Who is the most popular politician in the world? Probably the foul-mouthed, gun-toting septuagenarian president of the Philippines, Rodrigo Duterte. His most recent approval rating was 88 per cent, rising to 91 per cent among the poorest Filipinos. How does he do it? By indiscriminately rubbing out supposed bad guys – and if some of them do actually turn out to be criminals, so much the better. Insulting all and sundry seems to help too. He recently had a pop at God himself, who is a ‘stupid … son of a bitch’ in the president’s considered opinion. And all that in a country that remains deeply Catholic.

Duterte is the subject of Jonathan Miller’s new biography. A television reporter in Southeast Asia, Miller himself has been on the receiving end of some choice words from Duterte. Elected to the presidency in 2016, the former mayor of Davao and self-confessed murderer is a rich subject for a biographer; some have called him Trump’s inner demon. Miller covers the bases. But he leaves himself too little space in which to look properly at some of the more intriguing aspects of Duterte’s politics beyond the ferocious war on drugs, which undoubtedly defines his presidency.

The best part of the book is where Miller reveals how Duterte came to be so psychopathically awful in the first place. He was not, after all, from the street exactly. His father was governor of the vast province of Davao, on the island of Mindanao, and as Miller observes, the young Rodrigo was ‘probably the most privileged teenager in Mindanao; a spoiled brat, in many ways’. Yet his father was also away a lot, so Rodrigo was effectively brought up by his dad’s bodyguards, a notorious unit from which he learned the ‘ways of the street … the coarse fighting talk, values, and mannerisms of the paramilitary cops … he adopted the persona of a bugoy, the term for “hoodlum” in his local Bisaya language.’ It was there that a lifelong obsession with guns began. Learning how to be a gangster from the cops formed Duterte. However many people he kills or orders to be killed, he always sees himself as being on the side of the angels. He was also abused by a priest. Did the young Rodrigo gain some comfort amid all this brutality and emotional aggression from his beloved mother? Her nickname was ‘The Punisher’.

Miller has some fun with Trump comparisons. The American president is an unashamed admirer of the diminutive Filipino strongman; you often get the impression that Duterte does what Trump wishes he could do if he weren’t so constrained by all those maddening judges, laws and congressmen. In 1998, when Duterte was getting divorced, a clinical psychologist was called in to assess Duterte’s character as part of the legal process. Dr Dayan decided that the president-to-be was suffering from narcissistic personality disorder, which manifested itself in his ‘gross indifference, insensitivity, and self-centeredness, his grandiose sense of self and entitlement, his manipulative behaviors, his lies and deceits, as well as his pervasive tendency to demean, humiliate others and violate their rights and feelings.’ As others have pointed out, this could equally well describe Trump; in fact it’s almost a generic profile of the ruthless, authoritarian leader. Democracy will outlast Trump in America, but in developing countries like the Philippines, where the roots of democracy are shallower, the outcome is less certain.

Duterte’s shoot-to-kill style of politics, his utter disregard for human and civil rights, is inexcusable, but it might at least be understandable if it worked. It doesn’t, as Miller shows. For all the enthusiastic work of Duterte’s death squads in Davao when he was mayor, supposedly removing scum from the streets, crime statistics show that the city remains far from safe. Davao is the murder capital of the Philippines, with more than a thousand murders recorded between 2010 and 2015. Drugs are still rife, and the city is also ranked number two in the country for rape. There is no reason to think that the Philippines as a whole will turn out any differently. Violence, as has been shown again and again, merely begets more violence.

Much of Miller’s book zigzags through the killings and the drug wars. The narrative is sometimes confusing and often gets bogged down in detail. Only in the last chapter does Miller turn to Duterte’s other policies and prejudices, which may in the end turn out to have rather more bearing on the future of the Philippines than the mayhem in the streets. In particular, in spite of his bromance with Trump, he seems determined to strain his country’s crucial alliance with America as far as he can, maybe even to breaking point. For a country in the midst of a serious confrontation with China in the South China Sea, this looks foolish in the extreme, but the free-speaking president barely seems able to stop himself from evoking all the country’s latent anti-Americanism at every opportunity. Duterte’s attitude towards the Muslim insurgency in the south also deserves more space. He has been unusually sympathetic to demands for a semi-autonomous region there in the past, suggesting that he might be a smidgen more complex than he appears. But his storming of the city of Marawi, which had been captured by jihadists, implies that the president’s sympathies might have changed.

There are constant rumours that he is unwell. Probably only his early demise will spare the Philippines any more pointless deaths.