Pré-publication, Document de travail: What drives voters’ decisions to participate in large elections under costly voting, despite the rational expectation that this has no impact on the outcome? We propose a new model of ethical voters, by positing that they have Kantian or semi-Kantian preferences. With such preferences, voters evaluate their behavior in light of what the outcome would be, should a fraction of the other voters choose the same course of action. The “other voters” can be either the entire population (“non-partisan ethics”) or the individuals with same interest (“partisan ethics”). In a model with two candidates and a continuum of voters, we find that turnout is strictly positive as soon as the evaluation by the voters of the political outcome is not strictly of the “winner-take-all” kind. Moreover, the equilibrium turnout rates depend on the specifics of the election at hand, such as the relative stake of the election for the two supporter groups and the presence of core constituent groups.