Consequentialism and Collective Action

Consequentialists have a standard response to collective action problems like climate change mitigation and voting. You ought to do your part, they say, because (i) all such problems are triggering cases, in which there is a threshold number of people such that the outcome would be worse if at least that many people acted in a given way than if fewer did, and (ii) doing your part in a triggering case maximizes expected value. I show that both claims are false, for reasons previously unnoticed: Some triggering cases cannot be solved by appeal to expected value, since they involve infinities, and some collective action problems are not triggering cases, since they involve parity. I then show that consequentialists can give principled responses to both problems, first by moderating their ambitions and aiming to solve only realistic collective action problems, and second by adopting Prospectism as a theory of decision-making under parity.