Modelling science as a contribution good

The non-rivalness of scientific knowledge has traditionally underpinned its status as a public good. In contrast we model science as a contribution game in which spillovers differentially benefit contributors over non-contributors. This turns the game of science from a prisoner's dilemma into a game of 'pure coordination', and from a 'public good' into a 'contribution good'. It redirects attention from the 'free riding' problem to the 'critical mass' problem. The 'contribution good' specification suggests several areas for further research in the new economics of science and provides a modified analytical framework for approaching public policy.