Tolkien’s metaphysics of evil, part 20
For St. Thomas, then, God is not in any way the cause of evil, yet he does permit and even “preserve” (Thomas’s word) or “guarantee” (Tolkien’s word) the actions of evil wills, much as the source of light preserves or guarantees the broken light emitted through a cracked prism or piece of glass, yet without becoming on that account morally or metaphysically responsible for or causative of the light’s brokenness. But the question still remains as to why God should choose to preserve or guarantee such broken wills and actions. One important answer for both Thomas and Tolkien is that the Creator desires that there should be such a thing as free will, even if what those free wills choose should turn out to be evil.
This, however, is only a partial explanation, for even the free choices of creatures fall under the providence of God as things in some sense willed, or better, “permitted” or “tolerated” by him, so that for Aquinas, at least, God could have willed that there be no evil in the world while still leaving the human will to be free (about which more anon). For both Thomas and Tolkien, a further explanation for God’s permission of evil concerns our next proposition in Tolkien’s metaphysics of evil, which is that evil makes possible the realization of even greater good. Thomas makes this point in response to the objection that evil cannot reside in those things made by God because, just as “white unmixed with black is the most white,” as Aristotle says, so “the good unmixed with evil is the greater good. But God makes always what is best, much more than nature does” (ST 1.48.2 obj. 3). While Thomas agrees that God, like nature, makes “what is best in the whole,” that is, in the “universe of creatures,” as with nature this does not necessarily mean that God makes “what is best in every single part” of the whole. According to Thomas, rather, the universe of creatures is in fact “better and more perfect if some things in it can fail and do sometimes fail, God not preventing this” (ST 1.48.2 ad 3). The greater good of the universe, or at least of this particular universe as it has been divinely ordered, requires not only the possibility of evil, but even its actuality, suggesting that, for the sake of the greater perfection of the world as a whole, the emergence of evil in the world was in some sense inevitable. As Thomas concludes his response, quoting Augustine’s Enchiridion,
“God is so powerful that He can even make good out of evil.” Hence many good things would be taken away if God permitted no evil to exist; for fire would not be generated if air was not corrupted, nor would the life of a lion be preserved unless the ass were killed. Neither would avenging justice nor the patience of a sufferer be praised if there were no injustice. (ST 1.48.2 ad 3)
 “[A]lbius est quod est nigro impermixtius… Ergo et melius est quod est malo impermixtius. Sed Deus facit semper quod melius est, multo magis quam natura.”
 “Ipsum autem totum quod est universitas creaturarum, melius et perfectius est, si in eo sint quaedam quae a bono deficere possunt, quae interdum deficient, Deo hoc non impediente.”
 “Deus est adeo potens, quod etiam potest bene facere de malis. Unde multa bona tolerentur, si Deus nullum malum permitteret esse. Non enim generaretur ignis, nisi corrumperetur aer; neque conservaretur vita leonis, nisi occideretur asinus; neque etiam lauderetur iustitia vindicans, et patientia sufferens, si non esset iniquitas.”