Presuppositional apologetics is a form of Christian apologetics, primarily in the Calvinist tradition, that asserts that the acceptance of either the proposition "God exists" or the Biblical inerrancy is necessary in order for the world to be intelligible. Presuppositional apologetics typically rejects Thomist apologetics, which accepts the rules of logic prior to arguing for the existence of God. There are two historically distinct branches of presuppositional apologetics: Van Tillian presuppositionalism and Clarkian presuppositionalism, attributed to their namesakes, Cornelius Van Til and Gordon Clark.
"[We] should present the biblical God, not merely as the conclusion to an argument, but as the one who makes argument possible (...)"
- "The battle is not over evidence but over philosophical starting points: presuppositions. As Christians, we should never put away our axiom—the Bible—when discussing truth with others. This would be like a soldier going into battle without any armor or weapons. "
- "By demonstrating that unbelievers can not argue, think, or live without presupposing God, presuppositionalists try to show unbelievers that their own worldview is inadequate to explain their experience of the world and to get unbelievers to see that Christianity alone can mkae [sic] sense of their experience. "
The Transcendental Argument for the existence of God (TAG) is often considered a claim of presuppositional apologetics, though it is also used (in a somewhat different form) in Thomist apologetics. The argument has also associated with the claim that "Atheists know there is a God".
Basic Forms and Principles
Van Tillian Presuppositionalism
Van Tillian presuppositionalists treats the Bible is the sole arbiter of whether a proposition is true or false; as a result, all knowledge claims must be given Biblical justification. They cannot be known independently of the Bible.
The laws of logic and causality are considered as true but not foundational. Rather, apologists assert that those propositions are true if and only if the truth of the Bible has been granted. In this argument, the basic laws of logic must be supported by Biblical justification.
- Skeptic: Is the logical law of modus ponens the case?
- VT Apologist: Of course modus ponens is the case. It is one of the most important rules of logic.
- Skeptic: But isn't modus ponens, given its standing as a rule of logic, foundational?
- VT Apologist: No. Only the Bible is foundational. Modus ponens can be used to check the coherence of other propositions with the truth of the Bible.
Apologists claim there are conclusive proofs of the existence of God based on logic. However, Van Tillian presuppositionalism draws a distinction between proof and persuasion. Van Til recognizes that many of these proofs are not pragmatically persuasive. Van Til asserts that this is because the skeptic rejects the epistemological framework (Platonic epistemology) necessary for the acceptance of those proofs. Van Til advocating Platonic epistemology as the only epistemology that is Biblically defensible.
Plato's epistemology differs from Van Til's in one very important respect: Plato does not accept the Bible as the foundation of his epistemology. For Plato, the Forms are foundational, and there is no text which can communicate the forms to individuals. For Van Til, the Forms are secondary to the belief in God and the truth of the Bible, and belief in the Forms is justified by the Bible.
Transcendental argument and variants
- Main Article: Transcendental argument
While presuppositional apologetics is as much a system of belief as anything else, it is sometimes presented as an argument to non-believers as: 
- All we experience is grounded in the laws of logic.
- The Christian worldview alone adequately explains and accounts for the laws of logic.
- Therefore, all we experience cannot be explained or accounted for outside of the Christian worldview.
Since the second premise is disputed, the more fundamental form of the argument is: 
- Logic (or reason or knowledge, depending on the variation used) requires justification.
- Atheists cannot provide a justification.
- Therefore, God is necessary in providing a justification.
Of course, there are multiple problems with this argument. Eric Hovind and Sye Ten Bruggencate have similar variants of this argument that they follow in a checklist/script fashion. Their fundamental aims are to question a non-believer's basis for their reason and their reliance on their senses, and then launch into the non sequitur that God or the Bible resolves the supposed difficulties. 
The transcendental argument of the argument runs:
- If there is no God, no knowledge is possible.
- Knowledge is possible.
- Therefore, God exists.
Van Til popularized a version of TAG, based on the role of the reciprocal relationships of the ontological trinity. There is some confusion about the exact structure of the argument, as it varied throughout Van Til's own writing. However, the traditional formulation is that the reciprocal relationships of the Trinity, being higher order relationships that exist outside of a relationship to the physical world, are the fundamental basis for logical relationships, and so reason is contingent on the existence of the Trinity. These arguments are rather strange because it claims the Biblical account of God to be foundational for the laws of logic, instead of allowing the laws of logic to be primitive. This version of the argument is problematic, because the relationship between entities is a synthetic statement while the laws of logic are analytic statements (the distinction was proposed by Kant).
