Augustinian Influence On Gordon Clark

I'm not a presuppositionalist myself, but the respective works of Gordon Clark and Cornelius Van Til (in addition to Bahnsen, Frame, et al) are all thought-provoking. One of the influences of St. Augustine on Clark is the claim that the use of logic presupposes God's existence by the very nature of logic itself. Augustine uses the example of 2+2=4, whereas Clark claims that the laws of logic correspond to the divine attributes.

Let's take the example of the transitive axiom: if A=B and B=C, then A=C. This axiom, expressed as a proposition, is objective and unfalsifiable. It holds at all times, which means it is eternal. It also holds in all places, implying its omnipresence. The truth of logic cannot be changed into its contradictory, or negation, so it follows that it is changeless. Finally, contradictory systems of logic cannot both be true; this means that logic is one. In sum, we know that logic possesses the attributes of eternality, omnipresence, immutability, and unity. This already sounds rather God-like. Left without further analysis, however, we're left with a merely impersonal God, something like a vague principle of intelligibility.

If we combine this proof with conceptualism, on the other hand, then we can show how it makes sense to postulate the existence of a necessary mind. This would be a sort of "closing-of-the-gap" between logic and God. After all, the Logos referred to in John 1:1 is logic itself (Clark even translates John 1:1 as: "In the beginning was the logic, and the logic was with God, and the logic was God"), but it is also personal. We're often in the habit of treating logic as if it were this impersonal abstract principle, but in conjunction with conceptualism, we can show how the use of logic can be part of a rationally compelling proof of God's existence. We can summarize the argument as a reductio ad absurdum:

Prove A: God exists.
Assume ~A: God does not exist.
~A --> B: If God does not exist, then logic is not objective.
~B: Logic is objective.
Hence, ~~A: by modus tollens.
Therefore, A: God exists.
Q.E.D.

Of course, the proponent of this argument will have to argue in favor of both realism and conceptualism.

Duns Scotus and the Cosmological Argument

It amazes me how modal intuitions were already quite sophisticated in the Middle Ages. I think we often give ourselves too much credit - or conversely, we don't give our predecessors enough credit - when it comes to philosophical and scientific advances. As early as the thirteenth century, Catholic philosopher, John Duns Scotus (so-named because he was a Scot) came up with this argument for a First Cause of essentially-ordered causes:

1. A First Cause is possible.
2. Whatever is possible is either contingent or necessary.
3. Whatever is contingent can be actualized.
4. A First Cause cannot be actualized.
5. Therefore, a First Cause exists necessarily.

The argument makes use of a weak version of the principle of sufficient reason (W-PSR). (1) should appear obvious to most of us. For, if a First Cause were not possible, then it would (by definition) be impossible. But, in order for something to be impossible, there must be a contradiction in the concept of it. The challenge is then for the opponent of the argument to demonstrate the impossibility of (1). I know of no argument that would even begin to suggest this.

(2) simply provides us with our available options. Since we have ruled out the First Cause's impossibility, the First Cause either exists in some but not all possible worlds (i.e. it is contingent), or it exists in all possible worlds (i.e. it is necessary).

(3), I think, is the crucial premise. The best way to support it is likely by connotation. We can simply provide examples of contingent things being actualized. For instance, it is possible that Planet-X should come into being at time-t. Yet, Planet-X (by hypothesis) does not exist in all possible worlds, even though it can be actualized in those worlds where it does not yet exist. Hence, we can think of Planet-X as a contingent entity.

Now, (4) ought to be granted upon reflection. If a First Cause were actualized, then it either actualizes itself, or else it is actualized by something causally prior to it. The First Cause obviously cannot be actualized by something causally prior to it; for then it would not be first in the series of efficiently-ordered causes. Nor can the First Cause actualize itself. In order for something to actualize itself, it would have to exist before causing its own existence, which is absurd.

(5) follows as a result of the truth of premises (1)-(4).

The Modal Ontological Argument

I've never really endorsed the ontological argument, in any of its forms. One version, however, that has interested many contemporary philosophers is Alvin Plantinga's modal ontological argument. More novel still is Robert Maydole's version of the argument, which appears in The Blackwell Companion to Natural Theology. I have to say that, while I'm not persuaded that these arguments are rationally compelling, there very well may be something to Plantinga's claim that the modal ontological argument at least provides rationally acceptable reason to believe in God. Plantinga himself puts the argument this way:

1. There exists a possible world in which maximal greatness is instantiated.
2. A being is maximally great if and only if it is maximally excellent in every possible world.
3. A being is maximally excellent if and only if it is omnipotent, omniscient, and perfectly good.
4. Hence, a maximally great being exists in every possible world.
5. Therefore, an omnipotent, omniscient, and perfectly good being exists.

Perhaps surprisingly, premises (2)-(4) are relatively uncontroversial. Essentially, the argument merely defines maximal greatness in terms of maximal excellence, which in turn is defined as exemplifying the properties of omnipotence, omniscience, and perfect goodness. It seems quite natural to say that there cannot logically be a greater being than this.

The proof also makes use of the so-called "S5 axiom," which states that if something is necessary in one possible world, then it exists in all possible worlds (necessity = instantiation in every possible world). This axiom is likewise uncontroversial.

The premise that is the most contested is (1). The first time I began researching this argument, I was caught off guard that anyone would question the bare possibility of God's existence. After all, wouldn't the opponent of the first premise have to demonstrate some contradiction with the idea of a maximally great being in order to soundly reject (1)? I believe this is the case, and while even a great many atheistic philosophers reject the notion that there is some inherent contradiction between the divine properties, that doesn't stop others from attempting to prove that there is such a contradiction.

This is why, in God, Freedom, and Evil, Plantinga first deals with J.L. Mackie's "logical problem of evil" before delving into the modal ontological argument. He systematically demonstrates that there is no contradiction between the reality of evil and the existence of a maximally great being. This gives us prima facie reason to accept the first premise of the modal ontological argument. It seems that in order to produce a defeater for (1), the atheist must be able to positively undermine the possibility of God's existence. This is quite a task.

On the other hand, Maydole has apparently tried to demonstrate that (1) is not only rationally acceptable, but that we can know its truth. I have yet to give his version of the argument more than a cursory look, so at the moment I'm unable to comment any further.