The Possibility of Argument
When the Christian and non-Christian argue with one another they will both seek to be coherent in their use of premises that are true. Yet neither one will be able to prove the truth of each and every premise used, for that would lead to an infinite regress and make argument impossible (since it could never get started).
Every argument must begin with some foundational, unproved premises. What sort of premises must these be? In the case of the allegedly self-evident premises one disputer can always claim that the premise is not so self-evident to him. Analytic propositions fail to give any substance to the debate.
Protocol statements need to be accompanied with a more ultimate outlook if they are going to be suitable for deductive reasoning or inductive relating. Inductive arguments are always inconclusive, being subjectively evaluated for their strength. A person may be persuaded by an inductive argument, but what he has thereby is personal belief, not knowledge.
There is always some doubt as to whether the person was persuaded by the truth of the argument or by circumstantial conditions. Even if the initial unproved premises in an argument could be agreed upon by the disputants, when subsequent demonstration disproves one disputant’s position he could take this as evidence that they did not mean the same thing after all by those initial premises.
This is only to say that unless an absolute authority guarantees the truth of initial premises, one disputant can always refuse to be moved by the argument of the other (and with cogent reasons for his stubbornness). In mundane matters men can often agree on initial premises and pursue genuine argument (based on the authority inherent in their personal agreement at the outset).
But an authoritative revelation of the truth is the only basis for premises in an argument over ultimate issues, premises that can be used to drive an opponent from his position. If a theological argument is going to be a genuine argument and not a mere exercise in persuasion tactics, then initial truth must be supplied from an authoritative source.
Should any disputant question how this authority is known to be genuinely authoritative he has failed to recognize the meaning of “authority.” If the authority depended upon some proof of its authoritative status in order that it be acknowledged as the authority, then it would cease to be the final authority.
So then, if an argument is going to constitute a genuine exchange of ideas and legitimate debate, the two opponents must meet on common ground. If disputants do not use the same initial premises that are known to be true, then nothing is “proven.” But we could never know whether two opponents were really using the same foundational premises without a revelation of that fact from One who knows the truth about every situation.
In Romans 1 we read that all men have a clear revelation of God that they seek to misuse and hold down. As seen above, only this inner conviction of God’s existence provides a basis for knowledge of any sort. So this knowledge must be presupposed in order for any argument to take place. Since all men have this knowledge of God (whether they admit it or not) argumentation is possible.
No one could intend to convince his opponent of the truth without the conviction that each of them shared an initially true premise; this conviction can be based only on a word from God. When the non-Christian rejects the revelation of God and holds to a secular cosmology, anthropology, etc., he has no reason to suppose that contact with another mind on any common ground is possible.
If argumentation is going to be possible we need not just any presupposition, but we require clearly revealed and universally necessary ones—presuppositions that Scripture declares God has provided all men.
Here then is the logical oddity of arguments between skeptics and believers. Only if Christianity is true when it claims that all men have a presupposed knowledge of God can there be any common ground on which to maintain an argument at all, and only if God provides the authoritative beginning premise in an argument can the non-Christian ever hope to do more than merely persuade (in an irrational or emotive fashion).
No matter what type of argument is carried on and no matter what type of attack is argumentatively directed against Christianity, they must all presuppose the truth of Christianity if they purpose to be genuine arguments.
The only point of contact between any skeptic and believer who argue with each other must be the truth that the non-Christian is attempting to disprove! He does in fact presuppose this truth but will not acknowledge it (because of his depraved mind). Nevertheless, all genuine argumentation and the attempt to prove a truth presupposes Christianity.
To the degree that the unbeliever has any knowledge at all he is dependent upon the revelation of God, even though he may outwardly repudiate this revelation. This knowledge, which God commonly and graciously allows those who disobey Him, makes it possible for them to argue. The non-Christian, while recognizing the necessity of common presuppositions for argumentation, cannot be assured of them on his own autonomous basis nor can he supply unquestionable axioms that all men know and use.
Only the Christian, depending upon the verbal revelation of God, can be assured that God has revealed certain unquestionable truths to all men in all ages. This revelation given to all men provides the necessary point of contact for an argument between two men. Without it, disputants would be incapable of proving anything, being adrift without a common foundation.
Because the unbeliever will outwardly denounce the truths that Scripture declares God has revealed to all men, truths that are necessary for all science and philosophy, the Christian apologist must not carry on his dispute with the unbeliever on the unbeliever’s own terms or opinion of himself.
Common ground cannot be found at this level. The apologist must appeal to the truth that the unbeliever suppresses (yet utilizes in order to arrive at truth). On the level of outward profession there is antithesis in the presuppositions used by the Christian and the non-Christian, but in their “heart of hearts” all men know the truth about God—for God has Himself shown it to them.
Argument will be possible on this level only. It is only because the unbeliever is not true to his professed position but unconsciously draws upon his “ignorant” beliefs that argument can be exercised between him and a believer.
Hence the Christian apologist should seek to lay bare the character of those presuppositions on which the non-Christian operates when arguing against the faith, demonstrate their self-vitiating quality, and then show the suppressed beliefs that make the unbeliever’s formal reasoning and knowledge possible and that offer common ground for legitimate argumentation.
Autonomous reasoning, with its inherent irrationalism, rather than presuppositional apologetics, makes common ground and argument impossible. The apologetical endeavor is salvaged by a presuppositional approach to the unbeliever, for it allows for genuine and purposed argumentation between them.
The Possibility of Argument
Bahnsen, G. L. (2008). Presuppositional Apologetics: Stated and Defended (J. McDurmon, Ed.) (287). Powder Springs, GA;Nacogdoches, TX: American Vision;Covenant Media Press.