“”(T)he only proof for the existence of God is that without God you couldn't prove anything.
|—Cornelius Van Til|
Presuppositionalism is a tactic cooked up by Christian apologists when they realized that their old arguments were not working.
More seriously: the apologetic traces its modern origin to Cornelius van Til (1895-1987), and was continued on through his student Greg Bahnsen. Other exponents of the method include John Frame and, much more recently, Sye ten Bruggencate and a veritable detachment of similar "internet apologists" referred to as Sye-clones by their detractors. Ken Ham and Eric Hovind also employ the method as part of their creationist apologetics.
There is a second branch of presuppositionalism which differs from the van Tillian school in taking the Bible as an axiom, started by Gordon Clark; to no one's surprise, there are sometimes bitter disagreements between the two camps, each of which has of course infallibly had the truth revealed to it.
The crux of presuppositionalism is a twofold technique: First, that only the (Reformed, Westminster Confession) Christian theistic worldview can account for logic, morality, science, induction, consciousness itself, and peanut brittle. Second, that all other worldviews are absurd and/or fail to account for these. Presuppositionalists often go further and assert that classical apologetics and evidential apologetics are sinful and blasphemous, as they savor of "autonomy" and make human reason the judge of God's existence.
According to the presuppositionalist, nonbelievers (which term, in their mouth, very often includes everyone from atheists to other Christians), must assert the Reformed/Westminster Confession worldview in order to deny it; essentially, this is an accusation of stealing the concept, asserted by way of any of a number of the Transcendental argument for God family of arguments. Presuppositionalism is an attempt to argue indirectly for God, rather than directly as classicists and evidentialists do, by trying to prove "the impossibility of the contrary," i.e., attempting a reductio ad absurdum on the opponent's worldview via internal critique.
 Form of the argument
The argument goes something like this:
- Old-School Apologist: Ears up, sinners! Here's an argument that God exists.
- Recalcitrant Sinner: That argument's a pile of bunk! Here's why.
- Old-School Apologist: Oh. Drat.
- Presuppositional Apologist: Fear not, lions of Christ; here comes the new broom! Ears up, sinners! You say all the old-school arguments for God's existence are bunk?
- Recalcitrant Sinner: Yep!
- Presuppositional Apologist: Well, your refutations don't hold water, because they're grounded in the false presupposition that God doesn't exist.
- Recalcitrant Sinner: Uh, no, they're not.
- Presuppositional Apologist: They're grounded in a false presupposition, I say! Now if you'd just presuppose that God exists, it's obvious that God exists!
- Recalcitrant Sinner: And you say we use circular logic...
 Extension: transcendental argument for the existence of God
- Presuppositional Apologist: Did you mention logic? Here is something new for you: every time you mention Laws of Logic, morality and science you already presuppose God's existence, because knowledge, logic, morality and science cannot exist without presupposing God.
- Recalcitrant Sinner: That argument's also a pile of bunk! Defining the reference frame for Logic/morality/knowledge/science, even if it presupposes god, does not necessarily imply its existence.
- Presuppositional Apologist: See, you just gave me more proof that God exists because you are using God-created logic, God-created science and God-created morality!
- Recalcitrant Sinner: But if that's true, the exact opposite of what you argue can be constructed using the exact same arguments, which means your argument's a pile of bunk, like I said!
- Presuppositional Apologist: Blasphemer! If God said 2+2=5, then we've got five eyes between us!
- Recalcitrant Sinner: Hello, fellows in white coats? We need you over here pronto.
 Characteristics of the Argument
Sye ten Bruggencate, among others, has said that the purpose of presuppositionalism is not so much to change minds as to shut mouths. Indeed, the argument garners little respect among even conservative Christians. Even William Lane Craig, he of the "self-authenticating witness of the Holy Spirit," has accused the argument of begging the question (which is really not what one would call a glowing recommendation, especially considering the source...). Very few people find presuppositionalism convincing if they are not already believers, in other words.
Because most people have not delved particularly deeply into epistemology, presuppositionalism may catch them off-guard. It is extremely disconcerting; one gets the distinct impression that sleight of hand has been perpetrated but is not able to see where and how. The strength of this argument is that, rather than trying to defeat its opponent in a race, it ties his shoelaces together so that he immediately falls on his face off the starting blocks.
