Communion and Stewardship:
But it is important to note that, according to the Catholic understanding of divine causality, true contingency in the created order is not incompatible with a purposeful divine providence. Divine causality and created causality radically differ in kind and not only in degree. Thus, even the outcome of a truly contingent natural process can nonetheless fall within God’s providential plan for creation. According to St. Thomas Aquinas: “The effect of divine providence is not only that things should happen somehow, but that they should happen either by necessity or by contingency. Therefore, whatsoever divine providence ordains to happen infallibly and of necessity happens infallibly and of necessity; and that happens from contingency, which the divine providence conceives to happen from contingency” ( Summa theologiae, I, 22,4 ad 1). In the Catholic perspective, neo-Darwinians who adduce random genetic variation and natural selection as evidence that the process of evolution is absolutely unguided are straying beyond what can be demonstrated by science. Divine causality can be active in a process that is both contingent and guided. Any evolutionary mechanism that is contingent can only be contingent because God made it so. An unguided evolutionary process – one that falls outside the bounds of divine providence – simply cannot exist because “the causality of God, Who is the first agent, extends to all being, not only as to constituent principles of species, but also as to the individualizing principles…It necessarily follows that all things, inasmuch as they participate in existence, must likewise be subject to divine providence” ( Summa theologiae I, 22, 2).