An axiomatic approach to the measurement of inequality of opportunity

We formulate three sets of axioms to measure inequality of opportunity. First, the basic axioms that any relative measure should satisfy. Second, axioms that capture the ex ante perspective, focusing on inequality between individuals with different circumstances. Third, axioms that capture the ex post perspective, focusing on inequality among individuals with the same responsibility characteristics. Based on these axioms, we characterize the ex ante and ex post classes of inequality of opportunity measures. We also discuss how well existing measures in the literature adhere to the axioms.