1.There are, among things that can exist, degrees of value (goodness, nobility).
2.The assignment of degrees of value consists in comparing things as more or less similar to a possible thing of maximum value.
3.Therefore, there is a possible being of maximum value. (From 1, 2)
4.A being has maximum value if and only if it has maximum existence. (Convertibility of goodness and being)
5.Therefore, there is a possible being M of maximum existence. (Conclusion of the first part)
6.There is a necessary being (or plurality of necessary beings) N that is, in every possible world, possibly the cause of all existing things in that world. (From the Second and Third Ways)
7.Necessarily, if x is possibly the cause of the existence of y, then x has existence to the same or greater degree than y does. (Aristotle’s Alpha the Lesser principle)
8.Therefore, in every possible world w, N has the greatest degree of existence of anything that exists in w. (From 6, 7)
9.A being of maximum existence exists in some world w. (From 5)
10.Therefore, N has maximum existence in w. (From 8, 9)
11.A necessary being has the same degree of existence in every world.
12.Therefore, N has maximum existence in every world. (From 10, 11)
13.Therefore, N has maximum value in every world. (From 4, 12)
 
There is a potential problem with this reconstruction: step 5 (conclusion of the first half) isn’t strictly necessary. If N didn’t have existence to the maximum possible degree, then there would be a world w containing something with existence to a higher degree. But, then, N could not be the cause of that thing.

Perhaps we could take 1-5 as merely establishing the possible existence of a being of maximum value, which provides some independent support to the conclusion 13. But it would be nice to find some way to make 1-5 directly relevant to 6-13.

The following is not an exposition or explanation of any argument found in the texts of Aristotle or Thomas Aquinas, but it is inspired by their work, and located within the tradition.

​Let's begin by assuming that all change must have a cause. Another word for ‘change’ in this context is ‘passion’. Let’s assume, then, that every passion has a corresponding action. On this picture, the action of the agent is the cause; the passion of the patient is the effect. Causation always involves two or more substances. Here we will also introduce a principle of proportionate causality. It is obvious, for example, that actual change or passion can only result from actual action, involving an actually existing agent and an actually possessed active power. A merely potential event cannot be the actual cause of any actual change. A merely potential agent cannot act.
 
If we were to abandon this principle of ontologically proportionate causality, we would have no explanation for the asymmetry and irreflexivity of causation. That is, we couldn’t explain why a given passion couldn’t be its own cause, promoting itself from mere potentiality to actuality. This would be tantamount to rejecting the causal principle altogether.
 
Every passion must be located in time, since time is the measure of change. What is the temporal relation (if any) between an action and its corresponding passion? There are four logical possibilities: (i) the action is earlier than the passion, (ii) the action and passion are simultaneous, (iii) the action is later than the passion, or (iv) the action is unlocated in time. I will argue that only cases (ii) and (iv) are metaphysically possible.
 
Let’s say that an entity is temporal when it has a state that is located in time. In cases (i) through (iii), the agent has a state (namely, the action) that is located in time, so the agent must be temporal. Only in case (iv) can we have an atemporal or timeless agent.
 
If an agent is temporal, then all its states are actual or potential only relative to the various moments of time (see Koons 2020, Koons forthcoming). Therefore, we cannot say that the agent’s action is actual simpliciter but only that it is actual or potential at this or that time. We must also adapt our principle of causality to incorporate this relativity: for each passion, its corresponding action must be actual at the time at which the passion occurs. Actions occurring in the past or future are, at the time of the passion, merely potential. Hence, we can rule out cases (i) and (iii).
 
Every change must have a cause. If a temporal agent A acts at time t to produce a passion in some patient, then agent A must have undergone some change that eventuated in this particular action at time t. The agent has changed from not being the agent of a particular change to being the actual agent of that change. Hence, the change in the state of the agent requires a cause.
 
If all agents were temporal, this would lead to at least one infinite causal regress at each moment of time. We could then consider the whole plurality of things undergoing change at that time and ask, What causes them to change? Since these changes are all simultaneous, nothing prevents us from aggregating them together into a single, massive event. Given the principle of causation, this simultaneous plurality of events must have a cause that is both separate from itself and actual (at t). Since the plurality includes all changes occurring at this time t, the only possible cause of the plurality of changes would be the action of an atemporal agent. An atemporal action can act at any or all times without undergoing any change itself, and so without requiring a cause.
 

Good metaphysical arguments don’t operate in a vacuum. They occur within a theoretical framework provided by a successful, time-tested research program. The oldest and most successful research program in metaphysics is that of the so-called perennial philosophy, beginning with Plato and Aristotle, extended by the Neo-Platonists, and developed in Western scholastic philosophy. At the core of this program is the distinction between two modes of being, potential and actual, along with a commitment to a strong principle of proportionate causation, that is, the principle that the greater the effect, the greater the cause must be. Many contemporary philosophers have defended this program (myself included).
 
