For a man with the unlikely description of “rock-star economist”, there is nothing rock’n’roll about Thomas Piketty’s cramped, book-lined office in a nondescript Parisian office block. By his feet are scattered various foreign translations of his publishing sensation, Capital in the Twenty-First Century: Greek, German, Japanese, and so on. There are 20 foreign editions already published, he tells me with evident pride, and another 37 to come. It must be rather surreal, I suggest: one doesn’t normally expect a French economist to become a global superstar. “Is there something particular with being French, or economists in general?” he jokes in a thick Parisian accent, effecting a faux wounded Gallic pride.

Piketty’s book is surely the most influential published by an economist in a generation, infuriating the right as much as it delighted an intellectually starved left. Using a mass of data, the book sought to expose why modern capitalism is an engine of exploding inequality: the rate of return on capital exceeds the rate at which the economy grows, he argues, and wealth is becoming ever more concentrated at the top of society.

More explosively, he proposes a global wealth tax as a check on this process, even though he has conceded this is “utopian”. He has been feted by political leaders across the western world – Ed Miliband among them – and beyond. I ask the boyish 43-year-old if his life has been thrown upside down. “Not so much. Sure, it was much more successful than I could expect – it was a gradual process, I had time to get accustomed ... it’s not like a huge shock from complete anonymity to complete stardom. I’m still a little star!”

Piketty has been engaged in his research for 15 years. At the height of the global financial crisis in 2009, newly elected US president Barack Obama used the graphs of the economist and his team, upsetting Republican thinktanks, which complained that “these French economists were influencing the politics in the US”.

Still, it is quite an ascent for a man from relatively humble origins in a north Paris suburb. His mother, from a strongly working-class background, became a primary school teacher; his father, a technician at a research institute, was from a rich “bourgeois” family, “but decided to leave his family, in many ways”. Both were fleetingly involved in French Trotskyist group Lutte Ouvrière, but “they left very quickly because in Lutte Ouvrière you can’t really have a life”.

It is a source of deep satisfaction that his mother completed reading his book, and proof for him that he has achieved the accessibility he clearly craves. “She never reads big academic books, but she read it, and I think she understood everything ... I think it shows that it’s not true that issues of income and wealth and inequality and capital are too complicated. I think economists try to pretend it’s too complicated, and use very complicated mathematical models just to look scientific and try to impress other people.”

Thomas Piketty’s bestseller

Piketty’s 696-page book may be a bestseller, but are many people reading all of it? This is a sensitive question to put to any author, but I refer to analysis in the Wall Street Journal that – based on the fact that the five most highlighted passages on the book’s Kindle version are in the first 26 pages – an average of 2.4% of the book has been read. “It was a stupid statistic,” he says. “I think the people who have done that, they should read more books. I think it’s useful to read books, rather than doing this stupid statistic – this is really ridiculous. All that says is the introduction of my book is very good so people like it a lot and so they scribbled a lot on the introduction, but it doesn’t say anything about the fact that people have read it ... I think it’s really a readable book, it takes time to read, but I think it’s useful to read books – there’s nothing I can do for people who don’t read books, that’s beyond my power.”

The book came under ferocious fire from Financial Times journalist Chris Giles (although that critique was itself strongly criticised), who accused Piketty of errors. Did it ever make him nervous? “Not really, everything is online, everything has been online for ever, and I’m very happy they checked it,” he says, carefully sticking to a diplomatic line he has maintained since Giles’s opening salvo. But he can’t resist mocking the FT’s mixed messages. “People at the FT seem to be very confused. First, they say it’s full of mistakes and then they give me the best book of the year ... I responded to every point online. I think everyone who has looked at this has concluded that they made a lot of noise out of nothing at all. If it was full of mistakes, why did they give me their best book of the year?”

Piketty joined the elite École Normale Supérieure in Paris in September 1989, soon after which two big events had a profound impact on his political development. The Berlin Wall fell, leading him to travel to Romania and across eastern Europe. “I was born too late to have any temptation with communism, or at least Soviet-type communism,” he explains. “Travelling in eastern Europe and the ex-Soviet Union, you clearly don’t want to defend a system that would have empty shops and a totalitarian regime and internal passports.” The end of the cold war, for him, had two key intellectual consequences. “It’s easier for my generation to reopen the issue of inequality dynamics under capitalism, because I take for granted that private property is part of the solution,” he suggests. But although he believes the fall of Stalinism was “very positive”, it resulted in “very big power to capital, and a sort of faith in property rights, and the idea that free-market competition is going to get us to the ideal world, that there’s no need for redistribution, there’s no need for public regulation”. In other words, Piketty is part of an intellectual backlash to the rampant free-market triumphalism that was unleashed after the fall of the Soviet bloc.

The other influence is perhaps more surprising: the first Gulf war that followed Ba’athist Iraq’s invasion of Kuwait in 1990, which shocked him and his colleagues at the école. “It was a very strong event, because sometimes we say that governments cannot do much against tax havens, they’re too powerful. And suddenly we’re able to send 1 million troops 1,000km away from home to give back the oil to the emir of Kuwait. I was not sure this was the right redistribution of wealth.”

