US inequality is at its highest point for nearly a century. Those at the top – no matter how you slice it – are enjoying a larger share of the national pie; the number below the poverty level is growing. The gap between those with the median income and those at the top is growing, too. The US used to think of itself as a middle-class country – but this is no longer true.

Economists have justified such disparities by citing “marginal productivity theory”, which explains higher incomes through greater societal contributions. But those who have really transformed our society, by providing the knowledge that underpins the advances in technology, earn a relative pittance. Just think of the inventors of the laser, the Turing machine or the discoverers of DNA. The innovation of those on Wall Street, while well compensated, brought the global economy to the brink of ruin; and these financial entrepreneurs walked off with mega-incomes.

One might feel better about inequality if there were a grain of truth in trickle-down economics. But the median income of Americans today is lower than it was a decade and a half ago; and the median income of a full-time male worker is lower than it was more than four decades ago. Meanwhile, those at the top have never had it so good.

Some argue that increased inequality is an inevitable byproduct of the market. False: several countries are reducing inequality while maintaining economic growth.

Read more at The Financial Times.