Van Til’s argument for Trinitarian Theism

We recently began looking at some presuppositional arguments from Van Til, as examined by James Anderson. One of Van Til’s more interesting arguments is one for the existence of a God that is not unitarian. Theoretically the same argument could be made for a God that exists in multiple persons of any number, not just 3. But for now, we will treat Christianity as the only worldview that has the requisite ontological commitments.

The argument is basically this: at the base level, reality is either fundamentally unity, diversity, or both. Reality being fundamentally unity or fundamentally diversity would undermine our knowledge of reality. Therefore if we are to know anything about reality, we must hold that reality is fundamentally both. Only Christianity presents a worldview under which this is true, so Christianity is true.

Here is Van Til:

As Christians, we hold that in this universe we deal with a derivative one and many, which can be brought into fruitful relation with one another because, back of both, we have in God the original One and Many. If we are to have coherence in our experience, there must be a correspondence of our experience to the eternally coherent experience of God. Human knowledge ultimately rests upon the internal coherence within the Godhead; our knowledge rests upon the ontological Trinity as its presupposition. (An Introduction to Systematic Theology, 23)

This is relatively easy to phrase in a more formal premise-conclusion form, so I won’t bother here. I am sure you can all reconstruct it.

What we must do now is justify the claim that under fundamental unity or under fundamental diversity, reality is not knowable.

 

Knowledge is impossible under diversity
Suppose that diversity is fundamental, and that every thing is distinct from every other thing. Knowledge therefore can only be had of individual things, and not categories. We can’t know things like “cats don’t like water” without all (or just most) cats having that property. But if there are no shared properties between objects, knowledge seems to be very difficult. We certainly want to affirm we have this kind of knowledge of classes and categories and groups, so we must deny that reality is fundamentally diverse.
Knowledge is impossible under unity
Under fundamental unity, where everything is at the base level the same kind of thing, knowledge seems impossible because there is nothing to differentiate one thing from another. We can only know that an object has a property A if there are some objects that do not have the property A. And perhaps more interestingly, if one knows something about an object, that it has a property A, it must be that we know it has a property A instead of property B. But under unity, there are no A and B, they are unified and identical. So between objects and within one object, knowledge depends on distinctions.
Isn’t it possible that fundamentally there are some things that are distinct and some that are similar?
Maybe. Suppose that this were the case, that fundamentally there are things of category A that are all the same and things of category B that are all the same (two kinds of monads) and they are entirely distinct from each other. We have distinction: Bs are not As. And we have unity. All As are As. This seems like it solves the problem of the unity/distinction tradeoff in the same way the Trinity does.
A possible monadology
Suppose that reality is fundamentally composed of monads, think of them like really small atoms for now. We cannot know one monad from another, other than by incidental properties like location or momentum (inasmuch as small objects have these). But these monads compose larger objects like chairs and cats. We can have knowledge about chairs and cats, they are real objects which share properties. They are unified and distinct in the right way. But they are composed of entirely unified monads. Where is the problem here? How would Van Til respond? I am not sure.
Conclusion
We are again seemingly left not totally convinced by Van Til. Maybe he is right that knowledge is impossible under fundamental unity and under fundamental diversity. But we don’t just know fundamentals, we know composites, and even if fundamentals are indistinguishable the composites aren’t.
More
Vern Poythress has done some interesting work expanding and explaining Van Til here, which I think is more promising than the work Van Til has done himself. But I am still not convinced that it is sufficient to demonstrate the existence of God.