  In addition to such common sense considerations, the medievals also identify various philosophical and theological grounds for opposing anti-realism about relations. Here we shall mention just two. First, it is hard to see how such anti-realism is to be squared with the standard interpretation of the Aristotelian categories. “For nothing is placed in a category” as Aquinas says “unless it is something existing outside the soul” (De potentia, q. 7, a. 9). Again, this sort of anti-realism seems incompatible with the orthodox Christian view of the Trinity. Indeed, it is precisely for this reason that the existence of real relations in God is affirmed at the Council of Rheims in 1148, and that shortly thereafter it becomes customary to say that the denial of this entails a form of heresy known as Sabellianism (Cf., e.g., Aquinas, Summa Theologiae I, q. 28, a. 1 and De potentia q. 8, a.1).