Another important assumption of the perennial philosophy concerns the dependent nature of time. Time is not merely a static dimension within which events and states can be located. Such a Block Universe picture of time would leave us with many inexplicable data, including the irreversible direction of time and causation, the fixity of the past and the openness of the future, the basis of the Second Law of Thermodynamics and other irreversible laws, and our universal experience of the passage of time. Aristotle provides a much more satisfying account of time in Book III of his Physics: time is simply the measure of change. Change is the more fundamental phenomenon, and the distinctive characteristics of time are derivable from the nature of change.
 
This hypothesis requires that change itself not be given a real definition in terms of time. That is, we must reject Bertrand Russell’s At-At theory of change (Russell 1922, Lecture VI), according to which a thing x undergoes change just in case it has one feature at some time t1 and a contrary feature at some later time t2. Instead, we must define change as Aristotle does. A thing x is undergoing change just in case there is some feature F of such a kind that x has a potentiality for F-ness that is in some degree of partial actualization. This definition does not make any reference to moments of time or their temporal relations of earlier and later. However, it does entail that if some entity x is undergoing change with respect to F-ness, there must be earlier and later times of such a kind that x is progressively closer to F at the successively later moments of time. Partial actualization requires at least two distinct modes of being (i.e., instants of time), one in which x is (still) only potentially F, and another in which it is actually F. In fact, there must be an infinite number of such instances, each with a different degree of actuality of x’s F-ness, with the full actualization of x’s potential for F-ness occurring in exactly one of these. The direction of time is determined by the prior direction of change: if x’s potentiality for F-ness is partially actualized, and this partial actualization corresponds to a set of moments, then the later moments in that set must be ones in which x is closer to being F.
 
Now let’s add to this picture the assumption that all change must have a cause. Another word for ‘change’ in this context is ‘passion’. Let’s assume, then, that every passion has a corresponding action. On this picture, the action of the agent is the cause; the passion of the patient is the effect. Causation always involves two or more substances. Here we will also introduce a principle of proportionate causality. It is obvious, for example, that actual change or passion can only result from actual action, involving an actually existing agent and an actually possessed active power. A merely potential event cannot be the actual cause of any actual change. A merely potential agent cannot act.
 
If we were to abandon this principle of ontologically proportionate causality, we would have no explanation for the asymmetry and irreflexivity of causation. That is, we couldn’t explain why a given passion couldn’t be its own cause, promoting itself from mere potentiality to actuality. This would be tantamount to rejecting the causal principle altogether.

It is important to recognize that accepting this Aristotelian framework does not depend on deciding the A Theory/B Theory issue. In particular, it does not depend in any way on so radical a thesis as Presentism—the view that everything that is actual is actual at the present time. It is compatible with Aristotelianism that there be infinitely many different modes of actuality, one for each moment of time, past, present and future. All that is required  is the assumption that to effect a change that is actual in mode t, the agent must have a power that is actual in that same mode, i.e., at that same time.
 
This viewpoint would not be consistent with a non-Aristotelian version of the B Theory—one in which every event at every moment of time is actual in exactly the same way. On such a Block Universe model, there is no room for defining change as the actualization of a specific potential. Such a model, as J. M. E. McTaggart long ago noted, fails to take seriously the reality of change.
 

Does the God of classical theism exist? The principal reason for thinking that God fits the profile defined by classical theism is this: we have good metaphysical grounds for believing both that some entity that fits this profile exist, and we have good theological grounds for believing that, if such an entity exists, it must be identical to God, that is, to the God of the Bible, the God of Abraham, Isaac, and Jacob. 
 
So, what is the profile of the God of classical theism? There are four crucial characteristics:
 
1.God is absolutely the first cause of all causable things.
2.God is atemporal.
3.God lacks any intrinsic, passive potentiality.
4.God has no distinct nature and no distinct act of existence: He is identical to His own act of existence, which is also His nature or essence.
 
It is noteworthy that this list does not contain any of the traditional omnis: omniscience, omnipotence, or omnibenevolence. I haven’t included personality on the list, nor such properties as having knowledge or will. I haven’t included God’s infinity or perfection or uniqueness. This is not because classical theism is silent on any of these points, but because, in the classical-theist tradition, all these divine characteristics follow from the four that I have listed. They are, from an epistemological point of view (that is, in the order of human understanding), secondary characteristics of the God of classical theism. These secondary characteristics are not points of controversy between classical and non-classical theists; in contrast, all of the primary characteristics on the list are quite controversial.
 
There are, therefore, two tasks which the classical theologian must complete: first, to argue successfully that some entity satisfies the four primary characteristics, and, second, to demonstrate that any being with the primary characteristics must also have the familiar secondary characteristics.