Aristotle and Aquinas
Main idea: Aristotle never set aside the principle of bivalence but instead presumed a distinction between “definitely true” and “indefinitely true” propositions (88). A human being can have opposing potencies, and even when one is actualized, the contrary potency doesn’t disappear but remains as a potency.
The Medieval Reception
It isn’t simply “either we are free or God knows everything.” Rather, as Augustine pointed out, there is an “order of causes in which the highest efficiency is attributed to the will of God” (Civ. Dei 5.9).
Let’s take the statement, what will be tomorrow is necessary. The medievals understood this statement to be mean: “Whatever is, when it is, cannot be in the same moment other than what it is” (Muller 107). To anticipate later discussions, while the future may not be “up for grabs” from God’s point of view, it is nevertheless contingent.
There is also a distinction between necessity and certainty. Necessity is lodged in the thing known and certainty in the knower.
Aquinas held that not all effects have necessary causes. Aquinas maintained free choice by saying rational beings have the potency to more than one effect. We have a simultaneity of potencies (SCG III.72).
Aquinas and Divine Power.
Muller then discusses the standard distinction of absolute vs. ordained power. This undergirds how God is said to relate to the world, and the world order itself is contingent result of God’s free willing (Muller 121).
Since this created order is contingent, “God has created contingent agents that act or cause effects contingently” (123). As a result, we have the potency to do otherwise. We should also point out the language of “determined” in the medievals. They weren’t thinking about the determinism vs. libertarianism debate. Determined simply meant the “terminus whether a quo or ad quem of a causal sequence has been identified” (130).
Therefore, per a future contingent, it is “undetermined” not in the sense that God is not aware of it, but that it doesn’t have a determinate cause. God knows future contingents as “hypothetically necessary, as the effects of contingent causes” (131).