Cornelius Van Til, The Defense of the Faith, 4th ed., p. 279: "Thus the truth of Christianity appears to be the immediately indispensable presupposition of the fruitful study of nature." My gloss:
The fruitful study of nature presupposes the truth of Christianity. It is a fact that we study nature, and it is a fact that our natural-scientific procedures are successful in many ways and in many areas of inquiry. Now what is factual is actual, and what is actual is possible. But how is it possible? What are the conditions of the possibility of our successful understanding of nature and (some of) her laws? We are being told by Van Til that an indispensable and thus necessary condition is the truth of Christianity.
This illustrates one legitimate use of 'presupposition.' Presupposition in this sense relates an activity or procedure to a proposition. To say that activity A presupposes proposition p is to say that A could not be undertaken with the hope of success were p not true.
For example, the procedures of natural science presuppose the intelligibility of nature. We would not seek the laws of planetary motion, for example, if we did not antecedently believe that the motion of the planets was regular and law-like and understandable by us. But IS nature intrinsically intelligible, intelligible an sich? We have good reason to think so given the success of our physics as shown by its technological implementation.
The presupposition of the intelligibility of nature is therefore well-grounded .
We can push our transcendental regress a step further by asking: what does the intelligibility of nature itself presuppose? What are the conditions of the possibility of nature's being understandable by us? What would have to be the case for nature to be intelligible to us? Here are some candidate answers:
A. The intelligibility of nature presupposes the truth of Christianity. (Van Til)
B. The intelligibility of nature presupposes the existence of God. (It is only because a supreme Intelligence created the world that it is intelligible.)
C. The intelligibility of nature presupposes the truth of Kant's transcendental idealism according to which "The understanding is the law-giver of nature."
D. The intelligibility of nature presupposes an immanent order and teleology along the lines of Thomas Nagel's Mind and Cosmos. On Nagel's view, the rational order is self-explanatory, a necessary feature of anything that could count as a cosmos. Nagel views the intelligibility of the world as "itself part of the deepest explanation why things are as they are." (17). Now part of the way things are is that they are understandable by us. Given that the way things are is intelligible, it follows that the intelligibility of the world is self-explanatory or self-grounding. "The intelligibility of the world is no accident." (17) "nature is such as to give rise to conscious beings with minds; and it is such as to be comprehensible to such beings." (17) See my Nagel category for much more on Nagel's book and other works of his.
I myself incline toward (B). (A) entails (B), but I see no reason to accept (A). The sort of bottom-up reasoning that can plausibly justify us in positing God cannot plausibly justify us in positing the God of orthodox Christian theism with all the Reformed add-ons.
The other sense of 'presuppose' is in play here: "I therefore presuppose the Reformed system of doctrine." (Van Til, p. 27) A presupposition in this sense is an assumption that is accepted unconditionally, uncritically, without question.
Bottom-Up and Top-Down
The first sense of presupposition fits with a bottom-up approach. We start with various features of the world we experience and we then ask what makes them possible. We attempt a regress from the given to the hidden. We start with the world, not with God, and we aim to arrive at God. But if we arrive at God in this way, then the properties we will be justified in attributing to God will only be those needed for our explanatory purposes. Those properties are in a certain sense tied to our starting points. For example, one might reason along these lines: the universe is contingent, but its existence is not a brute fact; so it must have a cause external to it. In this way we get to God as First Cause. Or we start from the intelligibility of nature and arrive at God as the supremely intelligent source of the intelligibility we find here below. Supposing we can get to the true God in this way, a God that needn't have caused anything, or sourced the intelligibility of anything distinct from himself, it nonetheless remains the case that the properties of this God will reflect the facts we start with and our need to explain them.
The second sense of presupposition fits with a top-down approach. We start with God, or at least we try to start with God, and then, instead of regressing from the given to the hidden conditions of the possibility of the given, we progress from the hidden to the given. This is possible if the God who is hidden to the natural man with his natural intellect has revealed himself. I understand Van Til to be saying that we know the true God, the God of Abraham, Isaac, and Jacob only because he has revealed himself to us. The revelation that Van Till accepts is the final truth, not only about God, but also about man, and the universe. Since it the revelation of God, it cannot be questioned. We can say that for Van Til, God and his revelation understood along Reformed lines constitute the Absolute Presupposition.
Interim Conclusion
Van Til's bottom-up transcendental argumentation appears to be a sham. Despite appearances, he is not trying to justify belief in the God of orthodox Christian theism by argumentation from given facts (the existence of nature, its order, beauty, and intelligibility) to that which must be presupposed if they are to be so much as possible; he is not trying to justify belief in the Christian God at all. For he just assumes the existence of the Christian God as something that needs no justification and cannot be questioned since it is that without which there would be no questioning or proving or anything else.
With that absolute presupposition in place as his unquestionable starting point, he can then advance, but not justify, claims like (A) above:
A. The intelligibility of nature presupposes the truth of Christianity.
What Van Til is doing in effect is simply presupposing the truth of (A)! What he ought to be doing, however, is giving us a reason to accept (A). It comes as no surprise, then, that Van Til claims that all reasoning is circular reasoning. (123) We will have to examine that claim and Oliphint's defense of it in a separate post.
Van Til just assumes the truth of his worldview and then in effect says: See! I can explain everything, including why there is no neutral ground for the assessment of worldviews, and why people who reject the particulars of my worldview reject them. But this is of no help to someone who sees no reason to accept his worldview in the first place.
Suppose I grant that that sin has noetic consequences. I grant the thesis. But that leaves open the question as what exactly the noetic consequences are. Is it a noetic consequence of sin that I do not accept Van Til's worldview? Or is rather a noetic consequence of sin that Van Til denies that there is a neutral ground for the assessment of worldviews?
Fascinating! More later. And thanks again to Dave Bagwill for inspiring me to get going on this.
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