This dissertation argues that neither inconsistency nor a theological treatment of natural law was involved when Aquinas wrote that the prescriptions to love God above all and to love neighbors as self are the first principles of natural law, self-evident to human reason through nature. The argument is extended through two volumes. ;Volume one: Foundations of natural law. This volume accomplishes four tasks. First, it uses Aquinas' generic definition of law and his specific definition of natural law to determine the (...) essential characteristics of a natural law principle's obligatory power, self-evidence, promulgation, and reliance upon natural inclinations. Second, it explicates how the Bonum precept, "Good is to be done and pursued, and evil avoided," functions within natural law; this explication shows that the status of first principle can be assigned to more than one precept. Third, it explains the relationship between natural law principles and derived precepts, particularly those of the Decalogue. Fourth, it shows that the essential characteristics of natural law principles preclude those principles from being dependent upon faith and Christian revelation. ;Volume two: Love and the natural law. This exegetical argument involves explicating the nature of loving God above all and loving neighbor as self in order to show that the prescriptions of these loves possess the essential characteristics of natural law principles. Accordingly, this volume uses the findings of Volume One to show that natural law prescribes a love of God above all and a love of neighbors as self which cannot be identified as prescriptions of charity, that these prescriptions are self-evident principles of natural law, and that they are natural law's first and primary principles. (shrink)

Aquinas does not argue that natural inclinations per se suffice for moral absolutes, but rather that they suffice to make their objects known as self-evidently good for persons. Acting for the contrary of a natural inclination thereby harms persons and is contrary to the Bonum Precept (Good is to be done and pursued; evil is to be avoided). Acting for a self-evident good, however, becomes morally obligatory only when indispensable.

Aquinas argues that love of others depends on whether the other is seen as a person like oneself or as a tool of gratification. The former grounds love-of-friendship (altruistic love), the latter love-of-concupiscence. Seeing the other as a person like oneself enables one to love the other as another self, thereby, basing altruism ultimately on self-love.