Greener Than Thou: People who protect the environment are more cooperative, compete to be environmental, and benefit from reputation

Protecting the environment is a social dilemma: environmental protection benefits everyone but is individually costly. We propose that protecting the environment is similar to other types of cooperation, in that environmentalism functions as a signal of one’s willingness to cooperate with others. We test several novel predictions from this hypothesis. We used a mathematical model to show that environmentalism can indicate one’s valuation of others and thus one’s cooperative intent. We found support for this prediction in two online studies, and then conducted two laboratory studies to extend the idea that environmentalism signals one’s willingness to cooperate. Participants donated more to an environmental charity when donations were public than when anonymous, but they donated the most when competing to be chosen by an observer for a subsequent cooperative game. In other words, people competed to donate more to the environment. Bigger donors benefited, as they were subsequently chosen more often and received more cooperation from their partners. Partners benefited from choosing environmental donors: bigger donors cooperated more with subsequent partners, such that environmental donations were reliably informative about participants’ future cooperativeness. We compare multiple theories about why people behave environmentally (indirect reciprocity, signal of wealth, signal of cooperative intent), and find most support for our proposed theory of signaling cooperative intent. By understanding the function of environmental behaviour and stimulating competitive giving, we can increase people’s support for environmental and other charitable causes.