Bahnsen is again simultaneously drawing the line too narrowly, and also missing the import of Clark’s manner. He says that Clark seems to give Collingwood to much credit, because he undertakes only to correct “some” of his views, and says that Collingwood “almost” makes history impossible. Clark’s language is opposed to what Bahnsen thinks is adequate, which would be complete undermining of Collingwood’s position.
However, to be entirely accurate, a complete undermining would require every point of Collingwood’s error to be refuted. Even Bahnsen does not attempt such a level of criticism. But even if Bahnsen means that Clark should always present his apologetic as a complete undermining of the opponent’s position, that conclusion seems to me to be a non-sequitur. Bahnsen has already agreed with several Clark quotes, one of which affirms that unbelievers are not thoroughly consistent in their rebellion, meaning that on some points there is psychological agreement, which forms a point of contact in discoursing with unbelievers. What else is Clark doing in acknowledging Collingwood’s ostensible value while undermining what point shall sufficiently reduce his main theory to absurdity? What Bahnsen sees as an insuperable flaw appears to be rather an application of the psychological or ontological point of contact.
The criteria that Bahnsen appears to be applying to Clark would similarly undermine his own approach to other unbelievers. If Bahnsen wanted to be thoroughgoing in his epistemic criticism of unbelievers, he could not assent to any single proposition they stated because it would rest upon an undisclosed and contradictory presupposition that Bahnsen would be disposed to point out in every case. Yet, when Bahnsen debates with Stein, for example, he does not repeatedly tell Stein that this or that argument is invalid precisely because he does not presuppose God. Rather, he deals with subsequent levels of logical analysis, which set up his larger, or more basic criticism.
Clark’s method is no different with Collingwood. At the close of the chapter from which Bahnsen draws his quote, Clark concludes his criticism with what one would think even Bahnsen would find admirable:
But note well, that if Finley and Collingwood rule out faith and make claims to mathematical certainty, history vanishes. Scientific history, autonomous history, certain history is a chimera. One accepts testimony or he does not. The choice is between faith and nothing. (p. 209 in the 1994 edition)
And because Collingwood’s position necessarily excludes such claims to faith, the critique is a reductio ad absurdum that clears the floor for a sound Christian construction to be built.
The last portion of this section of Bahnsen's critique of Clark addresses the concern that Clark posits the laws of logic prior to Scripture. Since he promises to address this error later in the chapter, I'll wait to deal with it in full. However, as a preliminary remark, I think Bahnsen is creating a false dilemma. Clark's assertions about the laws of logic are talking about their instrumental value for our thinking, but even if Clark were using them as a more basic principle, he would argue that the laws of logic are an expression of God Himself, which we can only know as such from Scripture. Thus, he argues from the laws of logic because he recognizes these as something unbelievers will be willing to engage whereas they would not understand the presupposition of Scripture as valid without having first removed the alternatives the falsely believe to be valid.
The difference between Bahnsen and Clark here is not substantive.