The west’s general relationship with the Middle East – “the most unequal region in the world”, he says – is one that troubles him, not least because it exposes grotesque inequalities. “Take Egypt: the total budget for education for 100 million people is 100 times less than the oil revenue for a few dozen people in Qatar. And then in London and in Paris we are happy to have these people buying football clubs and buying apartments, and then we are surprised that the youths in the Middle East don’t take very seriously our democracy and social justice.”

Not as radical as he is portrayed? Thomas Piketty. Photograph: Graeme Robertson

Although some on the right have assailed him as a dangerous red, I put it to him that he is not as radical as he is portrayed. He has written that he was “vaccinated for life against the conventional but lazy rhetoric of anti-capitalism”; he opposed the introduction of a 35-hour week in France, and the Wall Street Journal even called him “a neoliberal economist who sees many virtues in market forces but favours government redistribution to smooth out some of the market’s excesses.” He looks bemused. “I don’t live in the cold war. Some people maybe still live in the cold war, but this is their problem, not mine.” He unashamedly believes in “market forces”, arguing there is no “war of religion” between left and right in the modern era. But he defends his radicalism, arguing that a global wealth tax makes “property temporary, rather than permanent”, which he describes as “a permanent revolution, a very substantial change to the traditional capitalist system”.

Though Piketty supported François Hollande’s presidential bid in 2012, he is contemptuous of the French president. “He’s been a disaster,” is his unequivocal response, clarifying that he was “more against Sarkozy than [he] was for Hollande”. He assails the likes of France and Germany for their “selfish” attitude to austerity-ravaged southern Europe, and calls for the creation of a eurozone parliament based on majority decision-making – abolishing any veto – as the way forward. That would put a stop to beggar-thy-neighbour-type policies by countries such as Luxembourg that try to “steal the tax base of their neighbours”. That said, he rebukes what he describes as “the new extreme left movements” in Europe, specifically Podemos in Spain and Syriza in Greece.

Culture looms large among influences. The 19th-century French author Honoré de Balzac is among them. Piketty speaks of Vautrin, a “very cynical character” in one of Balzac’s novels, who asks an ambitious Parisian law student named Rastignac whether “he can get rich just by being a good student or whether he should marry someone with high wealth”. Another book that impressed him was Destiny and Desire, by the Mexican novelist Carlos Fuentes, which was full of insights into the “transmission of wealth in Mexico”. Both fed Piketty’s passionate interest in the “relative importance of wealth and labour in life”. He goes to the cinema up to four times a week, and his favourite movie of the year was Snowpiercer, a dystopian Korean film about a world destroyed by a botched attempt to curb global warming that leaves the remnants of humanity trapped on a train with the poor consigned to the very back, the very rich at the front.

There is an uncomfortable topic that I have to raise. Earlier this year, allegations surfaced that Piketty had perpetrated domestic violence against his former partner, who made a legal complaint in 2009. Piketty has spoken out before to confirm he was arrested but that no charges or prosecution followed. His response, however, at this interview, is perturbing. When I ask about the allegations, he clams up and begins to mumble. “I’ve not seen that, you’re the first person to tell me about it.” It has been in several newspapers, I say (he denied doing anything wrong at the time). “I’ve not seen it.” The claims are just all nonsense, then? “I have not seen it. I am sorry. You probably don’t read the same papers as I do!” A nervous laugh follows.

I move on, although the atmosphere has gone rather stale. Does he find his rock-star intellectual reputation demeaning or has he embraced it? “Well, if it gets more people to read my book, then I have no problem with the publicity,” is the curt reply. His aim is to allow people to make up their own minds. Explaining his success, he argues that “what I’m really contributing to in this book is a democratisation of economic knowledge”. His aim is not to “have breakfast or lunch with politicians” – though he does out of politeness, he says, with Ed Miliband or Chile’s president, Michelle Bachelet – but to try to win over public opinion, which he thinks is a more effective means of pressuring the political elite. His book has already prompted governments to release more of their fiscal files to help further studies into the distribution of wealth.

Piketty fears the far right, including the surging National Front in France, which he describes as “very frightening”. “I am afraid that if you don’t find peaceful domestic solutions to our inequality and social problems, then it’s always tempting to find other people responsible for our problems.” The social contract is threatened by middle-class and poor people resenting paying more tax than multinational companies, which sometimes pay nothing. But he has optimism, too. He believes public opinion in Europe remains “strongly attached to certain forms of social models”. The continent remains more egalitarian than the US, and politics not quite as hijacked by Big Money.

But for Piketty, revolution is not the solution. “I think one problem in the past is that people put more energy into thinking about the day of the revolution itself than what they’d do in power,” he says. More historical shocks – like war and revolution – will undoubtedly come, he believes. “But at the same time, if I have chosen to write books rather than to be a guerrilla or something like that, it’s because I believe democratic discussion and drawing from history can get us to do better next time. A peaceful solution.”