In this brief post, I will address four arguments made by presuppositionalists. I will contend, that all four are left unsupported by the proponents of this argument.
Greg Bahnsen writes, "In various forms, the fundamental argument advanced by the Christian apologist is that the Christian worldview is true because of the impossibility of the contrary."
Bahnsen believes there are only two worldviews, the Christian worldview and the non-Christian worldview. He believes that the Christian worldview can be proven true because all other worldviews are contradictory and cannot make sense of logic, science, or ethics. He writes, "It is the Christian's contention that all non-Christian worldviews are beset with internal contradictions, as well as with beliefs which do not render logic, science or ethics intelligible."
Bahnsen believes that only one of these "two" worldviews (i.e. the Christian worldview or the non-Christian worldview) can be "intellectually justified." He writes, "Whose perspective is intellectually justified, the Christian's or the non-Christian's?" (emphasis added) Going back to his contention that the Christian worldview is correct because of the impossibility of the contrary, we can formalize this argument in a disjunctive syllogism.
Q v P
So that, "The Christian worldview is true or the non-Christian worldview is true. The non-Christian worldview is not true, therefore the Christian worldview is true."
Given the premises, the argument is valid. It is up to the person making the "contention," however, to support the premises.
First, then, one must support the claim that the first premise is correct. It must be shown that only one worldview can be true and the other false.
This premise could be easily established if the Christian worldview merely stated that all other worldviews are false. If this was the Christian worldview, then if another worldview could be true alongside of the Christian worldview, the Christian worldview would then be false and the first premise would hold.
So, easy enough, right? Just show that the Christian worldview states that it and only it is the true worldview.
But how is this proven? By reference to the Christian Bible? Well, that assumes (1) that the Christian Bible is a unified body of literature that says only one thing about this subject, and (2) that the Christian worldview is beholden to the Bible in the first place for definition of its worldview.
The first assumption may be easily proven. I can't think of any support off hand for the idea that the Christian Bible is anything but hostile to other worldviews (except, perhaps, Jesus' statement in Luke 9:50 ". . .for whoever is not against you is for you." but this is questionable, at best).
The second assumption, however, is not so easily demonstrated. How can it be proven that the Christian worldview is beholden to the Bible for its definition of its worldview. Many people who claim to be Christians do not believe this. They believe that they receive messages from God that tell them how to live. Others believe that the Bible is simply a human record of God's interactions with humanity and that their own interactions with God shape their worldview, not the recorded interactions of others long ago.
Must an unbeliever choose sides in this internal debate? When the presuppositionalist tells us that only one worldview can be true, must we believe them and disbelieve others who also say they are Christians but who claim that more than one worldview can be true at the same time?
This dispute may be a little easier to resolve between certain atheists and Christian theists. Most atheists believe the Christian God does not, and never did, exist. If an atheist has a materialist/naturalist/physicalist worldview, part of which says the Christian God does not, and never did, exist, one can justify the first premise of this disjunctive syllogism by reference to theistic beliefs.
The second premise of this argument, however, is that it is not the case that any non-Christian worldview is true. This is more difficult to support.
As I see it, presuppositionalists use three arguments to support their assertion that all non-Christian worldviews are not true.
Presuppositionalists use the transcendental argument for the existence of God (TAG). Bahnsen writes that if "predication, reason, explanation, interpretation, learning, certainty, universals, possibility, cause, substance, being, or purpose, counting, coherence, unity, or system in experience or in a conception of a 'universe,' logic, individuating of facts, unchanging 'natures' or laws in a chance universe, uniformity, science, connecting logic and facts or predication to reality, avoiding contradictions, avoiding the irrationalism or scepticism which arise from the tension between knowing discursively and knowing-asystematic, etc," are possible, then God exists. These are possible; therefore God exists.
Though, I think the second premise of this might be harder to justify than many presuppositionalists admit (these are some pretty weighty philosophical questions), I want to concentrate on the justification of the first premise.
How does the presuppositionalist support the assertion that the existence of any of the concepts mentioned above necessitates the existence of the Christian God?
The only thing I've seen from presuppositionalists is a slight-of-hand trick. Instead of justifying their own assertion, they demand that their opponent prove it wrong. Instead of supporting their assertion, they ask something like, "Show me how universal laws of logic (or any of the other concepts listed above) can exist in the non-Christian worldview?"
