It is a mark of the problem that The Persuaders seeks to describe that I had to force myself to sit down and read it. Anand Giridharadas, well known in the US as a journalist and TV political pundit, has written a thinky book on a subject many of us may feel we’ve heard too much about already – namely, the feedback loops, filter bubbles and interference of Russian bot farms that have led to extreme polarisation in the US and beyond. Giridharadas describes this state of affairs as “Americans’ growing culture of mutual dismissal”, leading to a mass “writing-off from a distance” and the inability of anyone to change their minds about anything. In overview, it looks like a book borne of Twitter discourse, and who needs that?

As it turns out, The Persuaders is, well, persuasive, with a mission to find solutions for all this by identifying strategists, activists and thought leaders who have broken through entrenched political indifference or partisanship to build bridges or win over new fans. If the understanding is that no one will cede an inch to the other side, Giridharadas seeks cheering counter-examples, from the coalition behind the 2017 Women’s March, to the explosion in mainstream support for Black Lives Matter, to the rise of figures such as Alexandria Ocasio-Cortez – her modern campaigning style is studied usefully alongside the less flexible and successful style of Bernie Sanders. The book grapples with the dangers of political purity and how to persuade people from the centre right and flabby middle to the left without diluting the cause. Despite the occasional cuts-job vibe of books by busy media operators, I found it a useful, thoughtful and interesting read.

Which is not to say it didn’t annoy me. That’s the point, I suppose. The clever thing about Giridharadas’s approach is that while dissecting the prejudices of others, he flushes out your own kneejerk reactions, a dynamic from which the author himself isn’t spared. In the chapter on the Women’s March, the Palestinian-American activist Linda Sarsour, one of the organisers, describes how alienated she was by the movement’s roots in “white feminism”. There are readers who, presented with other names from the Women’s March leadership team, will have an equally forceful recoil, thanks to their perceived links with antisemitic figures.

The concern around white feminism is given many pages of thoughtful discussion. The latter worry, triggered by support among some march organisers for Louis Farrakhan, the antisemitic leader of the Nation of Islam, is given half a sentence. One requires understanding; the other is largely dismissed.

The effect of this, deliberately or otherwise, is to underscore the need for everyone to consider the alternative view. Multiple interviewees with decades of activism behind them express frustration at the present state of leftwing politics and its habit of either occupying a drippy middle ground or else digging into the narcissism of small difference. In the era of no microaggression going unpunished, the book makes the case through various veteran activists that not only is the purity spiral counterproductive to broadening the movement, it is, for those pursuing it, almost addictively recreational. As the author writes: “Social media rewarded the hunt for apostates more than the conversion of non-believers.”

Loretta Ross, a pioneering activist and theorist in Black radical feminist tradition, puts it this way: “I think the 90-percenters spend too much time trying to turn people into 100-percenters, which is totally unnecessary.” She means those ostensibly on the same side who say: “If you’re not working on my issue from my angle, then you’re erasing my issue. If you’re championing economic justice, you’re problematic for minimising race. If you’re championing racial justice, you don’t post enough about the ills of capitalism. If you’re focused on long-term climate change, you’re neglecting the here-and-now needs of poor communities.” These fights only hurt the progressive cause. It’s OK to call people out, but understand what you’re reaching for, she says. “You can’t change other people. You can’t even change the person you’re married to. You can help people. You can expose people to different information and help them learn – if you do so with love.”

What this means in some contexts, argues Giridharadas, is shelving what feels good for what actually works. One chapter studies a fascinating programme trying to stop rapists reoffending by educating them on feminism, which requires a huge emotional effort on the part of the female educators to overcome what Ross calls “the justified instinct to focus on those hurt by the problem, not those perpetrating it”. Who wants to put resources into engaging with a rapist at the expense of funding his victims? But if it’s the most effective way to reduce rape, it’s at least worth considering.

The most skippable stretch of the book is a long, Wikipediaesque biography of Ocasio-Cortez, all well-rehearsed information by this point. And there are occasional, inadvertently funny passages. An account of a consciousness-raising group of white people trying to become better educated about their own race privilege contains a testy back and forth over whether the description “recovering racist” implies that they are, in fact, racist, that is pure Monty Python.

By far the most fascinating and potentially useful case study is that of Anat Shenker-Osorio, the communications strategist for progressive causes, whose tactics, pegged to the data, have exposed a lot of shortfalls in leftwing political campaigning. Shenker-Osorio points out that when people get frightened, they skew right; when they feel compassion and common cause with their fellow humans, they skew left. The left has often made the mistake of tailgating on the right’s framing of a discussion, piping up “We too are tough on law and order!” rather than calling out the right’s way of sowing disagreement between groups. “What is it about winning that is distasteful to you?” she says drily to a campaigner fixated on small differentials in language. She also counsels the left to cheer up. “Many progressive and Democratic messages basically boil down to ‘Boy, have I got a problem for you!’” – proven to be a big downer at the polls. “You’ve got to sell people on the beautiful tomorrow.”

Exacerbated by new technology, these are, nonetheless, very old problems. As Saul Bellow put it in The Adventures of Augie March: “That’s the struggle of humanity, to recruit others to your version of what’s real.” This enjoyable, helpful read may, paradoxically, suspend our solipsism for long enough to better prosecute that recruitment.

• The Persuaders: Winning Hearts and Minds in a Divided Age by Anand Giridharadas is published by Allen Lane (£20). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply