When I was a small child I thought that the Vietnam War was taking place in a car park.

Every time I watched the news, I heard reporters talking sombrely of that conflict, accompanied by pictures of violent encounters. Some of the soldiers wore uniforms and charged on horses, others were clothed in denim. It wasn't clear who was winning, but I remember the smoke and the chaos, and a young man lying across a car bonnet being hit with a club. The young man was carrying a poster on a stick, which even to my infant mind seemed an odd thing to carry into a warzone.

Ever since I grew up enough to understand this error, I have been amused by my childish naivety - confusing the Vietnam War with the protests, indeed! But at the weekend, reading Tariq Ali's account of the events of 1968 (“It turned violent. Like the Vietnamese, we wanted to occupy the embassy”) I realised that what I had displayed all those years ago was not naivety it all. It was a precocious talent for political analysis.

The 1968 protests are not best understood as their instigators would have them understood - as the antithesis of war, as the street carnivals of the peace movement. The protesters should instead be seen as having some similarities with the warriors they were opposing. Both were trying to solve a problem with violence. The protesters sought to resolve political conflict in the street and through confrontation. Many of the leaders were not wishing for an end to war, but for victory by the North Vietnamese. In my confusion between the protests and the war I had accidentally seen things clearly.

Now I am not trying to make a point about who was right and who was wrong, who had the bigger weapons and who did the killing. Instead, I am trying to rescue the protests of 1968 from the romantic memories of the participants. I hope in this way to try to show why they are still relevant.

Every attempt to revisit 1968 majors in ideology. Tariq Ali talks of sexual revolution, the liberal author Paul Berman writes of the democratic ideal and the struggle against fascism, the French intellectual Bernard-Henri Lévy sees the common thread between the fight for liberation against Western oppression and the Prague Spring. Meanwhile, the playwright Tom Stoppard found little of any value. He thought the whole thing was merely embarrassing.

I am with Stoppard. This is not, however, just because I think the slogans of the soixante-huitards silly and their flirtation with communism disgusting. It is because I believe all attempts to explain 1968 in terms of ideas are doomed to failure. The events of 1968 were not about ideology, but demographics.

Consider this - a favourite fact that I have rehearsed here before. Young Americans were the group most in favour of the Vietnam War, according to contemporary opinion polls. This remained the case even when the war became unpopular. Here's another fact - young people in this country are the group most in favour of the Iraq war. If you see the events of 1968 as ideological, this opinion poll data is hard to understand. Why aren't young people more idealistic and pacifistic than others? And if they aren't, why wasn't Grosvenor Square packed with rioting old age pensioners?

However, if you see the événements as the product of demographics, the data is easy to comprehend. Young people, particularly young men, tend to see violent solutions to problems as more acceptable than do other groups in society. In 1968 there was a bulge in the number of hot-headed young males.

Some of them chose protest violence on the streets of Europe, others riots in America's ghettos or dissent in Eastern Europe, while still others supported foreign wars. They were united not by ideas but simply by youth. Tariq Ali appears bewildered that the anti-Iraq war movement hasn't evolved into something similar to the soixante- huitards. This isn't because idealism has died. It is because there is no youth bulge. And it is the youth bulge, not anything they said or did, that gives a reason for the 1968 riots to be remembered.

Violent conflict in 17th-century England, the French Revolution, German nationalism in the First World War, the 1979 Iranian revolution, the Cultural Revolution in China and most 20th-century revolutions in developing countries took place where large youth bulges were present. And academic studies suggest that the number of deaths in armed conflict is much higher in countries with a large youth bulge, even when controlling for income and inequality. Between 1989 and 1993, violence in the former Soviet republics varied with the size of their young male population, even where the initial political conditions were similar.

The social scientist Gunnar Heinsohn in his book Sons and World Power argues that when 15 to 29-year-olds make up more than 30 per cent of the population, there is a good chance that violence will follow. There are 67 countries in the world where there is such a bulge and there is violence in 60 of them. He cites the Palestinian territories and Afghanistan as examples and contrasts them with, say, Tunisia or even the passing of the youth peak in Lebanon.

With our blithe conviction that we can always make things better, we are convinced that political education and economic amelioration will work to bring peace where there is conflict. Heinsohn suggests that it might make things worse. Educated and well-fed young males tend to greater violent unrest.

The only hope? That young men eventually grow up. In Northern Ireland, the vast majority of victims and perpetators were young men. But one day Gerry Adams decided he was getting too old to strap on a gun. And the rest is history. Our only alternative in, say, fighting al-Qaeda may be to hold firm and wait it out.

The real lesson of the 1960s isn't Turn On, Tune In, Drop Out. It is Press On, Calm Down, Grow Up.

daniel.finkelstein@thetimes.co.uk

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