Each of three people chooses whether or not to contribute a fixed amount towards the provision of a public good. The good is provided if, and only if, at least one person contributes; if it is not provided, then the contributions are not refunded. Each person ranks the outcomes from best to worst as follows:

(i) Any outcome in which the good is provided and he/ she does not contribute. (ii) Any outcome in which the good is provided and he/she contributes. (iii) Any outcome in which the good is not provided and he/she does not con- tribute. (iv) Any outcome in which the good is not provided and he/she contributes. This situation could be formulated as the following three-player matrix game: C N C N C 2,2,2 2,3,2 C 2,2,3 0,1,1 3,2,2 1,1,0 Z 1,0,1 1,1,1 C N