Some Thoughts About the Impossibility of the Contrary


The “Transcendental Argument for God” (TAG) is typically understood as resting upon the “Impossibility of the Contrary.” We may be in a better position apologetically if we think about the Impossibility of the Contrary (IoC) in terms of three aspects of the IoC. These three aspects of the IoC are definition, dogma, and demonstration.


What is the IoC?

“Impossibility” refers to the impossibility of predication upon the presuppositions of some position. We might also take the impossibility in view to refer to the impossibility of the truth of some position, the impossibility of the rationality of some position, the logical impossibility of some position, and so on.

“Contrary” is an informal reference to the “contradictory.” * Contradictory statements cannot both be false at the same time and in the same respect. Hence if a position is false, then its contradictory is true. Or, if a position is true, then its contradictory is false.

When the IoC is defined within the context of the Christian worldview it simply states something to the effect of, “Christianity is true and every other position is false.” Or we might say (even derivatively), “Christianity is rational and every other position is irrational.” And so on and so forth…

Obviously then other worldviews may make claims to their own versions of the IoC. The Christian, however, must always make his apologetic argument along the lines of some form of the IoC. The Christian must do so because Scripture both prescribes and describes this method. Scripture both explicitly and implicitly argues in this manner. To fail to argue using some form of the IoC is to fail to remain consistent with one’s Christian presuppositions and hence to sin. Such failure is indicative of a would-be adoption of the pretended neutrality propagated by many unbelievers and inconsistent Christians alike.


Why believe the IoC?

The reason the Christian adheres to the IoC as explained above is because it has been revealed to us. Christianity is true, and it follows, given the categories of thought provided by Scripture itself, that every other position is necessarily false. Hence the Christian believes in the IoC because God has revealed Christianity to us as true. Additionally, the IoC is taught in Scripture. For example, God claims, “I am the first and I am the last; besides me there is no god. Who is like me? Let him proclaim it. Let him declare and set it before me, since I appointed an ancient people. Let them declare what is to come, and what will happen. Fear not, nor be afraid; have I not told you from of old and declared it? And you are my witnesses! Is there a God besides me? There is no Rock; I know not any.” Isaiah 44:6-8 (ESV) God knows everything. If there is another god, then God would know that there is another god. God does not know that there is another god, therefore there is not another god. In this sense then it is logically impossible that another god exists. There is only one true God, and He is the God of Christian Scripture. It follows that positions which posit some other god are false, or in this case, impossible.

Or consider the claim made concerning, “Christ, in whom are hidden all the treasures of wisdom and knowledge.” Colossians 2:2-3 (ESV) If all of the treasures of wisdom and knowledge are hidden in Christ, then outside of Christ there are no treasures of wisdom and knowledge. All of the treasures of wisdom and knowledge are hidden in Christ. The Christian must affirm this upon the basis of Scripture. Therefore, outside of Christ there are no treasures of wisdom and knowledge. Wisdom and knowledge are impossible on the contradictory position.

Thus Scripture teaches the IoC both implicitly and explicitly and it should be affirmed by believers. We know the IoC because God has revealed it to us in His word.


How do we show the IoC?

The IoC is used in apologetic argumentation through internal critique. The apologist places himself upon the presuppositions of the non-Christian position and attempts to reason consistently with respect to those presuppositions. (Indeed, more consistently than the unbeliever who holds those presuppositions!) The position of the unbeliever is reduced to absurdity or exposed as arbitrary, inconsistent, irrational, and incapable of rendering human experience intelligible in light of its failures with respect to predication. General principles and operative features affirmed by the unbeliever are left unaccounted for within the context of the anti-Christian worldview.


None of what has been stated here is exact, nor is any of it new. We can, however, use this basic outline to begin to think through the various aspects of the IoC in order to clarify and express our position in a sound and persuasive manner. The implications of thinking about the IoC in this way will become apparent when it is applied to various apologetic encounters and popular objections to presuppositional (Covenantal) apologetics in general and TAG in particular.

* A friend wrote to express his concern about this statement. I am no longer persuaded that the puzzling use of “contrary” as opposed to “contradictory” is as easily fixed as what I make it out to be here, and I plan to do further research.


B.C. Askins

“‘Contrary’ is an informal reference to the ‘contradictory.’*”

I echo your friend’s concern. Why not then begin using the phrase “the impossibility of the contradictory,” for the sake of clarity?

