His brutality is breathtaking, his ruthlessness unforgivable. Even as a celebrated conservative provocateur, Kevin Williamson might have mustered just a shred of sympathy for American "hillbillies" – if only because their votes could be key to blocking a Clinton return to the White House.

At the heart of Donald Trump's election campaign there is a daredevil's gamble that a foul-mouthed, risk-taking candidate can so demonise and offend black and brown voters that whites, especially the poorly educated, will rush to make him president – hence the courtship of the so-called hillbilly vote.

In the wake of a stunning hijack by Trump, the Republican Party is reduced to civil war. Wounded, Williamson speaks for a losing faction so, a bit like the American general who argued he had to destroy a Vietnamese village to save it, Williamson happily smears dysfunctional Rustbelt communities in faeces.

"They deserve to die," he writes in National Review. "Economically, they are negative assets. Morally, they are indefensible. Forget all your cheap theatrical Bruce Springsteen crap. Forget your sanctimony about struggling Rustbelt factory towns and your conspiracy theories about the wily Orientals stealing our jobs…

"The white American underclass is in thrall to a vicious, selfish culture whose main products are misery and used heroin needles. Donald Trump's speeches make them feel good. So does OxyContin."

There is some sympathy at the other end of the spectrum, but judgment there is harsh too – like this from John Marshall, in his Talking Points Memo blog: "Let's put this clearly, the stressor at work here is the perceived and real loss of the social and economic advantage of being white."

In the face of such dehumanising contempt, how were these communities to respond?

As it turns out, they have a voice. His name is J.D. Vance and his new book is Hillbilly Elegy: A Memoire of a Family and a Culture in Crisis – which one review describes as "a civilised reference guide for an uncivilised election".

Much like the lone survivor in a massacre, spared only so that he might tell the world of the ferocity of the attack, Vance beat the odds – and so has come down from the hill country with a message for America.

Helped by his grandmother, he got himself through school; into the US Marines; next to Ohio State University and then, something of a precedent, through Yale Law School. Age 31, he hangs out in Silicon Valley these days. A biotech executive, he writes: "I may be white, but I do not identify with the WASPs of the north-east. Instead I identify with the millions of working-class white Americans of Scots-Irish descent who have no college degree.

"To these folks, poverty is the family tradition – their ancestors were day labourers in the Southern slave economy, sharecroppers after that, coal miners after that, and machinists and millworkers during more recent times. Americans call them hillbillies, rednecks or white trash. I call them neighbours, friends and family."

Complex and human, Vance's elegy serves at times as a rebuff to Trump's wrecking-ball attacks on Hillary Clinton and Barack Obama as the embodiment of all that is wrong with Washington. Vance keeps economic hardship in the mix as a cause of his peoples' grief. But he argues that a much bigger issue is "hillbilly" culture, which "increasingly encourages social decay, instead of counteracting it".

Vance is articulate and empathetic in this unvarnished account of a hardscrabble life in Appalachia – he is tender about values held dearly, like loyalty, love of country; he's unapologetic about physical and verbal abuse; and about alcohol and drug abuse. As well, he mourns lost senses of purpose, community and even spiritual identity.

Spruiking the book on National Public Radio, Vance says of life in Ohio: "People used to rely on automotive jobs, steel mill jobs, coal jobs – and those things, for the most part simply don't exist. [Last year] in the county where I grew up, deaths from drug overdoses outnumbered deaths from natural causes – which is kind of extraordinary."

Vance's mother was a cot-case – violent, addicted to drugs, too many husbands and too many boyfriends. His grandmother was a saviour – as a child, she shot a man who stole the family cow; and as an adult, she'd douse her drunken husband with petrol and set him alight. But she also made the boy do his homework.

Alluding to the family confrontation by which he came to live with the grandmother who was known also as mamaw, Vance writes: "[She] told me that if mom had a problem with the arrangement, she could talk to the barrel of mamaw's gun. This was hillbilly justice, and it didn't fail me."

In Middletown, where he grew up in Ohio, a fifth of kids don't finish high school and only a few of the few who get to set foot in college, graduate. He writes of Middletown: "[It's] a town where 30 per cent of the young men work fewer than 20 hours a week and … not a single person [is] aware of his own laziness."

Vance writes of a neighbour "who was a lifetime welfare recipient, but in between asking my grandmother to borrow her car, or offering to trade food stamps for cash at a premium, she'd blather on about the importance of industriousness. 'So many people abuse the system, it's impossible for the hard-working people to get the help they need,' she'd say."

But in complaining of laziness, Vance addresses a sense of despair and what he calls "learned helplessness" – a term used by psychologists to describe how, after systematic pain, a victim surrenders control in a belief there is no way to avoid further pain.

And so the group cling to the likes of Trump who says they will have jobs and a good life and he'll have their backs – it helps too that the New York realtor and reality TV star repeatedly smacks down big corporations and big government as the roots of evil in today's US.

