[dlspence_58]

I’ve just started your “Introduction to Logic” course and I’m enjoying it immensely. Taking my time to try and wrap my brain around all of the A, E, I, O, etc. items. My question regards the use of “presupposition” in apologetic circles made popular by Cornelius van Til and Greg Bahnsen. Are you familiar with them and what is your take on “presupposition” as a tool in logic?

Thank you, David Spence

[gerard.casey]

I am familiar with the term ‘presupposition’, David, but not as it’s used by van Til and Bahnsen. That being so, there’s nothing sensible I can say about the use of the term in those contexts.

More generally, the idea of presupposition arise in the context of real-life argument analysis. You are, let us say, reading a scholarly article and you come upon a particular argument. This argument may very well be internally valid but may be sound (i.e. valid with true premises) only upon certain things being taken for granted (presuppositions). Such a strategy is not necessarily unwarranted as we don’t always have time to prove everything to everybody and sometimes we just have to take things for granted. In particular, when our arguments are addressed to particular audiences, we are justified in taking their positions as starting points that do not need to be argued for.

[dlspence_58]

Thank you Dr. Casey for your response. Much appreciated.

[derosa8]

David,

Bahnsen and Van Til famously argued that the Christian God is the necessary presupposition of logic, science, and morality. I’m sure you are aware.

If you have another question, I have studied the issue a bit.

[dlspence_58]

Thank you JohnD. I am reading Bahnsen’s work, “Presuppositional Apologetics”, where he takes the position that to argue/debate with an unbeliever from any other viewpoint than the presupposition of the authority of Scripture is an exercise in futility. Dr. Casey made this point above:

In particular, when our arguments are addressed to particular audiences, we are justified in taking their positions as starting points that do not need to be argued for.

How can we accept the presuppositions of the unbeliever as a starting point, but not accept the presupposotions of the unbeliever as a starting point…that is, only accepting the presupposition of the authority of Scripture as the starting point? I’m interested in yours and Dr. Casey’s response. Thanks.

[gerard.casey]

If I understand what you say about Bahnsen’s work, David, there would appear to be no possibility of a discussion between a believer and an unbeliever. Of course, a person may accept another’s presuppositions ‘for the sake of the argument’ with a view to examining their consistency or the validity of deductions from them without really accepting them. This is common practice. But to require another to commit to your presuppositions which are the very point at issue comes close to begging the question.

One might wonder if, in any rational conversation, there are always some presuppositions or other that are necessarily accepted by both interlocutors (a la Habermas) and if so, whether such commonality is enough to get a genuine conversation up and running.

That being said, exchanges between believers and unbelievers are often a conversation of the deaf (and not only in religious matters but in matters of economics, history, philosophy, climate change, and so on.)

[dlspence_58]

Thank you Dr. Casey. I listened to a debate that Dr. Bahnsen had with Dr. Gordon Stein entitled, “Does God Exist?” (link here: http://www.youtube.com/watch?v=4AvjUZ289L4) Bahnsen argues that the atheist’s presuppositions are not logically coherent and are lacking empirical evidence. Bahnsen admits that the theist can also beg the question in this regard, but states the atheist omits the transcendental and supernatural. In an article, The Crucial Concept of Self-Deception in Presuppositional Apologetics, Bahnse writes, ‘We at times hear people declare “I cannot believe that” (e.g., a close relative has been convicted of a heinous crime), but we all realize that the “cannot” here should be interpreted as “will not”—because one does not want it to be true, cannot emotionally afford to admit it, thinks it is his duty to resist it, or lacks the intellectual energy to rise to the occasion.’
I’d like to hear again from JohnD who says he has studied van Til and Bahnsen.

[derosa8]

Dr. Casey said, “If I understand what you say about Bahnsen’s work, David, there would appear to be no possibility of a discussion between a believer and an unbeliever.”

This is often the first impression that people get when hearing about Van Til’s apologetic method, but it is not what he argued. Van Til argued that the very possibility of discussion between believer and unbeliever is due to the fact that they are both made in the image of God. He called this the “point of contact.” So, Van Til’s method was to argue transcendentally, showing that the unbeliever cannot make sense of reality without the Christian God. To argue transcendentally (as Van Til used it) is to say that something is a necessary precondition of something else.

So, a transcendental argument for the existence of God (TAG) would say that God is the necessary precondition for X. One example of a TAG could be formulated as follows:

(1) If God does not exist, then (universal, immaterial, invariant) laws of logic do not exist.
(2) Laws of logic do exist.
(3) “God does not exist” is false.
(4) Therefore, God exists.

Van Til and Bahnsen would then spend ample time in defending premise (1). However, they would also note that there is not one TAG but many possibilities of formulations for TAG’s. Others commonly used involve induction, science, and morality.

Also, many accuse Van Til of endorsing viciously circular reasoning/argumentation. Here is a link to where a follower of Van Til answers that and other objections:

http://thegospelcoalition.org/blogs/tgc/2012/03/13/answering-objections-to-presuppositionalism/

Hope this is helpful.