Clark treated the truth of the Bible as though it were one of the axioms of a logical system. Other logical principle may be foundational, as long as they are compatible with the Bible. Clark asserts that the worldview that results from the acceptance of the Biblical axiom can be tested for consistency and comprehensiveness. Clark focused on demonstrating that there are no discrepancies or contradictions which can be produced by accepting the Bible as true, and embraces the possibility of using formal logic as a method for testing the propositions in order to ensure this. Because the Bible is foundational to a logical system, if any other logical rule produces any contradiction, then that logical rule must be rejected.
The idea that the Bible should be examined for possible contradictions draws some criticism from the Van Tillian branch, because they feel that the Bible should not be weighed against logical axioms. If an axiom is found to, hypothetically, demonstrate a contradiction within the Bible, then the problem is the axiom. Because Clark accepts that the laws of logic have bearing on falsifying the Bible, Van Tillian's often argue that this is not a genuine sort of presuppositionalism, and that it puts the laws of logic on the same foundational basis as the Bible.
Begging the question
- "But are we not still forced to say, 'God exists (presupposition), therefore God exists (conclusion),' and isn't that argument clearly circular? Yes, in a way. "
- "If Scripture is the ultimate justification for all human knowledge, how should we justify our belief in Scripture itself? By Scripture, of course! "
Apologists sometimes accept this accusation but then claim this specific premise is exempt by special pleading or the claim that all world views require presuppositions, so they are justified in this presupposition.
Arbitrarily using the Bible
Presuppositional apologetics arbitrarily assumes a particular Bible or a particular interpretation of God. However, this is an unjustified assumption. In the context of this argument, any other concept or book is seemingly as valid as the Bible. Any god or gods could be justified using arguments of this type.
One common move out of this is to defer to divine revelation. This tactic abandons presuppositional apologetics entirely because it uses the Bible or God is axiomatic.
One of the major omission of presuppositional apologetics is that it does not explained how a single holy book or divine entity can provide the necessary basis for justify reason, knowledge or logic. At least some other presuppositions are required to make these intelligible.
Because presuppositionalists believe acceptance of the Bible is primitive, there is some concern about whether or not they can have a non-Biblical justification for accepting the version of the Bible that they do.
The Biblical text has shifted over the years. It is debatable if current form of the Bible are an adequate representation of either the traditions of the early Church or a reasonable representation of the events that they purport to recount. One of the major issues in this case is the concern over the omission of additional sources from the Biblical Canon. Because presuppositionalists are, generally, protestants, there are some concerns about whether the authority of the early Church extended to the inclusion or exclusion of texts from the Bible. While this is generally an argument amongst Christians, who tend to have misgivings about papal authority, there can be a sharp point made by skeptics.
This argument is supposed to put the presuppositionalist in a dilemma: Any reference to the Bible in justifying the use of a particular version of the Bible is question begging and any admission that there is a non-Biblical reason for choosing a particular version of the Bible requires the presuppositionalist to give up the Bible as foundational, as such a justification constitutes an alternate foundation.
Treating synthetic propositions as foundational
Presuppositional apologetics treats a non-tautological synthetic existential claim (i.e. 'God exist' or the Bible) as primitive. It is generally accepted, in logic, that only universal claims (all x are y) and tautological claims (some p is p) can be primitive. Presuppositional apologetics is founded on defining God into existence and dogmatic claims:
- "To be a presuppositionalist is to redefine the world in such a way that you cannot possibly be wrong and then congratulating yourself for being so right. It's not an argument fit for an intelligent honest person. It's an argument fit for a coward."
In modal logic, existential claims about logical possibilities (like 'God exists') are generally believed to be true in at least one possible world and false in at least one other possible world. Because they are generally accepted as being false in some possible world, they are not considered necessary truths. Only necessary truths can be primitive.
The argument is an attempt to prove a matter of fact using only abstract logic, however it is impossible to demonstrate any matter of fact by this method.
The belief in God is considered a primitive by the apologist and therefore not falsifiable. There is no possible argument to change an apologist's mind. It is difficult to claim something is knowledge about reality and at the same for it to be unfalsifiable.
