America is run by the rich and powerful in their own interest. To an extent that I think is hard to exaggerate, the intellectuals - academics, journalists and so on - are bought off. And that's a big change that happened in the United States in the last 30 or 40 years.

Over the period from 1988 to 2005, the income share of the top five percent has grown by about 3.5 percent of global household income, and the shares of all the other groups have diminished. The greatest relative reduction was in the bottom quarter, which lost about one third of its share of global household income, declining from 1.155 to 0.775 percent, and now is even more marginalized.

The collective income of all these people - the bottom half - is less than three percent of global household income, and so there is a grotesque maldistribution of income and wealth.

Social rules are susceptible to moral analysis. This is, again, relatively familiar in the domestic case, where we now condemn slavery as unjust. And when we affirm this judgment, we're not merely saying that all those people who owned slaves were unethical people; they shouldn't have done that. We do believe this, but that's only part of the point. We also believe that the fugitive slave laws were unjust.

What we should do is require or at least permit innovators to license their green innovations free of charge in exchange for public payments based on the impact this innovation has on the environment - emissions averted or something of this sort.

If the Health Impact Fund were to be instituted, a single company would be in charge of a medical product all the way from its conception to the health improvements realized by actual patients. The company would be paid for health impact, and it would have to arrange the entire pipeline in between - all the steps of invention, of clinical testing, of getting marketing approval in many different countries, of wholesalers and retailers and prescriptions and so on - in a holistically optimal way.

In 88 poor countries for which we have data, in each and every one of the 88, the PPP for food shows that poor people can buy less food than you would expect from the PPP that the World Bank is using. The reason for this is obvious on reflection. It has to do with the fact that most foodstuffs are tradable commodities: basic foodstuffs, such as rice, flour and beans, can easily be conveyed across national borders and their prices will therefore roughly mirror the exchange rates among currencies.