As I’m sure you’re aware, the Law of Non-Contradiction (LNC) and the Law of the Excluded Middle (LEM) both apply to contradictories (I am typing/I am not typing), but the LEM does not apply to contraries (I am happy/I am sad).

Surely Bahnsen, et al, weren’t careless in the use of the term, though I don’t recall any explication of this specific distinction in any of the standard VanTillian writings with which I’m familiar.

Given specifically Bahnsen’s argumentation for there being only two worldviews (Christian and non-Christian), one would think he would have chosen to speak of the “impossibility of the contradictory” – however, maybe he chose to use the term “contrary” in order to refer to a refutation of a particular token of that worldview (i.e materialism, monism, Mormonism, etc.), such that the refutation, according to the LEM, might only apply to that particular token, and not necessarily the entire type?

Paul Baird

Interesting explanation of the IoC, Chris.

I’m not convinced that another Theistic worldview would actively advocate a position that all other faith positions are false. Certainly there are many that do but equally there are many for whom the subject doesn’t even come up. Also, I’m not convinced that a hypothetical theism would even need to. In other words you seem to be asserting a requirement that a theism must demonstrate an external as well as an internal integrity, and I think that alot of faiths really do not give a monkeys what the follower of a contrary faith-path thinks ie the need for an justification to something external is not always relevant. It does seem strange that Christianity feels a need to do that.

Equally I’m not convinced by the argument of dogma. In fact I think that this is the weakest part of the IoC. I am going to assume a requirement for the Bible to be literally and inerrantly true. On that basis the Bible has major issues in terms of what it asserts actually happened but also in terms of a lack of third party corroborating evidence, and the abundance of third party evidence that supports complementary histories that simply do not make any sense if the Bible is accurate (eg what was the point of the Mayan or Aztec civilisations, or the Xia and Shang dynasties in China).

“If all of the treasures of wisdom and knowledge are hidden in Christ, then outside of Christ there are no treasures of wisdom and knowledge.”

The civilisations that I’ve cited were able to thrive for quite some time using knowledge that would not have been rooted in either Judaism or Christianity. It cannot be therefore asserted that for them all knowledge was hidden in Christ.

Then there is the obvious problem of a competing dogma that is non-codified but instead is based on more general and localised faith concepts based on the changing environment that that civilisation was living in. Writing and recording information is, relatively speaking, quite a new invention.

The third strand – demonstration, is absurd. Sorry, but it is. Faith-path followers tend to be involved in a two way relationship with their god(s). If the god doesn’t produce the goods after all of the rituals and rites and invocations then that god is going to lose followers pretty quickly.

So if you are going to base the ‘truth’ of a faith-path on the feedback that a follower receives then I think you have some serious problems. The persistence of faiths over prolonged periods of time tends to evidence a positive reinforcement of the relationship between the deity and the believer.

Furthermore if you are also going to assert that the worldview of the non-Christian will be “arbitrary, inconsistent, irrational, and incapable of rendering human experience intelligible in light of its failures with respect to predication” then you will have to explain why so much Christian preaching has failed to live up to those same standards. The best that you will be able to do is to assert that all faiths are equally incapable of rendering human experience intelligible. Christianity did not explain why there is a 11 year solar cycle, or why there was a Great Famine in 1315-1317 and the Little Age Ice in the 1600’s or why El Nino exists and yet isn’t mentioned in the text. No religion does. Yet if you are correct Christianity should.

From all of these points I think that you can guess that I’m not convinced by the IoC.

C.L. Bolt


Right, not all theistic worldviews claim that other faiths are false. Some do, as you mention. I just want to be clear that the IoC could be used by other religions.

Also, something like the IoC might come into play with any truth. Even truths that are typically considered “non-religious” truths, like 2+2=4.

I do not expect non-Christians to be convinced by the IoC as merely Christian dogma. All I am saying there is that the reason Christians believe the IoC is because Scripture teaches it. Certainly you as a non-Christian might raise objections to the truth or reliability of Scripture, but the Christian believes Scripture, and believes the IoC because Scripture teaches it.

