One of the great mistakes, I think, of economics is it fails to understand that what something is, whether it’s retirement, unemployment, cost, is a function, not only of its amount, but also its meaning.

So where economists make the fundamental mistake is they think that money is money. Actually my pain experienced in paying five pounds is not just proportionate to the amount, but where I think that money is going. And I think understanding that could revolutionize tax policy. It could revolutionize the public services. It could really change things quite significantly.

Rory Sutherland, via TED