Abstract

This dissertation systematizes the thought of Pope Leo XIII in his social encyclicals, using the common good as our guiding point. Direction is taken throughout from the teaching of Thomas Aquinas. ;After discovering Leo XIII's understanding of the nature of a good, we develop his teaching concerning the goods proper to man. ;The good of the family is founded on marriage. As a natural law institution, marriage has a naturally sacred character; as a Christian sacrament, it also has a supernatural character. Given the depravity into which natural marriage has a tendency to fall, Leo XIII upholds Christian marriage as the only solution to safeguard the family and civil society. Cooperation between civil and ecclesial authorities, each having proper care for marriage, is to reflect that between faith and reason. ;Reason finds its perfection in truth. Assisted by faith, reason can be freed from error and rise to supernatural truths. Reason also leads man into the political order where he is guided by law, an ordinance of reason.Civil authorities can justify their legal compulsion of others only by founding human law on a superiorauthority: natural and eternal law. ;Legislators must aim at the common good. The political common good is shared by all the citizens. The common good is the order of the city, both in the sense of all the parts being in their proper places, and in the sense of these in-place parts exercising their proper virtue. The common good of the city is superior to the common good of the family, but is inferior to the common good of the Church. Like their cooperation concerning marriage, Leo XIII insists that harmony between ecclesial and civil authorities must prevail so that each can achieve its end. ;Contemporary magisterial teaching concerning the common good has introduced political theories that are not easily reconciled with the more traditional understanding advocated by Leo XIII. The newer statements leave ambiguities concerning some of the most fundamental questions. A return to Leo XIII is the first step towards a rethinking of the common good and a resolution of the current difficulties