Despite, or because of the 1980s success by Ronald Reagan in luring them away from their long-held support for the Democratic Party, Vance reserves strong criticism for the conservative political movement. He writes of a fatalism in "hillbilly" culture, saying that from a young age they are taught that the cards are stacked against them, it's best to keep expectations low and they can't expect to overcome the bigger forces that shape their lives.

This is how Vance rips into conservatives: "They foment the kind of detachment that has sapped the ambition of so many of my peers. The message of the right is increasingly, 'it's not your fault that you're a loser; it's the government's fault'.

"Trump is telling many [in these parts of the country] that society and government is to blame for all their problems. A more helpful and hopeful message would encourage the white working class to take responsibility for their conduct and work ethic, and to act as good role models for their families, churches, and communities, rather than becoming enraged by divisive political debates."

Sadly, Trump wasn't looking for this underclass so that he might help them, so much as identifying a block of votes that could be manipulated in an ideological war that has simmered in American conservative political circles for decades – and in which Trump's success in the primaries revealed the extent to which the party has to remake itself to survive.

Even before Trump came on the scene, a small Republican movement, dubbed the "Reformicons", was demanding a policy and philosophy overhaul to acknowledge that middle and lower income earners were dudded by so much of what was enshrined as GOP orthodoxy, especially on taxes, trade and immigration.

That the 16 other contenders for the GOP nomination clung to those policies even as Trump was winning by shredding them, was a revelation. Trump at that stage was funding his own campaign, which meant he could do as he liked; the rest of the field was beholden to rich donors who demanded policies that served the billionaire class, not the working class.

The general election is becoming a referendum on Trump – and that's an arena in which he struggles. But the primaries were a referendum on the GOP establishment's stewardship of the party and its policies – and that the establishment lost is read by Columbia University historian Timothy Shenk as proof of the resumption of a guerrilla war against the party's "managerial elite".

And if Trump is the victors' standard-bearer, their bible is a weighty, 700-page tome published in June 2016. Titled Leviathan and Its Enemies, Shenk describes it as "digressive, repetitive and in desperate need of an editor" – but he also describes it as one of the most impressive books to come out of the US right in a generation – "and the most frightening".

Its author was the late Samuel Francis, an academic, sometimes congressional aid and writer for right-wing publications, who was driven by a belief that society was controlled by managers and experts who were a threat to traditional American values – "morality and religion, family, nation, local community, and at times, racial integrity and identity".

These he argued were sacred principles of a new "post-bourgeois proletariat" drawn from America's working class and the lower ranks of the middle class who were driven, according to the coded language of Francis' book, by "immutable elements of human nature [that] necessitate attachment to the concrete and historical roots of moral values and meaning".

If his meaning was unclear, he was perfectly clear in a speech he gave while working on the book, declaring: "What we whites must do, is reassert our identity and solidarity, and we must do so in explicitly racial terms through the articulation of a racial consciousness as whites."

In the early 1990s, Francis teamed up with CNN host Pat Buchanan who mounted a failed challenge to President George H. W. Bush for the GOP nomination in 1992. Francis urged Buchanan to make another run for the nomination in 1996 – as a champion of protectionism, foreign policy isolationism and anti-immigrant. Sound familiar?

Despite Buchannan's very limited success – he won the New Hampshire primary and nothing else – Francis was convinced that his so-called post-bourgeois proletariat understood increasing US diversity to be a measure of the dwindling power of white Americans.

When Buchanan did bomb out, Francis explained it away, arguing that Buchanan had been too deferential to the party bosses. "Don't use the word 'conservative'," he told Buchanan. "It doesn't mean anything any more."

Buchanan faded and so did Francis, who spent a lot of time denying that he was a white supremacist – even as he campaigned against interracial sex, warned of what he called "incipient race war", and drafted a nationalist manifesto which argued: "The American people and government should remain European in their composition and character."

Fast-forward to the 2016 primaries. Trump declares: "I'm a conservative, but at this point, who cares?" At the same time, he makes a series of provocative speeches, which were read as deliberate stirrings of anti-immigrant and anti-Muslim sentiment; and he rolls out anti-immigrant and isolationist policies.

Earlier this year, right-wing radio-talk heavyweight Rush Limbaugh joined the dots while reading some of Francis' articles on-air. "What's interesting is how right-on it is in foretelling Trump."

The bad news for Trump is that the general election is not the same as the primaries and support for him, even among white men, is falling. Clinton seems to have closed the gender gap – she's ahead 43-42 in one poll of white men, she has cut Trump's lead back to just a few points in another.

Trump has made the white male vote so crucial in 2016 that Brookings Institution demographer William Frey is running through election simulations based on every possible level of white male turnout on election day – and by his reckoning, even a virtual full turnout by non-college educated white guys, Clinton would win the popular vote by just over a million votes.

Based on Frey's number crunching and opinions polls as they now stand, it seems Trump's race-based gamble is not paying off – as the electorate becomes more diverse, whites are a smaller portion of the whole, down from 88 per cent in 1980 to 72 per cent in 2012.

What a pity then that he has been so crude and cruel to Hispanics and Muslims, so tin-eared with African-Americans. He claims to be a great businessman, but it seems Donald Trump can't count.