The Mayans and Aztecs and the Xia and Shang dynasties in China, along with all other non-Christian societies, were indeed able to thrive apart from professing Christianity. However, they did ultimately rely upon tenets that are only available within the Christian worldview (logic, science, morality, etc.). I am not providing the argument for that here. I am just explaining how the presuppositionalist answers the concern you have raised. We believe that non-Christians do things in practice that they cannot justify in principle. The reason they can do them in practice is because of God’s common grace (God’s favor that He shows to all people everywhere). The reason they cannot justify them in principle is because they suppress the truth of the worldview that allows for things like logic, science, morality, etc. to be possible.

I am not sure I understand your objection about writing being a relatively new invention.

You do not have to apologize for thinking that the “demonstration” aspect of the IoC is absurd, but I am not sure I understand your reason for thinking that, if that is what you were providing right after your statement.

If I read you correctly, then you ask why there is poor preaching; preaching that is arbitrary, inconsistent, irrational, and incapable of rendering human experience intelligible. Or, to make the objection more pointed, why is it that Christians still do wacky stuff? There are many ways to answer that question, but the initial response is that Christians, like everyone else, are sinners. Hence they are not always consistent with even their own worldview. But being capable of accounting for intelligibility because of your worldview, and being incapable of doing things well (like logic, science, morality, etc.) are two different things. In other words, the idea is that only the Christian worldview allows for logic, science, morality, etc. That does not mean that Christians are always logical, scientific, or moral.

If by “Christianity” you mean the Bible, then no of course Christianity did not explain the solar cycle, Great Famine, Ice Age, or El Nino. None of those is mentioned in the Bible. But Christianity is not limited to believing in what the Bible explicitly states. That’s not the presuppositionalist argument at all. Rather, the Christian worldview as a whole is what renders human intelligibility possible. The reason we can know history and science, for example, in order to know the things you mentioned, is because we are God’s creatures in God’s world. The worldview that we derive from Scripture equips us with the metaphysical preconditions (it says what sorts of things are real and not real) and conceptual tools necessary to make sense of the world.

It was not my intention in the post above to convince an atheist that the Christian’s claim of the IoC is true. So I am not surprised that you are not persuaded by the post. I was not trying to persuade you at all. What I am doing is trying to set out the IoC in its three different aspects. I might then return to it and use each of these aspects to respond to objections to the method and argument of covenantal apologetics.

Hope that helps.

Paul Baird

Hi Chris,

“However, they did ultimately rely upon tenets that are only available within the Christian worldview (logic, science, morality, etc.). I am not providing the argument for that here.”

I do hope that is not the get out jail free card “sensus divinitatis” but I think it is. It’s an appalling argument as it is unproveable and unfalsifiable.

I’ll post further comments later.


Hey folks,

Just new to the formal Pre-sup argument, although I at times have used it not know its formal name. My question is or quandary is although IOC proffers itself as a “be all end all” type of declaration based on God is all, and thus what he says goes, and then uses logic to supplement the IOC as evidence. So is then in terms of Evidence, is this a beyond of reasonable doubt sort of thing ? The IOC, seems beyond that.

I come from a evidentialist upbringing, which is exhausting as it seems never ending when discussing the Bible vs other world views, I come up with something, the other person counters with something else…too much. Thats why I am interested in the Van-Til claim of “one and done” witnessing” if you will allow me to characterize it that way. I just don’t think you can do this. Simply because, you are by the non-believers view “creating this God” that can do everything and as Paul says is un-falsifiable…

So perhaps as I read on I will get more confidence in it. I certainly understand how Aristotelian logic favors the Christian worldview, but the atheist says we are adjusting our Lord to fit the logic…any comments would be appreciated.

C.L. Bolt

I don’t understand your question.


I just don’t see where this argument (TAG) is that overwhelming that an atheist has no good rebuttle .. He can just say, “That we christians are shaping God to fit the laws of logic” The atheist can do the same with a can of soda. Not trying to be smart ass, but there is no way to avoid using evidence, which it seems that TAG is being sold as a type of argument that does not need conventinal evidence to prove God..

C.L. Bolt

I am still unsure what you mean by “shaping God to fit the laws of logic,” but I will take a stab at what seems to be your concern.

