Once, on a river-rafting trip through the Grand Canyon, I traveled with a charming, good-humored man who happened to run an oil rig in the Gulf of Mexico. He liked to rail against Nancy Pelosi, who had recently become the Speaker of the House. One day I told him that I, too, disliked Pelosi, because she was well to my right on many issues. The man was staggered; he’d imagined that she defined the leftmost rim of the universe, beyond which nothing existed.

When the oilman was on land he lived in Colorado Springs; I’m a San Franciscan. Geography alone made us exotic species to each other. And the river trip came during a period in 2009 when I frequently found myself telling strangers, in frustration, that people in my hometown could be as closed-minded as any right-wing community. We were all living in our respective bubbles, preaching to our respective choirs; I was looking for more substantive exchange. Yet what transpired in my conversations on the raft was not, in the end, especially illuminating. I enjoyed the oilman’s Texas vernacular, and we found common ground in our appreciation for buttermilk biscuits, but neither of us changed the other’s mind about the fossil fuel industry, and neither tried to, which may be why the encounter seems so pleasant in recollection.

The phrase preaching to the choir properly means hectoring your listeners with arguments they already agree with, and it’s a common sin of radicals, the tendency to denounce others as a way of announcing one’s own virtue. But it can be applied too widely, to malign conversation between people whose beliefs happen to coincide. The phrase implies that political work should be primarily evangelical, even missionary, that the task is to go out and convert the heathens, that talking to those with whom we agree achieves nothing. But only the most patient and skillful among us can alter the views of those who disagree profoundly. And is there no purpose in getting preached to, in gathering with your compatriots? Why else do we go to church but to sing, to pray a little, to ease our souls, to see our friends, and to hear the sermon?

I asked Katya Lysander, who sings ancient and modern Eastern European music with a Chicago choral group, what she thought of the phrase. She pointed out that there are in fact four audiences in a church service — the congregation, the choir, the preacher, and God. A priest preaching directly to the choir would be facing the wrong way, away from the congregation, as the choir is usually behind or on either side of the pulpit. And, as Lysander might have added, the preacher also listens to the choir, to her bishops, her colleagues, her congregation. And then everyone catches up on the church steps after the service. The ecclesiastical conversation, that is to say, consists of a series of exchanges among people in many different roles.

What’s more, to suggest that you shouldn’t preach to the choir is to misunderstand the nature of preaching. Conversion or the transmission of new information is not the primary aim; the preacher has other work to do. Classically, the sermon is a kind of literary criticism that regards the key sacred texts and their meanings as inexhaustible. Adults, like children, love hearing the great stories more than once, and most religions have prayers and narratives, hymns and songs that are seen as wells of meaning that never run dry. You can go lay down your sword and shield by the riverside one more time; there are always more ways to say how once you were blind and now can see.

Karen Haygood Stokes, a minister in Grand Rapids, Michigan, who formerly belonged to the San Francisco Symphony Choir, explained to me that her aim is not so much to persuade people to believe as it is to encourage them to inquire into existing beliefs. “My task as a preacher is to find the places of agreement and then move someplace from there. Not to change anybody’s mind, but to deepen an understanding.” The common ground among her parishioners is not the destination; it’s the starting point: “Have we thought critically about why we agree?” It’s a call to go deeper, to question yourself.

The primary assumption behind the idea that we shouldn’t preach to the choir is that one’s proper audience is one’s enemies, not one’s allies. This becomes especially true during election season, the prevailing view being that elections are won not by focusing on the base but by flipping the opposition. By this reasoning, all that I write and say during those cycles should be pitched at my adversaries, to recruit them. I have often been admonished that my statements should give no offense to strangers with whom I have little in common, that I should say things — I’m not sure what these cottony words would be, or whether I contain them — that will not irritate or alienate. I should spend my efforts on people who disagree passionately with me, because why waste time on those with whom I’ve already formed relationships and share interests?

One of the most excruciating rites of recent presidential elections was the debates in which “undecided” or swing voters were brought in to ask questions of the candidates. The premise behind the spectacle is that candidates win by competing for those not sure of whether they are for or against civil rights, tax cuts for the rich, and so on. Yet much evidence suggests that political organizations benefit most from motivating those who already agree with them, and that the Democrats in particular find the most success by pursuing people who don’t know whether they’ll vote, rather than how they’ll vote. This means reaching constituents who, historically, have been less likely to go to the polling booth: the poor, the young, the non-white. Republicans know this, which is why they’ve worked hard to perfect voter suppression tactics that target those populations.

Nevertheless, centrist Democrats often go wooing those who don’t support them, thereby betraying those who do. It’s as though you ditched not only your congregation but your credo in the hope of making inroads among believers of some other faith. You think you’re recruiting; really, you’re losing your religion. This has been true with welfare “reform,” with the war on terror, with economic policy, with the fantasy of winning over “the white working class”: time and again, misguided attempts to bring in new voters have offended existing constituencies.

This year, in an effort to appeal to a more conservative demographic, some Democrats went so far as to slacken their commitment to reproductive rights, dismissing them as “identity politics” and deeming them less important than economic justice. As many women have pointed out, however, such a stance constitutes a failure to understand that until and unless this half of the population can control their bodies and plan their families, they cannot be economically equal. The question is one of both strategy and principle: Do you win by chasing those who don’t share your views, or by serving and respecting those already with you? Is the purpose of the choir to sing to the infidels or inspire the faithful? What happens if the faithful stop showing up, donating, doing the work?

