Johann Hari: Clint Eastwood shows how America is changing

In the endless babbling torrent of news, it's easy to miss the small signs of how a culture – and a country – changes. For me, a marker almost as sweet as a black man in the White House has just flickered into Britain's cinemas.

Clint Eastwood is the quintessential icon of the old America: an icy Everyman who made his fame cursing liberals, shooting down suspects, and slaying Injuns on screen. But now, in his eighth decade, Eastwood has done something remarkable. He has been making beautiful, understated movies that apologise for the filth he pumped out early in his career – and propagandise for a very different America. Yes: Dirty Harry has turned pinko-peacenik.

Eastwood strutted into the American consciousness in the 1950s in the TV series Rawhide and a string of big-screen Westerns. He caught the tail-end of the uncomplicated Us vs Them cowboy flicks where the Indians were evil, scalping savages who had to be destroyed by the white heroes. The films were gorgeous, romantic accounts of a genocide, told adoringly from the perspective of the genocidaires. The attitude of the genre was typified by John Wayne's jeer: "I don't feel we did wrong in taking this great country away from them... the Indians were selfishly trying to keep it for themselves."

But Eastwood found his most iconic role as a new kind of urban cowboy. In the 1971 film Dirty Harry, he plays Inspector Harry Callahan. It was the first of the wave of backlash movies, explicitly taking on the Sixties counter-culture and accusing it of destroying America. The plot focuses on a serial killer called Scorpio, who is a pansy-parody of the peace movement: a long-haired, androgynous, lisping hippie who wears the peace logo. He shoots random civilians, and says he will only stop if he is paid a ransom of $100,000.

Dirty Harry is an old-style cop, fond of beating and torturing confessions out of suspects. He summarises his approach by saying: "I shoot the bastard, that's my policy." His colleagues boast that Harry "is an equal opportunities hater – spicks, niggers, kikes, dagoes – especially spicks." He sets out to catch the killer – but at every turn he is emasculated by insane liberal regulations. The new laws prevent him from breaking into homes without a warrant, committing torture, or harassing suspects. Appalled, Harry spits: "That man has rights? The law is crazy!"

As a result of the evil liberals fettering Harry, Scorpio is left free to suffocate a 14-year-old girl and hijack a schoolbus full of kids. In the end, Harry shoots Scorpio in cold blood and throws his police badge away in disgust. Pauline Kael, the greatest film critic of her time (or any time), famously called the film "fascist." Dirty Harry's motto – "Go ahead, punk. Make my day" – became a classic.

But then something odd happened. The old black-and-white world of Dirty Harry bled away – and a subtle, supple film-maker emerged in his place. There were hints of a change in Unforgiven, his 1992 Western. Suddenly, the old gun-slinger at the centre of the film – played by Eastwood – was broken and traumatised by the sadism he had inflicted in his earlier life. We no longer yelled for him to kill more: we felt uncomfortable, and ambiguous.

Since then, Eastwood's films have been populated with people broken by the kind of casual violence inflicted to such noisy cheers by Dirty Harry. The Changeling is the true story of what happens when the police disobey the rules and embark on torture and violence to achieve their goals – told from the perspective of the victim. The Flags of Our Fathers is the true story of the soldiers who raised the US flag on Iwo Jima during the Second World War – and how the Native American soldier there, Ira Hayes, returned to face internal apartheid and abuse. The companion-film, Letters From Iwo Jima, is even more bold, telling the story of the war from the other side – that of the Japanese soldiers. Eastwood began to be attacked by the likes of Rush Limbaugh for becoming "liberal".

But with his latest film, Gran Torino, Eastwood makes his repentance explicit. He plays Walt Kowalski, a cussed old widow and Korean war vet living alone in a neighbourhood that is increasingly populated by immigrants. Walt could be Harry Callahan in retirement: he curses the "babbling gooks" who move in next door and clings to his fat guns.

But one day, Walt sees a gang attacking his Hmong-immigrant neighbours, as they stumble on to his lawn – and he scares them off with a gun. The Hmong family begin to shower him with gifts and affection, as the gang circles every closer. It becomes clear that Walt is broken by the violence he committed more than fifty years ago in Korea. "You want to know what it's like to kill a man?" he asks. "It's gooddam awful and the only thing worse is being given a medal of honour for killing a guy who just wants to live."

Yet it becomes clear that Walt will fight back against the gang to defend his neighbours – and it seems like progress from Dirty Harry, but not much. Yes, liberal vigilantism is better than illiberal vigilantism, but only by inches.

But then the film surprises you – and shows how far Eastwood has really come. (If you don't want to know the ending of the film, skip this paragraph.) He goes to confront the gang, and we expect a gleeful shoot-out. But the gang are waiting for him, armed like a militia. Walt watches them slowly, sadly, and reaches into his jacket. As he does, he dares the gang to shoot him first. "Go ahead," he says – deliberately echoing Dirty Harry. They fill him with lead, there, in the street. But it turns out Walt was unarmed – and now the gang is going down for life. His neighbours are free at last. The echo of the old catch-phrase is ironic: Eastwood's smiling form of apology. The first time the actor said "Go ahead" on the big screen, he was sacrificing the law with violence to attack liberals. This time, he was using the law and non-violence, to defend immigrants.

In an age of forced apologies, here is a real one. This shift in one of America's greatest icons is – I think – a helpful, hopeful sign of the wider shift in American culture. Although it was obscured by the back-lash jolts of 9/11 and the Bush years, the US has been slowly becoming a more liberal and open-minded society. Look at the difference between the reaction to the My Lai massacre in Vietnam and the Abu Graib horror in Iraq. When My Lai broke – the deliberate massacre of a whole village, including children – 40 per cent of Americans defended it, and songs celebrating it topped the charts. When Abu Ghraib broke, only the madder fringes of talk radio praised it; more than 90 per cent were repulsed.

The old Dirty Harry racism and brutality is abating, as the country's great civil rights movements slowly win. Of course, that doesn't mean the actions of the government will necessarily follow Walt and public opinion. They are often driven by forces that aren't as accountable to democratic pressure, like corporate power, or the super-rich – but in time, they too can be eroded. If Inspector Harry Callahan can say sorry and change, anyone can.

Go ahead, America – make our day.

j.hari@independent.co.uk