Don Collett argues that traditional forms of argument do not do justice to presupposition as a concept. He works from Peter Strawson’s semantic account of presupposition.
According to Strawson, a statement A may be said to presuppose a statement B if B is a necessary precondition of the truth-or-falsity of A. Strawson’s interpretation of the concept of presupposition has been restated in succinct fashion by Bas van Fraassen as follows:
A presupposes B if and only if A is neither true nor false unless B is true.
This may also be stated as follows:
(1) A presupposes B if and only if:
a) if A is true, then B is true.
b) if ~A is true, then B is true.
(Collett, Van Til and Transcendental Argument Revisited, 24-25)
There are potential difficulties with the account of presupposition in question and where Collett goes from here as well but the purpose of this post is not to delve into these potential problems. There is also no effort made to discuss in depth the pragmatic account of presupposition or its consequences especially with respect to covenantal apologetics. Rather I will merely point out that Bahnsen’s understanding of “presupposition” appears to be much more in line with what is known as the pragmatic account of presupposition rather than the semantic account.
There are in philosophy two traditional accounts of presupposition. One is semantic while the other is pragmatic. P.F. Strawson writes, “A statement S presupposes a statement S’ in the sense that the truth of S’ is a precondition of the truth-or falsity of S.” (Strawson, Introduction to Logical Theory, 175) Note then that if S’ is false then S is neither true nor false. The semantic conception of presupposition requires truth-value gaps. On this conception of presupposition not every proposition is true or false. Others have disagreed with the aforementioned account of presupposition and argued for a pragmatic conception instead.
The pragmatic conception does not appeal to truth conditions, but instead contrasts what a speaker presupposes and what that speaker asserts in making an utterance…So conceived, presuppositions are beliefs that the speaker takes for granted; if these beliefs are false, the utterance will be inappropriate in some way, but it does not follow that the sentence uttered lacks a truth-value…it is speakers rather than sentences or statements that have presuppositions; no truth-value gaps are required. (Audi, Cambridge Dictionary of Philosophy, 735)
Collett contends that “[v]an Fraassen’s formulation is helpful” in that “it enables us to articulate more precisely Van Til’s claim that ‘no human being can utter a single syllable, whether in negation or affirmation, unless it were for God’s existence.’” (Collett, Van Til and Transcendental Argument Revisited, 25) Note though that the quote from Van Til is perfectly in line with the pragmatic account of presupposition. Consider then Bahnsen’s definition of presupposition as well.
A “presupposition” is an elementary assumption in one’s reasoning or in the process by which opinions are formed. In this book, a “presupposition” is not just any assumption in an argument, but a personal commitment that is held at the most basic level of one’s network of beliefs. Presuppositions form a wide-ranging, foundational perspective (or starting point) in terms of which everything else is interpreted and evaluated. As such, presuppositions have the greatest authority in one’s thinking, being treated as one’s least negotiable beliefs and being granted the highest immunity to revision. (Bahnsen, Van Til’s Apologetic, 2 n.4)
Both the quote from Van Til and the explicit definition of “presupposition” from Bahnsen evidence that the two thinkers had in mind something much more in line with the pragmatic concept of presupposition rather than what Strawson or van Fraassen have proposed. Both quotations pertain not to whether or not some statement in question is true or false or neither but rather to what is presupposed by a speaker when the statement in question is asserted.
While I understand that Collett is working from a different and more difficult passage from Bahnsen it is inconceivable to me that Bahnsen should have had the aforementioned semantic account of presupposition in mind when commenting upon the formal characteristics of a transcendental argument. Not only does he not mention presupposition in the passage but as quoted above he defines the term itself along pragmatic as opposed to semantic lines and never mentions the semantic account that would be needed to make sense of what he actually writes if Collett’s account is correct. There is certainly nothing wrong with attempting to develop some idea that an author had in mind while writing some text, but it can be problematic to imply that the passage had no discernible meaning prior to its later development. Frankly, I intend to say that Collett has opened up a delightful can of worms that I look forward to sifting through with others in the near future.