Luigi Taparelli, S.J. promoted the revival of scholasticism at the Collegio Romano in the 1820s, where the future Leo XIII was among his students. With his Theoretical Treatise on Natural Right Based on Fact, 1840–1843, he elaborated a natural-law approach to politics that became a hallmark of Catholic social doctrine. Among those whom Pius IX assigned to found the journal Civiltà Cattolica in 1850, Taparelli’s critiques of radical liberalism left him erroneously marked in public consciousness as an intransigent opponent to political liberalization in general. This reputation marginalized interest in Taparelli and obscured the relevance of his theoretical works to the development of the Catholic liberal tradition. Among other things, Taparelli elaborated the concepts of social justice and subsidiarity but with implications at times quite different from how these terms have been used historically.