Let’s say the atheist attempts to rebut the TAGster by claiming that the TAGster has contrived his or her God to provide the necessary preconditions for the intelligibility of logic. It should be pointed out in response that, first, the genesis of the Judeo-Christian concept of God would appear almost wholly irrelevant to any later philosophical concerns regarding logic. Second, the TAGster argues from over two thousand years of biblical, exegetical, and systematic theology grounded in Scripture, which precludes any charges that the TAGster has engaged in ad hoc argumentation. Third, regardless of the motivation for the conceptualization of the Judeo-Christian God, He, granting the TAGster’s argument, fulfills the necessary preconditions for the intelligibility of logic, and alleged rebuttals which appeal to the origins of the concept of God are subject to the genetic fallacy. Fourth, if the atheist is going to reject the Christian worldview, claiming God is posited as an ad hoc explanation for the metaphysical preconditions of logic, etc., then he or she will need an alternative account for the intelligibility of logic.

You offer, as an example of the aforementioned need, a can of soda. The only difficulty is that you do not actually explain what a transcendental argument, from logic, to the metaphysical precondition of a can of soda, actually looks like. Unlike God, a can of soda is an impersonal, contingent entity, and I could see those two attributes of a can of soda dooming its chances as a potential transcendental ground for logic.

Regarding evidence, I am not sure where you got the idea that covenantal/presuppositional apologetics do not use evidence.

Thanks for the clarification, and hope this helps.


Thanks a lot. Your “stab” hit home. Being rather new at apologetics, I need improvement formulating my questions. I am getting some training from Greg Koukl from, and when I came across presuppositional apologetics, I found it very interesting, I am reading a work by Greg Bahnsen (sp) currently. You sound like you have been formally trained in this, thanks for helping me Mr. Bolt.

C.L. Bolt

TAG would be the argument used to show that they were relying upon the Christian worldview.

The sensus divinitatis is not really an argument per se. It is a doctrine about knowledge of God. I disagree that it is unprovable. It could be proven from Scripture (assuming one accepts Scripture as an authority, and I realize you do not). It might also be proven through TAG. It may be unfalsifiable, but it depends upon what you mean by that term. Most people I encounter do not understand the history, meaning, or application of the criterion of falsifiability.

Justin Andrusk

Under the “Demonstration” section it is stated, “The apologist places himself upon the presuppositions of the non-Christian position and attempts to reason consistently with respect to those presuppositions.” I do not think think that the Christian apologist has as a warrant from scripture for this approach. I remember Bahnsen quoting Van Til on this same argument. My concern is that the Christian has to negate what he is trying to prove by attempting to place himself upon the presuppositions of the unbeliever. Do you have an example from scripture where this approach is taken?

C.L. Bolt

First, there is nothing unbiblical about the approach in question. Second, Bahnsen appeals not only to Van Til, but to Scripture as well with respect to the approach in question and argues that Paul takes the approach in question in Acts 17. It is also argued that Proverbs 26.4-5 presents a two-step approach to apologetics involving the aspect of the method you express concerns about. There are other biblical examples provided in the presuppositionalist literature, though I confess I do not have the time to try and remember them at the moment. Third, the Christian does not have to negate anything he is saying in order to use arguendo. I am not sure where you are getting that from. For example, I could make the following argument:

If atheism is true, then there are no objective moral values.
Atheism is true.
Therefore there are no objective moral values.

without negating anything that I believe, say, or do as a believer. I do not take it that atheism is true, nor do I think that objective moral values do not exist. Rather, I am arguing by virtue of a hypothetical. I am placing myself upon that position of atheism *for the sake of argument*. That means, by definition, that I do not necessarily hold that position, and hence I have not negated anything that I am trying to prove.

Scripture is clear that the one who says in his heart that there is no God is a fool, and that his or her reasoning is futile, etc. We demonstrate this through the method of internal critique.

Hope that helps!


I am finishing up my thesis that focuses more on Jesus’ arguments and it’s implication for apologetics. I do think that there are examples of Scripture where we see this method of internal critique…in fact, Chris Bolt do you think that might be something I can work on as an article for In Antithesis?

C.L. Bolt

It sounds like a worthy topic. Send us an abstract etc. per the instructions on the appropriate tab at the top of the site.

Presuppositional Apologetics Links during Feb 2012 « The Domain for Truth

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Throwback this article. It’s a good one.

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I recently started studying presuppositional apologetics and I love it. This article was very useful in helping me understand an integral part of the argumentation. Thanks for writing it!

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