An Ad Hominem Argument for the PSR

Not every ad hominem is a logical fallacy, nor is it necessarily a personal attack. In this instance, what the defender of the PSR proposes is that the skeptic's own presuppositions entail adherence to the PSR. Have you ever been involved in a discussion like this?:

Proponent: God exists because X, Y, and Z.
Opponent: Why should I believe Z?
Proponent: Because Z is based on the PSR.
Opponent: Why should I believe in the PSR?

Notice how bizarre that last question sounds if you step back for a moment to think about it. If it's not the case that every existing thing has an explanation of its existence (PSR), then why should the proponent of the PSR be required to give a reason in defense of the PSR? If there are so many exceptions to the PSR, then it seems arbitrary for the opponent to demand an explanation in this case but not in others.

It seems to me that the PSR is a first principle of rational inquiry, much like the assumption that an external world exists. Without such principles, all rational inquiry ceases. Moreover, if we assume that the PSR is false, that gives rise to all kinds of paradoxes and absurdities. The proponent of the PSR should also not overlook the strength of arguing from intuition. How many of us, Richard Taylor points out, upon walking by a glowing translucent ball in the middle of the forest, would conclude that the ball had no explanation whatsoever? My guess is that even the diehard skeptic would not hesitate to conclude that it has an explanation, whatever that explanation might be.

Observational Unity and Diversity

As I was at the gym today, I was drying my hands and noticed several rusted dots on the hand dryer. Obviously this device had been installed some time ago, at least long enough for rust to develop. As I looked at them casually, it occurred to me that they were distinct yet, in some sense, the same. If one dot had been green, for example, I may have assumed that some paint had somehow made it on the hand dryer. The fact that each dot, while distinct, was of the same rusted color, caused me conclude that each of these dots had arisen from a common source.

As we gaze in awe upon the universe's constants and order, we find a much more overwhelming sense of unity among diverse objects. Why is it that in one part of the universe gravity is present in much the same way as in another part? How about any of the laws of nature, or any existing thing for that matter? There is something so unbelievable about nature being uniform across the vastness of space, and yet it's this unbelievable conclusion that makes the most sense by a long shot.

God, our source of life, our hope, and our being, is at the beginning of it all, having created and now sustaining all that we see and all that is beyond our vision. If I, a lowly sinner, can see this on a men's locker room hand dryer, how much more ought we be able to see it in all of God's majestic creation?

Circumstantial Evidence and the Perpetual Virginity of Mary

In Luke 1:26-33, the angel Gabriel informs Mary that she will give birth to a child. Her response in verse 34 is quite interesting:

"'How will this be,' Mary asked the angel, 'since I am a virgin?'"

Notice that Mary's self-description of her virginity is in the present tense. She doesn't state that she will forever remain a virgin. On the other hand, Gabriel's declaration is in the future tense. Why, then, does Mary not just assume that in the future she will conceive in the natural way? Catholics, Orthodox, and some Protestants (but most Protestants today do not hold to this) believe that Luke 1:34 is indicative not only of Mary's present state, but also of her vocation.

The awkwardness of Luke 1:34 for the contradictory view is manifest in the gratuitousness of Mary's question. Where e = evidence (in particular, the passage we are discussing), h = the hypothesis that Mary remained a virgin throughout her entire life, and k = any background knowledge, P(h/e&k) > P(h/k). In other words, Luke 1:34, while not necessarily demonstrative evidence of Mary's perpetual virginity, does make this hypothesis more likely true than it would be without Luke 1:34.

Some-All Analogies and the Ontological Argument

The easiest way to express the ontological argument is like this (where "God" = a maximally great being, or a being that is omnipotent, omniscient, and morally perfect in every possible world):

1. God is either necessary or impossible. (Definition)

2. God is not impossible. (Premise)

3. Therefore, God is necessary. (From 1 and 2)

Transpositionally, (2) implies that God is possible. Given God's possible existence and S5, it follows that God exists. I argued earlier that one may demonstrate (2) by way of reductio ad absurdum. However, after giving it some further thought, I also think there is promise in arguing by way of analogy.

Take the proposition p1, "some of the existing apples are on earth." Now, according to Boolean logic, the quantifier, "some," does not necessarily imply that there are some existing apples that are not on earth. Nevertheless, given the possibility that p1, it is also reasonable to infer the possibility of p2, "all of the existing apples are X." In other words, the possibility of some implies the possibility, even if not the actuality, of all.

Applied to the ontological argument, we know that there are agents (such as ourselves) who possess some power, some knowledge, and some moral goodness in some possible worlds. If the some-all analogy is correct and taken to its logical conclusion, it follows that God possibly exists. This is all that is needed to show that (2) is true. Of course, (2) in conjunction with (1) implies that God is necessary, or has existence in all possible worlds.

Given that God exists in all possible worlds, and given that the actual world is a member of the set of possible worlds, it follows that God exists in the actual world. Therefore, God exists.

Of course, if one is not persuaded by the some-all analogy, then he/she will not necessarily accept the conclusion that God exists. For the rest of us, though, the knowledge of our limited perfections only confirm our conviction that God exists. As C.S. Lewis quips (and I paraphrase), we only know that a line is crooked if we have some idea of what a straight line looks like.

The TCA and Omnipotence

1. Every temporally contingent thing has a sustaining cause. (Premise)

2. If there is no First Cause, then there is an infinite regress of temporally contingent sustaining causes. (Premise)

3. There cannot be an infinite regress of sustaining causes. (Premise)

4. Therefore, a First Cause exists. (From 1 - 4)

5. Every existing thing is either omnipotent or non-omnipotent. (Definition)

6. Whatever is non-omnipotent can be generated. (Premise)

7. A First Cause cannot be generated. (Premise)

8. Therefore, the First Cause is omnipotent.

An omnipotent First Cause, as the Angelic Doctor muses, "everyone understands to be God."

Notice that the second half of the argument is almost identical to the Modal Third Way (MTW) that I defend on this blog. The first half of this version of the TCA, on the other hand, is more traditional.

As believers we often get the question: why does the First Cause have to be God?

This is a good and fair question, but it is also one that can be answered quickly with success. (5) - (8) show that the First Cause must have omnipotence, an exclusively God-like characteristic.