There is thus a heavy element of psychological warfare in presuppositionalism, either of the coarse type evidenced by the Sye-clone brigade (repeated demandings of "could you be wrong about everything you know?!"), or a more subtle but no less infuriating facade of triumphalistic smugness from the slightly higher-caliber users of the method. In either case, what is notable is the lack of argumentation from the presups' side; it's a tar pit of an argument, and attempting to defend one's worldview is futile since, in his own mind, the presupper has already won the debate.
Nevertheless, there are several glaring flaws in the argument. It attempts to smuggle in several assumptions with the hope the opponent won't notice them: chiefly, it is unable to prove that all opposing worldviews are incoherent.
The presuppositionalist will often say "the Bible isn't the evidence, it's the claim," but the Bible is contingent on divine revelation, which itself is contingent on there being a God, not any specific one. Thus, the argument fatally lacks specificity; just substitute Allah for Yahweh and the Koran for the Bible as a counter-argument and the entire debate grinds to a halt. A Deist could also run the argument just as well, and arguably better, since her God communicates through nature, and does not rely on a collection of books full of known contradictions, inaccuracies, and outrages. An atheist could presuppose that consciousness, logic, etc., are simply brute facts, and claim a similar advantage.
Furthermore, one consequence of the transcendental argument family is that logic, knowledge, morality, consciousness, etc., are contingent upon God, can therefore can be altered by him at will and, here's the key, without any of us necessarily knowing it. Van Til himself has said that God can take any fact and put it into a new relation with any other fact. In other words, God can lie, and we may not know when or if he does. This is commonly met by objections that God cannot lie, but 2 Thessalonians 2:11 specifically recounts God sending a "deluding influence" on people for the sole and explicit purpose of making them disbelieve the truth. Note that this is not a "lying spirit," something with agency of its own, but a "deluding influence" direct from God. So from the Bible itself, which the presuppositionalists are starting from, we know that God could lie, can lie, has lied, and very possibly still does lie.
Because they take the Bible as their pre-rational axiomatic concept, then, they have no grounds for assuming the uniformity of nature, their own consciousness, or even their own existence. Of course, this means they also have no grounds for the laws of logic, including the laws of identity and noncontradiction. Therefore, fittingly and poetically, the presuppositionalist is hoist by his own petard, destroyed by the very charges of epistemic guilt he seeks to lay on the opponent. Presuppositionalism is defeated by internal critique and reductio ad absurdum; to even make its argument at all, its proponents must borrow lumber from another worldview.
 Use by creationists
More recently, Creation Ministries International has been holding to the idea of presuppositionalism. In the context of their particular arguments, this means that they have quit insisting that there is any particular evidence in favor of creationism (a necessary position, given that there is none) and started insisting that it is the interpretation of the evidence that the "evolutionists" have wrong, since they presuppose a naturalistic world-view; supposedly, if one interprets the evidence the right way (which involves not only assuming God's existence, but violating Occam's razor every which way to explain away all the contradictions), one will see that it leads undeniably to the Truth™ of God's existence.
Jonathan Sarfati of CMI, in response to a piece on the complexity of the human genome is a proponent of presuppositionalism:
“”Evolution is not based on evidence that speaks for itself; rather, it is a deduction from their own presuppositions—a priori commitments to materialism and rejection of a designer, because they can’t bear a ‘divine foot in the door’. Therefore they have no right to object when Christians start from their own presuppositions ... When the person you talk to on creation insists that you ‘leave the Bible out of it’, they are really saying the deck should be stacked one way.
But then, after insisting that "evolutionists" are not allowed to have the deck stacked their way in an argument, later in the same article he then says that the creationists should be allowed this privilege:
“”We are not merely asking opponents to consider biblical presuppositions as an alternative way of looking at the evidence. Nor are we merely saying that they are ‘nicer’, nor even that they provide a superior framework that better explains the data (although both of these are true as well). Rather, the claim is even stronger: that the biblical framework is the only one that provides the foundation for science, voluntary will, logic and morality.
In short "Their presupposition is wrong because you're not allowed to use presuppositions we dislike. Our presupposition is right because you are required to use presuppositions we approve of".
 See also
- ↑ Michael Martin, Does Induction Presume the Existence of the Christian God? [Online]. Available: 1997 [Accessed May 28, 2014]
- ↑ http://creation.com/presuppositionalism-vs-evidentialism-and-is-the-human-genome-simple