Offering people incentives may backfire by undermining altruism, according to new research.

Offering people incentives may backfire by undermining altruism, according to new research.

People have put the princ iple of "enlightened self-interest" in different ways over the years, like the Scots philosopher David Hume: "Every man ought to be supposed to be a knave."

Or Adam Smith: "By pursuing his own interest (the individual) frequently promotes that of society more effectually than when he really intends to promote it."

But what if people aren't always knaves, asks Professor Sam Bowles from the Santa Fe Institute in New Mexico.

He argues today in the journal Science that economics will get it wrong, sometimes badly so. He points to new experimental evidence that people often act against their own self-interest in favour of the common good, and they do so in predictable, understandable ways.

Among the examples he cites are six day care centres which imposed a fine on parents who picked their children up late. The effect? Lateness doubled, and it stayed high even when the fine was removed.

"Parents, it seems, stopped seeing lateness as an imposition on teachers, and instead saw it as something that could be purchased with no moral failing," says Mr Bowles.