Authored by: Mitchell LeBlanc.
Author’s Note: This post is part of a series which has culminated in a scholarly paper on the topic. As such, I kindly ask that any criticism of the subject matter therein is given with a cognizance of the most recent material on the subject.
Presuppositionalism is a branch of apologetics which, instead of offering the classical arguments in favor of God’s existence, attempts to show that any worldview which does not presuppose the Christian God is internally incoherent. This type of apologetic has been defended by the likes of Van Til, Greg Bahnsen and John Frame. Defenders of presuppositional apologetics with whom I am more familiar include the folks over at Choosing Hats.
Presuppositional apologetics have always seemed to be more of a set of debating tactics rather than a epistemic system. However it is pertinent to treat it as what it claims to be for the sake of discussion.
Spawning from presuppositional apologetics is an argument known as the TAG, or the Transcendental Argument for the Existence of God. Presuppositionalism produces nowhere else (to my understanding) a formal argument for its claim. As such, if one wants to thoroughly provide a critique of presuppositionalism, it seems necessary that they offer a critique of the TAG as well.
Succinctly, presuppositionalism argues that the Christian God is necessary for the intelligibility of various features of human understanding (logic, morality, meaning). It does so by making a transcendental argument. Transcendental arguments take the following form:
A: For X to be the case, Y would have to be the case, because Y is a precondition of X
B: X is the case
C: Therefore, Y is the case
Contextualized, this argument becomes:
A: For there to be intelligibility in the world, God must exist because God is a precondition of intelligibility
B: There is intelligibility in the world
C: Therefore, God exists
The support for A is often a series of claims that non-Christian worldviews cannot make sense of the various features of human understanding coupled with the notion that if it is impossible for non-Christian worldviews to justify intelligibility and intelligibility exists, it must thereby only be justified by a Christian worldview.
It is also important to note that presuppositionalists state that their reasoning operates using two axioms. To quote a presuppositionalist with whom I have debated:
As a Christian, I have two axiomatic, interrelated foundations for my epistemology, and for everything else I encounter through the grid of that epistemology. The Triune God of Scripture – who created the universe and all it contains; who established and even now maintains the laws which govern that creation. That is foundation one.
The self-revelation of that self-existent, self-conscious, self-sufficient, omniscient, omnipotent, all-wise, immutable, eternal, and sovereign God; The Scriptures of the Old and New Testament, are the self-communication of the extent, nature, and specifics of His eternal properties – which are the guarantor of the laws and assumptions which we, as creatures in the image of that God, require to operate rationally and coherently. That is foundation 2.
God as an axiom
For the purposes of this discussion, I will focus on the claim that logic is dependent on the Christian God. Presuppositionalists do not stop merely at logic, but assert that morality, science, etc all presuppose their Christian God. I’ve chosen to address only the logic portion of these claims because I see it as the most important issue, and if it can be shown that logic does not depend on the Christian God it seems that presuppositionalist apologetics are defeated.
First and foremost, one should note the peculiarity of the espoused axioms of presuppositionalism. They are in fact, not axioms. My colleague Dawson Bethrick outlines this comprehensively on his blog, but I wish to do so in a slightly different manner.
A statement must satisfy three conditions to be considered axiomatic:
It must be irreducible to prior concepts
It must be self-evident to introspective and extrospective acts of cognition
It must be undeniable without direct contradiction
The concept of “God” fails to meet each of these:
One can reduce the concept of God to an unembodied mind, thereby rendering the concept of God as non-foundational
The concept of God is not self-evident to all acts of cognition
The denial of God does not lead to direct contradiction, in stating that “God does not exist” one is making use of various axioms but not presuming the existence of God.
As such, we can reject the notion that God is an axiom.
Logic and God
As stated, the presuppositionalist will say that the very existence of logic (or logical absolutes) depends on the existence of the Christian God. Philosopher Michael Martin analyzes this claim in his Transcendental Argument for the Non-existence of God (TANG). This argument is often dismissed by presuppositionalists, but I have yet to hear a compelling case as to why such a dismissal occurs.
The portion of the TANG which deals with logic is as follows:
1. Logic presupposes that its principles are necessarily true.
2. According to the brand of Christianity assumed by TAG, God created everything, including logic; or at least everything, including logic, is dependent on God.
3. If something is created by or is dependent on God, it is not necessary — it is contingent on God.
4. If principles of logic are contingent on God, they are not logically necessary.
5. If principles of logic are contingent on God, God could arrange matters so that a proposition and its negation were true at the same time. But this is absurd. How could God arrange matters so that New Zealand is south of China and that New Zealand is not south of it?