Apologists claim absolute certainty for presuppositionalism, but psychology tells us there humans are always prone to error, both in perception and cognition. Therefore they are making an impossible claim. It is always possible for people to be wrong.
Asserting Christianity is the only coherent view
Some apologists assert that "The Christian worldview alone adequately explains and accounts for the laws of logic."  Even if an apologist refutes the specific world view of their debate opponent, they do not attempt to justify their assertion that all other world views are inadequate. Therefore, this is an unsupported premise.
Biblical disprove of empiricism and science
The Bible makes claims that are empirically falsifiable, and those claims are not verified upon investigation. If presuppositional apologetics are accepted, an implication is the invalidation of empirical methods, which is absurd. This is similar to the issue of whether the Bible produces logical contradictions; in Clarkian presuppositionalism, this is regarded as being a genuine problem.
The argument has a similar problem as the Euthyphro dilemma:
- "Is something reasonable merely because God proclaims it so, or does God proclaim something reasonable because it is? "
God as an explanation for logic
- Main Article: Argument from ignorance
The final step in the persuasive argument is an argument from ignorance and God of the gaps. There may be other justifications for logic that are beyond our current understanding. The argument is reminiscent of the Natural-law argument and "Evolution is false, therefore God exists", which both suffer from the same problem. The apologist still needs to explain how the Bible can justify knowledge without using any other hidden presuppositions, which will be difficult to show.
The explanation also suffers from being a bigger mystery that what is supposedly explains.
In debates, apologists implicit assume that one and only one person has the correct "world view". They attempt to undermine other world views in an attempt to prove their own view. This is a false dichotomy.
It also falsely implies that to make use of logic, we require a "justification". We may assume the pragmatic position that logic is useful and leave it at that.
Self refuting argument
Presuppositions have a place in communication where a sentence's meaning makes implicit references to shared concepts that are often based on experience. In contrast, presuppositional apologetics claim that views that are based on reliance of sensory experience is potentially flawed and only religious scripture/God is sufficient. This negates the apologist's argument since their claim relies on human sensory experience, language, human cognition and further presuppositions to be meaningful and be understood:
- "When language comes into existence, it is a mix of hard wired biology, structures in the brain, observation of the world around us, our ability to reflect on concepts we form. By dismissing naturalistic [communicative] presupposition, in his attempt to give faith based presupposition precedence, Sye cuts away the foundation of Christian suppositionalist superiority and his argument crumbles to dust. "
In other words, assuming a single holy book or God is the sole foundation is not enough to bootstrap or justify knowledge, logic, communication and reason. We require further presuppositions which the apologist has already rejected. As a specific example, even if the Bible is foundationally true, you still need to read it to understand it. Therefore, apologists are also required to assume there is no Descartes' evil demon that confuses our senses and makes us misinterpret the Bible. This is just one of many unstated presuppositions required if the Bible is to be used in the foundation of knowledge. Once all the hidden presuppositions of the presuppositionalist are uncovered, the presuppositionalist is in the same situation as an atheist philosopher; the Bible is then redundant via Occam's razor.
Tu quoque justification
Presuppositional apologetics has criticised atheists for using presuppositions.
- "Because your presuppositions will not allow you to examine without bias the evidence that I present to you for God's existence. [...] Your presupposition is that there is no God; therefore, no matter what I might present to you to show His existence, you must interpret it in a manner consistent with your presupposition: namely, that there is no God. "
Since atheist or perhaps everyone allegedly uses presuppositions, this supposedly justifies presuppositional apologetics. However, this is fallacious because the "presuppositions of atheists" are not relevant to the question of the existence of God. This is a tu quoque argument.
It is also a straw man argument since some atheists allow the possibility of their mind being changed by evidence. Arguably, many atheists "presuppose" skepticism and avoidance of dogmatism. These beliefs can themselves be subjected to skeptical examination. However, skepticism does not preclude belief in God.
