There is still a sense of incongruity about the sight of people protesting against greed on the streets of New York. Isn't America supposed to be the one country where making it big is celebrated and where falling by the wayside, is, well, one of those things?

But as a spreading protest movement in New York, Boston and other cities has shown, Americans' traditional deference towards unbridled capitalism can no longer be taken for granted. Many Americans clearly now feel there is something fundamentally wrong with the way their society is heading, and are questioning an economic system that no longer seems to distribute its fruits equally across a broad swathe of society.

It is no accident that many of the protesters in New York, like those over the summer in European capitals, are young, middle-class children. These are the disappointed offspring of parents who took for granted that if you got a decent degree and paid your taxes, what you got back was a guaranteed good life, however modestly interpreted: a steady job, a home, a pension at the end. Now the old social contract doesn't apply.

Some have complained that the New York protesters lack a clear agenda. They are against greed and "Wall Street", but what do they want? The same criticism was made of the thousands of young people who occupied the Puerta del Sol, near Madrid, this summer.

The truth is that we live in an age of ideological as well as economic uncertainty, and in which confidence has declined in the efficacy of any of the old slogans, whether of left or right. The New York protesters feel frustrated with what they see around them and that's about it. To that extent, the city is following a pattern set in Madrid, Athens, Cairo and elsewhere. For once, New York is following, rather than taking, a lead.