other side, not so that we may avoid disagreeing, but so that we may disagree better. They require neither genius nor virtue, only paper and pen.

Debate contains many other lessons – from constructing (and dismantling) arguments to deciding when a dispute is worthwhile – that can help us disagree better in everyday life. The activity trains us to change other people’s minds with nothing more than words. It reveals the physics of our disagreements, so that even school-age children may wield them.

Though this education has historically been the mainstay of elites, many alums have found in debate the resources to overcome disadvantage. The incoming US supreme court justice, Ketanji Brown Jackson, has said of her time as a debater: “I gained the self-confidence that can sometimes be quite difficult for women and minorities to learn at an early age.”

In practice, few activities are more efficient than debate at uncovering flaws in our thinking, then spurring us on to repair them. For this reason, entrepreneurs have sought to capitalise on internal dissent. The investor Warren Buffett once proposed that company boards should hire two advisers on potential acquisitions – one to advocate for the deal and the other to oppose. Netflix’s “culture” memo contains the line: “The bigger the decision, the more extensive the debate.”

This is no innovation. Competitive debate grew out of English pubs and coffeehouses that, beginning in the 17th century, hosted spirited discussions about the proceedings of parliament. Its roots extend back to the Ancient Greek custom of participation through oration.

In our age of polarisation, we have lost shared values and truths, but we have also lost the skills of thoughtful, empathic argument – and the will to invest in them. As widespread disillusionment with traditional institutions has coincided with declining confidence in our fellow citizens, an ethic of “finding our people” (and disregarding the rest) has come to dominate.

While thinking about the value of debate in such times, I find myself returning to the concept of empathy. The side-switch drills reflect in miniature the training debaters receive. Over a long enough career, debaters argue both sides of most topical issues. Since they neither choose their side nor the topic, they flirt with ideas, unencumbered by expectations of consistency or deep conviction.

Granted, the capacity of debaters to argue both sides of every issue has its downsides. Everywhere in the public sphere one sees the corrosive effect of mercenary speech. Silver-tongued politicians make an art of bending bend with prevailing winds. Unscrupulous media pundits draw false comparisons and advance the agenda of the highest bidders. In this context, the news that Boris Johnson once drafted an op-ed in favour of remaining in the European Union, as a brainstorming tool, elicits cynicism and despair. The Oxford Union debates, where Johnson and his peers trained, now appear online with the disclaimer: “The speaker in this video is a competitive debater and therefore the views expressed may not necessarily represent their beliefs.”

Indeed, most debaters experience, at some point in their career, doubts about the ethics of their sport. The novelist Sally Rooney wrote in the Dublin Review of her career as a champion debater: “I no longer found it fun to think of ways in which capitalism benefits the poor, or things oppressed people should do about their oppression. Actually, I found it depressing and vaguely immoral.”Some experienced competitors describe themselves as Hamlet, able to see both sides but incapable of committing to either one.

I do not believe that debate is inimical to conviction but I see that it requires us to rethink the term. The conventional view is that strong beliefs are what we bring into a discussion. In debate, convictions are what we take out of such a conversation. The aim is not to safeguard our prior beliefs, but to play and experiment until we stumble on ideas worthy of our commitment. Such exploration can result in confusion and indecision. It also avoids the false clarity of dogma.

Debate can enable fakes and opportunists. This aspect of the activity – its fondness for spectacle and insistence on experimentation – requires careful management. But if debate graduates some mercenaries, it also trains the rest of us to recognise their tactics and to counter them. It immunises the population against the abuses of language and argument.

I knew none of these things when I stumbled on to my school debate team. Yet I sensed that I could be on the cusp of some great transformation. As I sat onstage in the assembly hall, scribbling down the best arguments for the other side, I felt the distance between me and my opponents begin to narrow. Then, as I stood and faced the hushed silence of the assembled crowd, I felt my voice, green and insistent, ready to announce itself.

The Art of Disagreeing Well by Bo Seo (William Collins, £18.99). Buy it for £16.52 at guardianbookshop.com