We study fairness in economies where humans consume one private good and one public good representing the welfare of other species. We show that a social evaluator cannot be egalitarian with respect to humans while always respecting humans' unanimous preferences. One solution is to respect unanimous preferences only when doing so does not lead to a decrease in the welfare of other species. Social preferences satisfying these properties reveal surprising connections between concerns for other species, egalitarianism among humans, and unanimity: the latter two imply a form of dictatorship from humans with the strongest preference for the welfare of other species.
Fleurbaey, Marc, and Martin Van der Linden.
"Fair Social Ordering, Egalitarianism, and Animal Welfare."
American Economic Journal: Microeconomics,
Consumer Economics: Theory
Equity, Justice, Inequality, and Other Normative Criteria and Measurement