[dlspence_58]

Thanks JohnD. I noticed in the debate between Bahnsen and Stein that the issue of immaterialism came up. Bahnsen, of course, affirmed the immateriality of God, which Stein denied. Stein asked Bahnsen if he could think of anything else that was immaterial to which Bahnsen replied, “Yes, the laws of logic!” The audience howled because I think the point was very well made.
Thanks for the link. I will definitely read it and try to absorb some more of this!

[Nismotekk]

Well, I didn’t see an introductions thread, so I figured a thread that is more than five months old is as good a place to start as any!

I’ve been meaning to join Liberty Classroom for some time now, and Dr. Woods 60% off deal was enough to lure me in.

I’ve spent quite a few hours studying the presuppositional argument, or “TAG”. I am intrigued by these sorts of arguments for the existence of God. I’ve also studied other arguments for the existence of God at some length. If nothing more, it’s rather fun to think about.

Some problems I have with TAG.

Firstly, to say that the laws of logic are either immaterial or material is to create a false dichotomy. So, the laws of logic are immaterial? Fine then, please tell me what they are.

Secondly, to say that the laws of logic “exist” is to commit the fallacy of reification. The laws of logic do not exist “out there”, but the objects the laws of logic refer to certainly do. It seems to me that those who argue TAG would rather focus on the concept rather than the referent.

I think Dr. Casey is ultimately right that, when the believer uses this line of reasoning, it creates a gap between the believer and the unbeliever that is unbridgeable. Here is what my mind has come up with in regard to TAG. The believer ultimately thinks that the universe, and all of the laws that govern it, like the laws of logic, physics, etc. must have a prescription, and God is that Grand Prescriber. The unbeliever thinks that the laws of the the universe merely describe how the universe works, and these law do not require a Grand Prescriber.

A person who uses the presuppositional argument often states that the unbeliever must borrow from the believer’s world view to even have a coherent argument. They claim that if not for God, words would not even hold the same meaning from one second to the next. As you can imagine, it can be rather frustrating arguing against TAG when the believer takes this path.

The dichotomy between prescription/description is the fundamental divide between the believer, and the unbeliever. Again, Dr. Casey is right that these arguments are often argued by the deaf.

Myself, if I’m anything, I’m a Spinozan Deist. I just can’t seem to muster the faith that it takes to get me the rest of the way. And, I think that’s what it ultimately comes down to; faith. There’s, nothing wrong with that in my opinion, it’s part of the human experience.

[negligible91]

Hi Chris,
“Firstly, to say that the laws of logic are either immaterial or material is to create a false dichotomy. ”

It doesn’t seem to me this is the case, unless you are speculating some sort of substance that is partially immaterial and partially material. But I don’t think anyone would support the idea that the laws of logic themselves are material in any way, and thus they would have to be immaterial.

What they happen to be beyond that is an entirely different question. It’d be like asking “what category of immaterial are they?” or “what is immaterial?”

[dlspence_58]

Greetings Chris. I didn’t get notification via e-mail that you had posted so sorry I missed it. Please allow me some time to formulate a response to your post. Thanks.

David

[derosa8]

@Chris D,

You said:

[T]o say that the laws of logic are either immaterial or material is to create a false dichotomy. So, the laws of logic are immaterial? Fine then, please tell me what they are.

That is not a false dichotomy; that is a dichotomy. To say the laws of logic are material or immaterial is merely to state that (A) the laws of logic are material or (B) it is not the case that the laws of logic are material. Second, as to what they are, that is not a question universally agreed upon even by those who defend the Christian faith “presuppositionally”. One view is that they are necessary propositions which have their existence in the mind of God. Folks like Bahnsen would be quick to point out that while the Christian can make sense of their immaterial existence, the non-Christian cannot give an account of such universal, invariant, immaterial laws of thought.

You also said:

[T]o say that the laws of logic “exist” is to commit the fallacy of reification. The laws of logic do not exist “out there”, but the objects the laws of logic refer to certainly do. It seems to me that those who argue TAG would rather focus on the concept rather than the referent.

I have a feeling you have trouble affirming the laws of logic exist because you are limiting existence to that which is material. This is evidenced by your comment that they do not exist “out there” since places such as “here” or “there” are appropriate to material objects. Moreover, the meaning of “existence” and what is allowed to “exist” will depend on one’s prior worldview commitments.

Even putting aside existence, Bahsen’s main point still goes through. The laws of logic cannot obtain in this world in the way we all assume they function (i.e. universally and invariantly) unless God exists.

Lastly, what is a Spinozian Deist as opposed to a regular Deist? What brought you to that position? Just curious =)

[dlspence_58]

Thanks John D. Always appreciate your insight. I, too, wondered what a Spinozan Deist is? As I understand Deism it too believes in an immaterial god who, after creating, left things to their own “devices”. Is that a fair assumption?

Further: Even if the overall point of the ‘laws’ of nature is descriptive rather than prescriptive, one is still describing what is. This, of course, does not answer the question of why ‘what is’ is that way and not another, or from whence it has come. Why is there something (that can be described to some level of satisfaction) rather than nothing? Why, (so far) has it only occurred on one planet in one galaxy out of millions and millions of planets and galaxies? These are not questions a merely descriptive view can answer.

[jerry3643]

There’s a great blog called, “Incinerating Presuppositionalism”, in case anyone is interested.

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