The dominant understanding of how motivations to contribute to public goods are generated and sustained is largely shaped by the combined action of rational choice theory and neoclassical economics. This understanding relies on three key assumptions: individualism, instrumentalism and market equilibration. This paper questions the theoretical consistency and empirical relevance of these assumptions and of their associated policy model. I argue that a significant revision of this motivational theory is needed, one that takes into account intrinsic incentives, trust and strong reciprocity, as well as the effect of social and institutional context, monetization and market interactions on the propensity to contribute to public goods. The paper concludes by outlining the implications of this theoretical reconsideration for the organization of scientific research and for more effective policy-making to sustain public goods provision.