Arguendo

Dr. Darrell Bock 

There’s one thing we haven’t brought up that people listening probably, “Why haven’t you brought this up?” You notice we haven’t done any citation from the Gospel of John, and people go, “Why don’t you do that?” It’s because in an historical Jesus discussion, John is seen as being so explicit that the credibility of what he says is doubted, so we’re dealing with sources that skeptics will recognize, and will play with, and will accept, but they tend to be very slow about anything that’d direct out of the Gospel of John. So we’re working with evidence that a skeptic accepts as a way of thinking about did Jesus make divine claims about himself [transcript].

https://voice.dts.edu/tablepodcast/historical-jesus-divine/

There are several problems with that strategy:

i) It's true that in Christian apologetics we try to find common ground with unbelievers. That's valid up to a point. By the same token, that sometimes includes arguendo reasoning, where we "grant, for the sake of argument," an assumption or objection by the unbeliever. 

That can sometimes be a powerful strategy. It may form the basis of an a fortiori argument. A Christian apologist will play a weaker hand for discussion purposes. If he can win even when assuming that artificial handicap, then it makes his overall case that much stronger when he follows that up by playing a stronger hand. 

ii) It is, however, a problem when apologists fail to upshift. If they succeed in the arguendo stage of the argument, the next logical step is to build on that by bringing other evidence back into the discussion which they temporarily bracketed.

iii) The desire to find common ground should never be a one-sided exercise where the apologist cedes control of the debate to the unbeliever. The onus is not on an apologist to convince the unbeliever. Rather, the onus is on an apologist to provide good reasons for his position, regardless of whether the unbeliever is open to reason and evidence. Unbelievers cannot be allowed to dictate the criteria. The criteria are subject to debate no less than other matters. The rule of evidence predetermine what counts as evidence. So that's a decisive preliminary step.   

iv) If an apologist believes that John's Gospel is historically reliable, then he clearly thinks that's a defensible position–otherwise he wouldn't hold to it. So he should be prepared to defend it. The reasons he has for taking that position himself are reasons he can and should present for why others ought to share his position. 

v) Ironically, there's a sense in which John is easier to defend, on purely evidential grounds, than the Synoptics. There's stronger internal evidence for traditional authorship and/or eyewitness testimony. There's stronger external evidence for traditional authorship. And there's stronger archeological corroboration. 

vi) Although there are passages in Hebrews and the Pauline epistles where the Christology is just as high as the Fourth Gospel, it's important to have the historical grounding in a biography. Even in terms of apologetic strategy, a "skeptic" will dismiss the high Christology of the epistles because the authors had no firsthand knowledge of the historical Jesus. So the Gospel of John provides a key witness to high Christology in the setting of the historical Jesus. Not only is that valuable in its own right, but it forms a bridge between Synoptic Christology and the high Christology Hebrews and some Pauline epistles. (I'm not saying other NT documents have a low Christology. There's a difference between not affirming x and disaffirming x. The former is neutral.)

vii) To take a concrete example, if Christian apologists duck John's Gospel, Muslims will take notice of that. They will infer that Christians lack confidence in John's Gospel.   Likewise, ducking John's Gospel plays into Da Vinci Code suspicions about how orthodox Christology is an artifact of the Nicene Fathers and church councils rather than the NT. So the strategy is counterproductive.