RESEARCH ARTICLE Dilemma of Dilemmas: How Collective and Individual Perspectives Can Clarify the Size Dilemma in Voluntary Linear Public Goods Dilemmas

Empirical findings on public goods dilemmas indicate an unresolved dilemma: that increas-ing size—the number of people in the dilemma—sometimes increases, decreases, or does not influence cooperation. We clarify this dilemma by first classifying public goods dilemma properties that specify individual outcomes as individual properties (e.g., Marginal Per Cap-ita Return) and group outcomes as group properties (e.g., public good multiplier), mathe-matically showing how only one set of properties can remain constant as the dilemma size increases. Underpinning decision-making regarding individual and group properties, we propose that individuals are motivated by both individual and group preferences based on a theory of collective rationality. We use Van Lange's integrated model of social value orienta-tions to operationalize these preferences as an amalgamation of outcomes for self, out-comes for others, and equality of outcomes. Based on this model, we then predict how the public good's benefit and size, combined with controlling individual versus group properties, produce different levels of cooperation in public goods dilemmas. A two (low vs. high bene-fit) by three (2-person baseline vs. 5-person holding constant individual properties vs. 5-per