A central thesis of Thomas’s natural theology is the claim that God is a being of pure actuality—meaning that God is utterly lacking in passive potentiality. This follows quickly from the fact that God is absolutely the first cause, in the sense of being the cause even of other necessities. God is the only being that is necessary in Himself. In order to act as first cause, God must be in His very essence fully equipped with a complete complement of intrinsic properties. If He were not, then there would be a component of contingency or at most conditional necessity in His intrinsic state as the first cause, but any such component would require a still more primary cause, contradicting God’s status as absolutely first.
God lacks only passive potentialities: He possesses active potentialities (i.e., active powers) to the greatest possible degree. God can cause anything that is metaphysically causable—His active power is without limit. If it were limited, then this limit would require some cause, again contradicting God’s status as first cause. God is, moreover, maximally free. He was free, in particular, to create nothing at all, or to create any cosmos that would be a fitting expression of His nature. There are many such possible cosmoses. Ours is just one. Hence, our cosmos is thoroughly contingent. How is the contingent exercise of active power on God’s part consistent with His lack of passive potentiality? In Aristotelian metaphysics, there is no conflict, since the exercise of active power is an action, and an action takes place in the patient, not in the agent. God does not have to modify Himself in order to exercise His active power. He does not have to deliberate or plan, and His intentional action requires no internal representation in His mind. The truthmaker for God’s intentionally creating creature x is simply the existence of x itself. No difference internal to God is required to differentiate worlds in which God creates x from worlds in which He does not. But, a critic may respond, isn’t God identical to His own action, given Thomas’s strong doctrine of divine simplicity? If so, the objection goes, since God exists necessarily, His action must exist necessarily, in which case everything that God creates must also exist necessarily. It is true that Thomas embraces the thesis that God is identical to His own action. In Summa Contra Gentiles, I, chapter 45 and in Summa Theologiae I, Q14, article 4, Thomas argues that God’s act of understanding is identical to His essence. Since He is identical to His own essence, God is identical to His act of understanding. In Part II of the Summa Contra Gentiles, Thomas claims both that God’s power is identical to His own substance, and that His action is identical to His power. Ordinarily, the act of a power is distinct from that power. So, if I whistle a tune, my particular act of whistling is obviously distinct from my power of whistling. However, in God’s case, His act of understanding is identical to His power of understanding, and both are identical to God Himself. The act of a power is the perfection of the power. A power that isn’t exercised is imperfect. So, if God’s act were distinct from His power of understanding, then that act would perfect His power. Furthermore, the perfecting of this power would be the perfecting of God’s essence. Hence, God’s perfection would depend on something other than God, which would contradict the fact that God is infinitely perfect. God’s act must be identical to God, so that it is God who perfects Himself. An act stands to a power as actuality to potentiality. So, if God were not identical to His act, then His power of understanding would have a potentiality that is actualized by His act. But God has no passive potentiality. He doesn’t stand as potential to anything else. So, He must be identical to His own act. The Modal Collapse Argument Many critics of Thomas argue that he is committed to God’s willing necessarily everything that He wills, because of Thomas’s strong doctrine of divine simplicity. The argument typically goes something like this:
The argument is guilty of a fallacy of equivocation. Understood in one way, the term “God’s act of willing to create this world” picks out something that exists necessarily, namely, God Himself. Understood in a second way, the term picks out something that exists only if this world exists. On either meaning, conclusion 5 does not follow from sub-conclusion 4. On the second meaning, the phrase “God’s act of willing to create this universe” is actually a kind of quantifier: “There is something that is uniquely an act of willing by God to create this universe and…” To make clear why 5 does not follow from 4 using the first meaning, the inference to 5 on that reading requires an additional assumption: 4b. God’s act of willing to create this universe is essentially God’s act of willing to create this universe. On the first reading, assumption 4b is false. God’s actual act of willing (which is in fact an act of willing that He create this world) could have been an act of willing that He create a different world, or no world at all. Consider, for example, a parallel proposition: BD. Ben’s father is essentially Ben’s father. Not true—although I am in fact Ben’s father, there are possible worlds in which I have no children at all. Critics of Thomas will complain that the cases are not parallel. Assumption 4b just must be true, because every act of willing has its own object essentially. My choosing a chocolate cookie for a snack could not have been my choosing an oatmeal cookie. Different objects necessarily imply different acts of will. However, this is wrong, for two reasons. First, because God is different from creatures. God does not have to undergo any kind of process of deliberation in order to make