Selfishness is one of those issues where economists seem to see the world differently. It is not that economists are incapable of imagining - or even modelling - altruism. They can, but they usually don’t. And there is a good reason for that: people aren’t selfless.

The Johns Hopkins Comparative Nonprofit Sector Project estimates that charitable giving in the US was 1.85 per cent of the size of the economy in recent years, 0.84 per cent in the UK, and as little as 0.13 per cent in Germany. By this reckoning Germans are 99.87 per cent selfish and even Americans are more than 98 per cent selfish. That’s not 100 per cent but it is pretty close.

Admittedly, if you include the time spent volunteering, you can get selfishness rates as low as 95 per cent: step forward, the Dutch. That’s still not impressive. It is also an underestimate of selfish motivations. If people really were altruistic, the contribution of volunteering wouldn’t be nearly as high as it is.

This isn’t some silly tautology. If these do-gooders really were motivated by the desire to do good, they would be doing something different. It would almost always be more effective to volunteer less, work overtime, and give more. A Dutch banker can pay for a lot of soup kitchen chefs and servers, but that wouldn’t provide the same feel-good buzz, would it?

In fact, the closer you look at charitable giving, the less charitable it appears to be. A recent experiment by John List, an economist at the University of Chicago, and a team of colleagues, showed that donations are less than charitable after all. Using controlled trials to compare different methods of door-to-door fundraising, Professor List’s team discovered that it was much more effective to raise funds by selling lottery tickets than by asking for money. This hardly suggests a world populated by altruists seeking to do the maximum good with their charitable cash.

More effective still was simply to make sure that the fundraisers were attractive white girls rather than a dowdier assortment of male and female fundraisers representing all shapes, races and sizes. This dramatically increased the average contribution, because many more men decided to give some money. Altruism?

Few economists are surprised by these results. Robert Frank, from Cornell, wryly observes that those organising fundraising drives for the vast US charity United Way tend to be disproportionately estate agents, insurance brokers, car dealers and other people with something to sell. Many people buy charity Christmas cards, in effect giving to charity and then posting the receipts to their friends and colleagues.

Even the way we choose to dole out cash betrays our true motives. Someone with ₤50 to give away and a world full of worthy causes should choose the worthiest and write the cheque. We don’t. Instead, we give ₤2 to the street collector for Save the Children, pledge ₤15 to Comic Relief, another ₤15 to Aids research, and so on. But ₤15 is not going to find a cure for Aids. Either it is the best cause and deserves the entire ₤50, or it is not and some other cause does. The scattergun approach simply proves that we’re more interested in feeling good than doing good.

None of this is to say that these contributions are worthless nor economically insignificant. Just don’t get too starry-eyed about the motives behind them.

There is one final twist in the tale. Professor Frank and his co-authors decided to find out whether economists are stingier than non-economists. Frank’s team mailed questionnaires to university professors and discovered that the economists were more than twice as likely as the rest to give nothing at all to charity. At least they are honest.