Yep, in case you didn’t know, there is now a Rational Catholicism YouTube Channel where posts here are made into videos!
Socrates, the father of philosophy, mentor of Plato—whom himself went on to become the mentor of Aristotle, who greatly influenced St Thomas Aquinas—never authored any works; however, many of his ideas and discussions were recorded by Plato in his “Socratic dialogues.” One of these recordings, entitled “Euthyphro,” recounts a discussion between Socrates and, the titular character, Euthyphro on what it means for something to be pious or good. Socrates seeks to learn the definition of that which is pious through a series of questions posed toward Euthyphro. Initially, it is concluded that that which is pious is that which is pleasing to the gods, but Socrates is quick to point out that as the gods quarrel, they, therefore, differ in what pleases them and in what they consider to be pious or holy. The discussion continues, yet they return to defining that which is pious as that which is pleasing to the gods. Needless to say, Socrates was not satisfied with this final conclusion.
Scholasticism—the philosophical school largely founded upon the works of St Thomas Aquinas, key school of theology within the western Church—quickly makes note of, and corrects, the error which leads to this unsatisfying non answer. In a similar fashion to the moral argument in making the case for the existence of God, this “pious argument,” if one wishes to call it that, argues against polytheism. The pious argument, in the searching for error in Socrates and Euthyphro’s attempt to answer the question, finds it unable to be answered within a polytheistic context—for unless all the gods are identical, and, therefore, one and the same god, there will be contradiction amongst them, as their natures will differ, resulting in them being pleased by different things. Therefore, should Socrates’ assumption that “piousness” exists and needs to be defined be true, in consideration that his proceeding logic is sound (which it is), there, therefore, must be only one God.