a choice. Hence, He and His act of will are exactly the same in every possible world. They have different objects in different worlds, but this difference is merely a Cambridge difference in God—it doesn’t require any internal modification. The objects of God’s choosing are immediately present to God as chosen by Him—they don’t have to be re-presented within God as chosen. Second, even in the case of human actions, it is possible for the same act of human willing to have different objects in different worlds. I’m thinking of a case of spontaneous but voluntary action—acts taken without any prior deliberation, but which are nonetheless guided by the human will. Consider, for example a musician who is improvising as he plays, or a speaker who is speaking very rapidly. The notes or words that are chosen are chosen by will, and yet there need be no prior mental event guiding the action. The action has “voluntariness”, as Elizabeth Anscombe puts it, without being the product of some internal volitional event. In a different possible world in which the person chooses a different note or different word, there may be no internal difference despite the fact that a different choice was made. Consequently, there is no reason to deny that the very same act of will could exist in both worlds. Let’s return to the argument and consider using the second meaning. On that interpretation, steps 4 and 5 look like this: 4c. There is something that is uniquely an act of willing by God to create this universe, and that thing exists necessarily. 5c. There necessarily exists something that is uniquely an act of willing by God to create this universe. Again, 5c does not follow from 4c, unless we assume that anything that is in this world an act of willing by God to create a certain universe must be an act of God to create that same universe in every possible world in which it exists. Again, we have to assume that God’s act of willing is essentially an act of willing to create this universe specifically. And that Thomas will deny.
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All of Aquinas's Five Ways depend, in one way or another, on ruling out the possibility of infinite causal regresses. In the version of the First Way (the argument from motion) in the Summa Contra Gentiles (I.13), Aquinas follows Aristotle in offering two separate arguments against the causal regress. In the first three ways in the Summa Theologiae, he offers just one of the two Aristotelian arguments: an argument that depends on what I call the No-Intermediate-Real-Cause thesis. This is a thesis that states that if x is a cause of y, and y is a cause of z, then y is not really a cause in the strict sense but only secundum quid (only in a manner of speaking). An intermediate link in a causal chain is not in any sense the source of the reality of the ultimate effect--it is merely a conduit through which the first cause acts. Therefore, an infinite regress is impossible, because (as Aristotle and Aquinas note) every link in the regress would be only an intermediate cause. Hence, such a regress cannot contain any real causation.
This is a plausible argument, despite the fact that it is often dismissed as based on a fallacy of equivocation. The standard objection (going back at least to Cajetan, I believe) is that Aquinas equivocates on the phrase "removing the first cause." If we have a finite chain and we hypothetically remove the first cause from the series, it is obvious that none of the intermediate causes can act. Aquinas asserts that if we consider any infinite regress, we have a situation from which we have (in a sense) "removed the first cause". But, as critics point out, in this case there never was a first cause to be "removed", and so the cases are incomparable. However, Aquinas real point is simply to claim that intermediate causes are never causes in their own right but are always wholly parasitic on the first cause. Given that assumption, infinite causal regresses are indeed impossible. The other strategy for dealing with infinite regresses was invented by Avicenna, followed by Scotus, Leibniz, and many subsequent thinkers (including me in 1997). This is the Aggregation Strategy. The Aggregation Strategy concedes, for the sake of argument, that infinite regresses are possible. However, the Strategy insists, if a regress consists entirely of contingent (or finite) things, then we can aggregate the whole series into a single entity and insist on a cause for it. Start now with a single finite thing, and consider all of the finite causes of that thing (whether immediate or remote). Either this series terminates in an uncaused thing, or else it constitutes an infinite regress. In the latter case, we can demand a cause for the whole series. This cause must be infinite, since any finite cause of the series would be a cause of the original entity and so would already be included in the series itself. A member of the series cannot cause the whole series. An infinite thing cannot be caused. And so we reach an uncaused first cause. Aquinas was aware of this strategy, through his close reading of Avicenna. Why didn't he adopt it? I think he was worried that not all infinite series can be aggregated into a single entity. If an infinite series consists of entities of the same species (or a finite number of species), then it has the characteristic that Aquinas labels being accidentally infinite. An accidentally infinite series can be aggregated and must be caused as a whole. This is why Aquinas can concede that accidentally infinite series might exist without losing the force of his first cause argument. However, if an infinite series consists of entities of an infinite number of species, with the species climbing progressively higher and higher in the Great Chain of Being, the