It is also false to draw an analogy between skeptical presuppositions and religious presuppositions. Scepticism attempts to minimise assumptions while presuppositionalist believers assume quite a bit! This analogy is similar to the claim that religion is another way of knowing i.e. all belief systems are equally valid. An example of a faulty analogy:
- "Arguments for religions and philosophical systems are arguments for world views. A world view is a general account of all reality, an understanding of the most basic features of the universe. All arguments for the truth of world views (whether religious, philosophical, political, scientific or whatever) must presuppose standards of rationality consistent with those world views. All such arguments, therefore, are circular in a way similar to ours. "
If this conclusion was true, it would only imply that any such "world view" cannot be logically justified and not that presuppositional apologetics is justified. It is possible to live and provisionally believe things without any grand "world view", such as with existentialism or living without any knowledge of philosophy (naive realism).
Justification from personal experience
Some apologists claim that presuppositionalism is supported by divine revelation. This destroys their own argument that Christian presuppositionalism requires no other justification. It also relies on logic to support presuppositionalism, which Van Tillian apologetics says is less fundamental than their presuppositional axiom (God or the Bible).
"I submit that you can't know what is ultimately real without revelation from God. How do I know what is real? The same way that all of you do. Revelation from the God that all of you know exists."
- — Sye Ten Bruggencate 
The argument is therefore abandoned by the apologist as they resort to the argument from personal experience.
Dismissing secular knowledge
- Main Article: Atheists cannot know anything
Apologists such as Sye Ten Bruggencate claim that the possibility that a person is wrong about any or all of their beliefs is equivalent to "knowing nothing".  This whole point by apologists is a red herring since they may destroy their opponents system but they still have not proved the validity of their own view. It is also a tactic to keep skeptics on a defensive footing in debates and prevents proper analysis of the apologist's views. 
Additional concerns about Platonic epistemology
Van Tillian apologetics generally relies on Platonic epistemology.
Criticism from Reformed epistemology
Platonic theory seems to be treating the existence of God as the existence of a category, rather than as the existence of an object (or fact). If we accept that God is a particular "form" in the sense of Platonic epistemology, then there is some concern about whether or not God is actually an instantiation.
For the reformed epistemologists, God must be actual, and it will not do for God to be a general claim which has a number of instantiations. The reformed epistemologists have a concern with the Platonic epistemology that it requires them to create a singular category for God, of which God would be the only member. The concern, here, is that many of the presuppositionalists want God to be, or be indistinguishable from, that category.
The major issue is that Platonic epistemology maintains that categories are objective. This is not something that most epistemologists are willing to commit themselves too, as it makes some serious presuppositions about philosophy of mind which are not accepted in the field. Most epistemologists maintain that, to some degree or another, the categories that exist in logical systems are a cognitive necessity, but not objective. Whether there are any objective category is an open question among philosophers, but most reject the idea that all epistemological categories are objective.
Perceptual categories, like color, are now understood to be incredibly fluid across cultures. This presents a problem, as the property of red-ness is not an objective property of the objective, but a property of the object as it is represented in the brain/mind. The property of the object has to be described differently, because color is too fluid to be used as an objective descriptor.
Most secular epistemologists now reject Platonic epistemology in favor of Kantian or Quine-ian epistemology. Even Cartesian epistemology (despite some of the concerns in cognitive science and some of the infinite regression concerns) is often considered more sound than Platonic epistemology.
List of presuppositional theologians
Notable proponents of presuppositional apologetics include:
- Cornelius Van Til
- Gordon Clark
- Greg Bahnsen
- John Frame
- Rousas John Rushdoony
- Francis Schaeffer
- Douglas Wilson
- Sye Ten Bruggencate
- ↑ 1.0 1.1 1.2 John Frame, Five Views on Apologetics, 2010
- ↑ 
- ↑ Theopedia, Presuppositional apologetics, retrieved 4th July 2014
- ↑ 4.0 4.1 Glenn Hendrickson, Essay: Christianity Explains Logic, April 27, 2010
- ↑ Presuppositional Apologetics Destroyed
- ↑ Karen S, Yes, Another Pre-Sup Counter-Script New and Improved!, February 27, 2014
- ↑ Steve Shives, Five Stupid Things About Presuppositional Apologetics
- ↑ 
- ↑ Philip Rose, How 2 Debate Theist GOTCHA Arguments 4, 2 Jun 2012
- ↑ 
- ↑ 
- ↑ 12.0 12.1 The Refining Reason Debate, May 31st
- ↑ -Sigh- Oh Sye - Can you be Wrong About Everything you Claim to Know?