Overexploitation of renewable resources today has a high cost on the welfare of future generations1, 2, 3, 4, 5. Unlike in other public goods games6, 7, 8, 9, however, future generations cannot reciprocate actions made today. What mechanisms can maintain cooperation with the future? To answer this question, we devise a new experimental paradigm, the ‘Intergenerational Goods Game’. A line-up of successive groups (generations) can each either extract a resource to exhaustion or leave something for the next group. Exhausting the resource maximizes the payoff for the present generation, but leaves all future generations empty-handed. Here we show that the resource is almost always destroyed if extraction decisions are made individually. This failure to cooperate with the future is driven primarily by a minority of individuals who extract far more than what is sustainable. In contrast, when extractions are democratically decided by vote, the resource is consistently sustained. Voting10, 11, 12, 13, 14, 15 is effective for two reasons. First, it allows a majority of cooperators to restrain defectors. Second, it reassures conditional cooperators16 that their efforts are not futile. Voting, however, only promotes sustainability if it is binding for all involved. Our results have implications for policy interventions designed to sustain intergenerational public goods.
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Extended data figures and tables
Extended Data Figures
- Extended Data Figure 1: Bootstrapping simulations demonstrate the robustness of full voting and the failure of partial voting. (275 KB)
We address sources of noise in the sequence of events that occurred in our experiment by conducting a set of computer simulations using the data generated by our participants. We randomly sample (with replacement) a series of generations of participant decisions, and calculate the fraction of those generations in which the pool was refilled. For each condition, we simulate 10,000 pools (or 1,000,000 pools if δ < 0.8) for 15 generations. a, Simulated data for the unregulated, full voting and partial voting conditions show that full voting is by far the most successful at sustaining the pool. b, Simulated data for the T = 40%, T = 30%, δ = 0.7 and δ = 0.6 conditions shows that reducing δ has only a small effect, and although reducing T does undermine sustainability, the effect is much less striking than that of unregulated or partial voting despite the higher value of T in these less-regulated conditions.
- Extended Data Figure 2: Countries with more democratic governments have more sustainable energy policies. (182 KB)
Energy sustainability index (as measured by the World Energy organization) is shown as a function of the democracy index (as measured by The Economist Intelligence Unit) for n = 128 countries. A strong positive association is clearly visible, and this association is robust to controlling for gross domestic product (GDP), Gini index, population size, literacy rate, unemployment rate, life expectancy and level of corruption. Thus we provide preliminary empirical support for the role of democracy in promoting sustainability outside the laboratory. We adopt the colouring and naming scheme from The Economist Intelligence Unit’s classification of regimes.
- Supplementary Information (2.7 MB)
This file contains Supplementary Text and Data, which includes Supplementary Methods, Supplementary Tables 1-7 and additional references.