This paper presents Amartya Sen's challenge to popular liberal egalitarian theories (utilitarianism, well–being, and John Rawls' "primary goods"). It explores the alternative posed by Sen and Martha Nussbaum to those Theories: the capability approach. The challenge is twofold: the first revealing that the indicators used by said theories (a) do not yield the measured outputs required for assessments and comparisons, and (b) imply inconsistencies within their respective systems. The second, theoretic, challenge, argues that these theories fail to address what is needed, namely, how outputs actually affect agents. The paper thus presents the 'Capability Approach,' commenting on the differences between Sen and Nussbaum regarding what the latter calls 'Basic Entitlements', and on what freedom means. This account is preceded by Sen's argument against absolutist models of Justice.