One reason we emphasize conversion is that we tend to believe that ideas matter more than actions, that beliefs directly determine behavior, that a preponderance of agreement will result in political and social change. In years past, I’ve often heard people obsess over polls that revealed how many Americans think climate change is real. They seemed convinced that if everyone could be made to believe, the crisis would be solved. But if people who believe climate change is real and pressing do nothing to address the problem, nothing happens. Not only is it unlikely that everyone will agree, it doesn’t matter whether they do, and it isn’t worth waiting for. There are still people who don’t believe that women are endowed with the same inalienable rights as men, and this hasn’t prevented us from creating policies that are based on the principle of equality between the sexes.

What matters is that some of us act. In 2006, the political scientist Erica Chenoweth set out to determine whether nonviolence was as effective for regime change as violence. She found, to her surprise, that nonviolent strategies worked better. Organizers were enthralled by her conclusion that only around 3.5 percent of a population was needed to successfully resist or even topple a regime. In other words, to create change, you don’t need everyone to agree with you, you just need some people to agree so passionately that they will donate, campaign, march, risk arrest or injury.

The majority of Americans, according to Gallup polls from the early 1960s, did not support the tactics of the civil rights movement, and less than a quarter of the public approved of the 1963 March on Washington. Nevertheless, the march helped push the federal government to pass the 1964 Civil Rights Act. It was at the march that Martin Luther King Jr. gave his “I Have a Dream” speech — an example of preaching to the choir at its best. King spoke to inspire his supporters rather than persuade his detractors. He disparaged moderation and gradualism; he argued that his listeners’ dissatisfaction was legitimate and necessary, that they must demand drastic change. White allies were needed, but black activists didn’t need to wait for them. Often, it’s an example of passionate idealism that converts others. The performance of integrity is more influential than that of compromise. Rather than meet people where they are, you can locate yourself someplace they will eventually want to be.

The choir is made up of the deeply committed: those who show up every Sunday, listen to every sermon, and tithe like crazy. The time the choristers spend with one another, the sum of their sympathy and shared experience, is part of what helps them sing in unison and in tune. To win politically, you don’t need to win over people who differ from you, you need to motivate your own. There are a thousand things beyond the fact of blunt agreement that you might need or want to discuss with your friends and allies. There are strategy and practical management, the finer points of a theory, values and goals both incremental and ultimate, reassessment as things change for better or worse. Effective speech in this model isn’t alchemy; it doesn’t transform what people believe. It’s electricity: it galvanizes them to act.

“Correspondence,” that beautiful word, describes both an exchange of letters and the existence of affinities; we correspond because we correspond. As a young woman, I had long, intense conversations with other young women about difficult mothers, unreliable men, about heartaches and ambitions and anxieties. Sometimes these conversations were circular; sometimes they got bogged down by our inability to accept that we weren’t going to get what seemed right or fair. But at their best, they reinforced that our perceptions and emotions were not baseless or illegitimate, that others were on our side and shared our experiences, that we had value and possibility. We were strengthening ourselves and our ties to one another.

In an intellectual exchange, disagreement doesn’t mean tearing down a rival but testing and strengthening the structure of a proposal, an analysis. It is what you do when you agree with people in general but have specifics to work out; and that work can be a joy. It’s an arrangement in which no one is the preacher or the choir, in which everything is open to question, in which ideas are beautiful and precision is holy.

Though great political work and useful debate about ideas and ethics is happening over social media, much of the time we spend together (or in solitude) has been replaced by the time we spend online, in arenas not conducive to subtlety or complexity. We have shifted to short declarative statements, to thinking in headlines, binaries, catch-all categories, to viewing words as pieces in a game of checkers rather than, say, gestures in a ballet. If you’re confident that everything not black is white, discussions about shades and hues seem beside the point. This absolutism presumes that our only position on those with whom we don’t have complete agreement is complete disapproval, and also that agreement is simple, past which there is no nuance, strategy, possibility to explore.

Absolutism is obviously antithetical to practical politics, which, of course, depend on understanding and sometimes working alongside those with whom you may not agree, or with whom you agree on some things and not on others (as I learned in antinuclear political gatherings in the 1980s, when downwinder Mormons, punks, pagans, Japanese Buddhist monks, Franciscan priests and nuns, and Western Shoshone elders worked together pretty well). Maybe it’s antithetical to the human condition, where we must coexist with difference and make the most of our journeys in increments.

To dismiss the value of talking to our own is to fail to see that the utility of conversation, like that of preaching, goes far beyond persuasion or the transmission of information. At its best, conversation is a means of accomplishing many subtle and indirect things. The painter Rudolf Baranik, who died twenty years ago, once told me a story about a ferry ride he took in New York City on a bitter winter day in the late 1930s, soon after he had arrived as a refugee from Eastern Europe. “It is very cold, is it not?” he said in his formal English to a black man standing next to him on the deck. “Yeaaahh, man,” his fellow passenger replied. “Why is that man singing?” Baranik wondered. The moment remained with him — the unfamiliar musicality of the New Yorker’s intonation had made memorable what was otherwise an ordinary exchange. Why comment to a stranger about the weather, when the conditions are obvious to both of you? Because it’s an affirmation that you exist in the same place, that no matter what else might separate you, you have this in common. And because it’s an opening, if not to understanding, then at least to the place where it might begin.

Karen Stokes told me she thinks of the choir as providing a space that is the near opposite of the combative culture of the internet. “In so many churches that I’ve served, the choir is the primary support group. They meet every week; they hang out together, put in extra time on Sunday, have made a commitment to one another. You can’t just drop in and say, ‘Let’s sing this or I’m leaving.’ Everyone has submitted themselves to something bigger: to the creation of music and, in the church setting, music for the worship of God.”

Within most examples of broad consensus lie a host of questions and unresolved differences. Agreement is only the foundation. Yet from here we can build strong communities of love, spirited movements of resistance. “We cannot walk alone,” Dr. King said that day in 1963. Find people to walk with — and talk with — and we find power as well as pleasure.