Volume 51, Issue 4, December 2011
Re-tracing the Five Famous Ways of Summa theologiae I.2.3
Aquinas’s Five Ways are not to be understood as demonstrative proofs, successful or not, for the existence of God. Rather, they provide a necessary step towards supplying licensable surrogates for the essential predications that cannot logically be drawn from the incomprehensible nature of God, yet would seem needed for the Summa’s declared genre of argued theology. (Predication secundum analogiam provides surrogates for non-relational accidental predications, likewise unavailable.) What Aquinas is proving in arguing deum esse in ST I.2.3 is not God’s actual existence (see ST I.3.4 ad 2) but an alternative interpretation of “God’s being something” where “God is something” is a placeholder for, say, “God is prime mover” or, more explicitly, for such (necessary) identities as “The prime mover is the necessitated necessitator,” an identity whose necessity depends at more than one place on the assumption of God’s existence from faith, not on demonstrative proof of God’s existence.