Aggregation Strategy could not be convincingly applied. Aquinas would call such a series essentially infinite, and he must (if the Second or Third Way is to work) deny the metaphysical possibility of such a series. This is why he appeals to Aristotle's argument and what I call the No-Intermediate-Real-Cause thesis, which should now be applied only to series that rise "vertically" through the ontological order of species. I've been working a lot lately on Aquinas's First Way, the argument from motion, which builds on Aristotle's arguments in Books 6, 7, and 8 of the Physics, and which Aquinas develops at length in the Summa Contra Gentiles, Book I, chapter 13. Aquinas calls it the "most manifest" way of proving God's existence, but it has not been popular with commentators or critics. Sir Anthony Kenny is thoroughly dismissive of it in his book on the Five Ways. He quotes Suarez, who wrote: "Taken by itself, this argument is shown in many ways impotent to prove there is anything immaterial in reality, let alone that there is a first and uncreated substance." (Disputationes metaphysicae XXIX, I, 7)
The basic argument is quite simple: 1. Some things are in motion (experience change). 2. Everything that is moved is moved by something else (no self-moving). 3. A chain of movers cannot regress to infinity. Therefore, there must be at least one unmoved mover. Almost everyone accepts premise 1, so all of the action concerns premises 2 and 3. In addition, the argument faces a serious "gap" problem: how does one get from an unmoved mover to a "first and uncreated substance" (as Suarez puts it)? By paying careful attention to the arguments, and by exercising a little imagination and creativity, we can rehabilitate the First Way into an argument that deserves consideration alongside the many other sound theistic proofs that have been crafted recently. Before getting into the details, we have to consider first what Aristotelians like Aquinas assume about the nature of change and time. There are essentially only two options here: either time is fundamental, and change is definable in terms of time (Russell's at-at theory of change), or change is fundamental and time is definable in terms of change (time is the "measure" of change). There are very strong considerations in favor of the second, Aristotelian option. At-at theorists have never been able to develop a successful explanation of the direction of time or of causation. See, for example, Huw Price's Time's Arrow and Archimedes' Point, or Alex Pruss's critique of David Lewis's counterfactual-conditional account of time's arrow. In addition, at-at theorists cannot explain how we are able to measure the true duration of processes, without making the ad hoc assumption that each kind of process has a fixed velocity (like the speed of light). Aristotle's option avoids both of these defects. Famously (or, infamously, depending on your point of view), Aristotle defines change in Book III of the Physics as the actuality of the potential qua potential. Aquinas does a good job of unpacking this somewhat cryptic statement in his commentary on the Physics (Lectures 2 and 3 of Book III). Potentiality is, for Aristotle, something real and irreducible. It is a feature of all natural things, a kind of "natural intentionality" as David Armstrong and George Molnar put it. When a thing has a certain potentiality, it is pointing in a specific direction to a particular, non-actual situation. Motion occurs when such a potentiality is partially but not completely actualized. Take a stone that is in the process of becoming hotter. Let's say that the stone is currently lukewarm. The stone has both the potential of being colder and the potential of being hotter, but only one of these two potentialities is now partially actualized, namely, the second of the two. That is what constitutes the stone's becoming hotter. Once the stone has reached its equilibrium state, it will have fully actualized that potential and will no longer be in motion (change). At that point in time, neither of the stone's potential will be partially actualized. Both will exist only in a state of perfect potentiality. All change is, therefore, inherently directional. It is always change toward some unrealized state or states. Time passes as change occurs, and time itself is therefore also directional, pointing from the terminus ab quo and toward the terminus ad quem of the process of change. Moreover, the measure of time consists in the completion of certain standard processes, like the movement of light across a fixed distance. Thus, there is no mystery about the arrow of time, nor about the fixity of the velocity of these standard processes. In addition, the Aristotelian option yields the impossibility of time travel, since this would involve making the end of a process into its beginning. Time passes because change happens, and not vice versa. Once we grasp this, we see that any law of inertia is completely irrelevant to the argument from motion. A law of inertia dictates that a body will continue to move in a straight line and at a constant speed as time passes. The inertial motion of the body thus depends on the movement of time and cannot be the explanation for the passage of time. The passage of time requires the continuous occurrence of change that is independent of time, in a way that no merely inertial motion can be. Thus, the First Way points us toward a crucial metaphysical question: what is the source or explanation of this time-independent change? |
AuthorRob Koons, a professor of philosophy, trained in the analytic tradition at Oxford and UCLA. Specializing in the further development of the Aristotle-Aquinas tradition in metaphysics and the philosophy of nature. Archives
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