6. Hence logic is not dependent on God, and, insofar as the Christian world view assumes that logic is so dependent, it is false.
The argument is formally valid, so we must discover whether or not it is sound. Premise (2) is usually called into question as being a misunderstanding. For many Christians God did not create the laws of logic, it is claimed that they exist as part of God’s nature.
In taking the statement that “Logic exists as an intrinsic part of God’s nature”, one can deduce that if God did not exist than there would be no logical absolutes. That is to say if God does not exist, the law of non-contradiction can be denied.
But is this the case? We can cite such an argument from Van Til himself in his “The Defense of the Faith” (pg 256-257):
(7) If the Christian God did not exist, then predication would operate against a background of bare possibility.
(8) If predication operates against a background of bare possibility, the predication of P to x ( x is P) may be reversed and ~ P might be predicated of x ( x is ~ P)
(9) But if the predication of P to x ( x is P) is reversed and ~ P is be predicated of x ( x is ~ P), then the Law of Non-contradiction must be denied.
(10) Therefore, If the Christian God did not exist, then the Law of Non-contradiction must be denied
For the readers who are not particularly philosophically inclined, the above argument is saying that the law of non-contradiction (which states that someone cannot be X and not X simultaneously) can be denied if God does not exist. Thereby attempting to show that if God does not exist we can say that the apple is orange and that the apple is not orange, because there is no law of non-contradiction.
Interestingly enough, (7) makes mention of a background of bare possibility which presumably refers to logical possibility. But in order to have logical possibility, one must have the law of non-contradiction. That is to say, logical possibility is determined by the law of non-contradiction. The premise hinges on being an incoherent notion.
(7) further states that if predication operates via logical possibility, then we may reverse the predications completely. The suggestion is to say that we can have an apple be orange at one time and not orange at another time. Granted, but this is no way necessitates that the apple can be orange and not orange simultaneously. Henceforth, (9) is false. Reversing the predicate does not change the Law of Non-Contradiction. As such, the argument is unsound and we can reject (10).
Perhaps the modern presuppositionalist would object to Van Til’s formulation, asserting that the mere denial of God’s existence is logically absurd outright. Such an assertion would state that it is incoherent to deny the existence of God because of his very nature (he necessarily exists).
Consider the following:
(11) It is not the case that it is not that P and not P (law of non-contradiction denied, meaning it would be possible for your apple to be both orange and not orange simultaneously)
(12) It is not the case that God exists
In attempting to affirm (11), one arrives at an obvious logical incoherence. How could an apple be both orange and not orange simultaneously? In this sense, it is logically incoherent to affirm (11). But is it as logically incoherent to affirm (12), as the presuppositionalist states?
There is no self evident incoherence in affirming (12) and thereby denying that God exists. The only way there would be such an incoherence is if we applied a premise which stated:
(13) It is logically necessary that God exists
With the establishment of (13) it becomes obviously incoherent to affirm (12) and deny the existence of God. But how can the presuppositionalist assert (13)?
To say that it is logically necessary that God exists is to affirm the conclusion of an Ontological Argument. It is essentially saying that God cannot fail to exist because of his nature. But the presuppositionalist has chosen to forego classical arguments for the existence of God and thereby cannot support this claim! Why should one accept that it is logically necessary that God exists without an Ontological Argument to defend such a conclusion?
In effect, the presuppositionalist has shot themselves in the foot by choosing to dismiss classical arguments for the existence of God. The presuppositionalist requires one, but is unable to use one (by virtue of their own apologetic).
It should also be further noted that (13) is often confused for another premise. There is a difference between God necessarily existing and God (if existing) necessarily having no beginning or end.
(14) It is logically necessary that if at any time God existed, then at every time He existed
While (14) is required in presumably every branch of Christianity, and with good philosophical warrant, (13) isn’t.
As such, we can reach a couple of conclusions:
Firstly, God cannot be asserted as an axiomatic concept. Secondly, if logic is created or dependent on God, than it is not necessary and insofar as logic presupposes that its principles are necessarily true, logic simply cannot be based on the Christian God. Furthermore, if one is to say that logic exists necessarily as a part of God’s nature it becomes a logical consequence that denying the existence of God would lead to the denial of the law of non-contradiction. Since it has been shown that such is not the case without assuming the conclusion of a successful ontological argument we can reject this notion altogether.
At this point it seems that presuppositionalist apologetics are dead in the water. By its very nature presuppositionalism has rejected the classical theistic arguments and such arguments have become the very thing needed to keep presuppositionalism afloat.