Veil of Ignorance

“A method of determining the morality of a certain issue (e.g., slavery) based upon the following thought experiment: parties to the original position know nothing about the particular abilities, tastes, and positions individuals will have within a social order. When such parties are selecting the principles for distribution of rights, positions, and resources in the society in which they will live, the veil of ignorance prevents them from knowing who will receive a given distribution of rights, positions, and resources in that society.”

Gabriel Weinberg's Mental Models I Find Repeatedly Useful