Global public goods have benefits which go beyond the person or country that paid for them. For example, if a country invests in R&D for new scientific discoveries in health or agriculture, the benefits will be available to everyone, not just the country that paid for it. This characteristic of public goods means that there will usually be too little investment in them. A wide range of global public goods - from health R&D to preventing climate change - suffer from lack of investment. Wealthy countries generally invest too little in these, because the benefits go broadly, and so everybody has an incentive to free-ride on the investment of others.

Knowledge resulting from R&D is a particular type of global public good. One new knowledge has been discovered - about how to vaccinate against polio, or to improve crop yields by using a different type of seed - it is irrational for people to be excluded from using that information, which could save lives and increase prosperity for millions of people. But unless there is some restriction on who can use that knowledge once it is discovered, there will be no market return to investing in it.

This suggests that governments should find ways to increase funding of R&D. They could directly fund research by universities and public research institutions; they could fund public-private partnerships; and they could create economic incentives for private investment, for example by guaranteeing to buy new medicines if they are invented. The returns from this sort of expenditure are very high. There is less opportunity for corruption and waste than for some other forms of aid, and the benefits (in terms of advancement of human understanding) benefit rich countries and poor countries alike.