To most readers who recognise the name, Amy Chua is the author of Battle Hymn of the Tiger Mother, the bestselling memoir about bringing up children under a strictly traditional regime of Chinese parenting. The book seemed to repel and inspire in equal measure. But leaving aside its personal testimony, it was a work that dared to tread on disputed and dangerous terrain: the advantage of certain ethno-cultural traits.

It’s an issue that can be found to varying degrees in all five of Chua’s books, including her latest, Political Tribes: Group Instinct and the Fate of Nations. Chua, a professor of law at Yale Law School, believes that ethnic and tribal identity plays a more powerful role in national politics than has been previously acknowledged, at least by American foreign policy.

She cites the wars in Vietnam and Iraq as classic examples in which intranational differences were underestimated with catastrophic results. In Vietnam, she notes, “a hugely disproportionate number” of the country’s “capitalists” were ethnic Chinese, who were despised by the Vietnamese, both northern and southern.

Chua tries to shoehorn international relations, domestic strife and campus activism into one category of tribal impulses

Therefore, America’s pro-capitalist initiatives served mainly to inflame existing resentments. The mistake was repeated in Iraq, but this time with religious divisions. The reason for this political dereliction, she argues, is because of the self-image America blindly projects on to the rest of the world.

America tends to see itself as a democratic polity in which ethnic differences are subsumed into a shared identity. Which is to say that there may be African Americans, Chinese Americans and Italian Americans, but what counts above all is that they are Americans.

As she observes elsewhere in the book, this is as much a myth as a reality. Many African Americans do not feel “American” in the way that many white Americans take for granted. And here she suggests that while America has enjoyed great success as a melting pot, its failures – discrimination, injustice, inequality – stem from this unwillingness to recognise the importance of ethnic and tribal affinities.

As far as it goes, that’s a thesis that is unlikely to provoke a storm of dissent for the good reason that it’s large incontrovertible. However, it’s when Chua attempts to expand her argument into the ever more complex world of identity politics that the book begins to lose its way or, rather, the picture blurs into a series of on-the-one-hand, on-the-other hedges.

It’s partly because Chua tries to shoehorn international relations, domestic strife and campus activism into one overarching category of tribal impulses. But it’s also because that while she’s adept enough at diagnosing tribal behaviour, she doesn’t seem to have a clear idea about what to do about it beyond acknowledging its existence.

So yes, we can ruefully nod our heads when she quotes President Obama saying: “The degree of tribal division in Libya was greater than our analysts had expected”, but that doesn’t really tell us about how to deal with tribal societies other than, perhaps, to stay away from them. And it doesn’t tell us anything about the more modern kind of tribalism that is increasingly a feature of Anglo-American politics. As Chua notes: “Once identity politics gains momentum, it inevitably subdivides, giving rise to ever-proliferating group identities demanding recognition.” But should these identities – the “more than 50 gender designations”, for example, that Facebook now lists – be given recognition, much as the Obama administration recognised the 140 tribes that make up the Libyan people?

She seems to imply that the current fragmentation of society, its breaking down into ever more tightly defined groups competing for recognition and power, is a recipe for conflict. And certainly there is little doubt that the progressive forces of the left that once sought an inclusive universalism are now increasingly devoted to an exclusionary discourse in which various markers of privilege – whiteness, maleness, able-bodiedness – are deemed as barriers to understanding and participation.

But if there is a way out of this cul-de-sac of victimhood, Chua hasn’t found it. “What holds the United States together,” she concludes in a confusing epilogue, “is the American Dream. But it must be a version of the dream that recognises past failure instead of denying it.”

It’s a suitably lame note on which to end a well-intentioned book that never quite comes together.

• Political Tribes: Group Instinct and the Fate of Nations by Amy Chua is published by Bloomsbury (£20). To order a copy for £17 go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99