This, however, is not a support of their assertion. It is, instead, the introduction of a new argument. It is an implied argument, that I haven't seen explicitly stated, but it is present in almost every presuppositionalist argument I am aware of.
This implied argument can be stated formally.
E = the predication "cannot account for everything that exists"
T = true
n = all non-Christian worldviews
Verbally, this implied argument states, "For any worldview, if that worldview cannot account for everything that exists, then that worldview is not true. All non-Christian worldviews cannot account for everything that exists, therefore all non-Christian worldviews are not true."
The first premise of this may well be true enough. One would think that a "true" worldview could account for everything that exists.
It is the second premise, however, that the presuppositionalists must support. How do they do that? How do they show that all non-Christian worldviews do not account for everything that exists?
To actually "prove" this, the presuppositionalists would have to prove a non-tautological universal negative. They would have to demonstrate that no existing or possible non-Christian worldview can account for everything that exists.
I would be very interested to hear support for this one. I, personally, don't think it would be possible.
At this point, though, the presuppositionalists that I am aware of pull another trick. They form a new argument that they would never voice, but quietly assume.
This new argument goes like this--
P1: If a non-Christian debate opponent cannot account for all that exists in terms of his or her worldview, then that non-Christian worldview is not true.
P2: This non-Christian debate opponent cannot account for all that exists in terms of his or her worldview.
C: Therefore that non-Christian worldview is not true.
Here, P1 must be justified. How is it the case that a worldview is not true just because a particular proponent of that worldview cannot account for everything that exists? The non-Christian opponent's ignorance does not invalidate the worldview he or she may hold to. There might be a way to account for those concepts that the non-Christian debate opponent is simply unaware of.
To hold this argument is to hold an ad hominem fallacy. It says that a person's belief is not true because of the person's inability to demonstrate it. [An equivalent argument would be, "My old pastor couldn't justify the existence of evil in the universe given an all-wise, all-powerful, benevolent, free God. Therefore, there is no way to justify this reality."]
This is the lack of support and trickery that I have observed in presuppositionalists.
First, they cannot, in every case, justify their claim that only one worldview can be true. In cases where they can justify that claim (as mentioned above), they cannot support the claim that all non-Christian worldviews are not true.
Second, in the argument that is meant to support the claim that all non-Christian worldviews are not true (i.e. TAG), they cannot support their first premise that the existence of logic (and the other list of concepts above) demands the existence of the Christian God.
Third, in an attempt to support the claim that all non-Christian worldviews are not true, they adopt an argument that states that a worldview that cannot explain everything that exists is not true. While this may well be the case, they cannot support the second premise of that argument that all non-Christian worldviews cannot account for everything that exists.
Fourth, in attempting to support the premise that all non-Christian worldviews cannot account for everything that exists, they assume an argument that states that if "a non-Christian debate opponent cannot account for all that exists in terms of his or her worldview, then that non-Christian worldview is not true." This argument, however, commits a fallacy (i.e. ad hominem).
We see, then, that the presuppositionalist argument is smoke and mirrors. It has been successful in the past because it takes the presuppositionalists' opponents by surprise. If the argument has proven anything, it proves that there are some tough questions in philosophy.
The presuppositionalist thinks that s/he can easily answer any of the difficulties of justifying basic beliefs. The word "God" is invoked like some kind of magical, cure-all elixir. As a team-member here similarly stated, Why is the sky blue? God. Why are bumble-bees yellow and black? God. Why do babies die? God. How can I prove there are other minds? God. How did the universe get here? God. How can a universal exist? God.
That word just fills every gap. You can squeeze it anywhere. The presuppositionalists have a ready answer for problems in philosophy. It's "God."
"What does that mean, though? Define God for me."
"God is powerful."
"Powerful like a truck?"
"No, powerful in a way that you have never experienced. Powerful in a way that you cannot imagine."
"Then what does this tell me about your God?"
"God is benevolent."
"You mean benevolent like volunteers for Doctors without Borders? He heals everyone he can?"
"No, God has actually ordered people to kill children and infants, donkeys and cattle. He is 'benevolent' in a way beyond your understanding."
"Then what does this tell me about your God?"
". . ."
Gees, that word "God" is a convenient bugger though, isn't it? You don't even have to define it intelligbly and you can use it to explain any problem in the world!
Come on, presuppositionalists! There is a reason that your view is ignored by so many. The argument is so full of holes, Swiss cheese is jealous.