In a model where agents have unequal production skills and different preferences, we build social welfare functions which rely only on ordinal non-comparable information on individual preferences. Social welfare functions are required to satisfy properties of compensation for inequalities in skills, and responsibility for preferences. Then, assuming skills and preferences are unobservable, we use these social welfare functions to design optimal income tax schemes. We obtain ethical foundations for, among others, a maximized minimal income, a zero marginal tax rate for low incomes, and increasing marginal tax rates.