The paper makes a contribution to "the new economics of science" in that it argues that science is not a pure public good, as is often believed, but is, rather, a contribution good. Pure public goods are both non-excludable and non-rival. A contribution good, in contrast, is like a club good in that it is non-rivalrous but at least partly excludable. The excludability is due to the fact that not everyone is a member of the "club". To be a member of the "club" you have to be able to understand the science at issue. Also consumption is tied to contribution. If you want to be able to make use of the science you need to have mastered the underlying material which normally means you have to be trained as a scientist - you are a member of the "club". This in turns means you will be contributing to the subject.
The important problem here is not, as is the case for public goods, that of free riding but rather being able to create a critical mass of scientists. The club must be of a size large enough to generate both private and social gains.
The abstract reads
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.