Paul Helm has posted an assessment of presuppositionalism. I’m going to focus on his description and evaluation of “hardline presuppositionalism.”
i) One initial difficulty is that Helm is shadowboxing with invisible opponents. He names no names. He quotes no one. So I don’t know who or what, exactly, he intends to target.
For example, much of what he says would be germane to Clarkian presuppositionalism. But it seems far less relevant to Van Tilian presuppositionalism.
And, of course, there are varieties of Van Tilian presuppositionalism. Is he targeting Van Til’s version? Frame’s? Bahnsen’s? David Byron’s? James Anderson’s? Who and what?
ii) Another problem is that he seems to interpret a presuppositional method in chronological terms. That to reason presuppositionally is to observe a certain sequence in which you treat the Bible as your chronological point of departure.
You begin with Scripture. For unless you first know the Bible, you can’t know anything else.
But if this is what he means, then I think that badly mischaracterizes the position. In Van Tilian apologetics, the Bible is not a chronological starting point, as if it enjoys temporal priority in the “order of knowledge.”
The point, rather, as I understand it, is that biblical revelation is a necessary presupposition in the justification of knowledge.
iii) In addition, I don’t think Van Tilian apologetics primarily concerned with using the Bible itself as a textbook for epistemology.
The point, rather, as I understand it, is that unless the God of the Bible exists, then what we believe and perceive systematically unwarranted. In that event, there is no reason to trust our sensory relays, or cognitive mechanisms, or moral intuitions.
Only God can underwrite knowledge. Unless the Creator and sustainer of the world exists, as identified in Scripture, then we’re condemned to scepticism.
iv) I’m puzzled by the way in which Helm opposes Van Tilian apologetics to “Reformed epistemology.” James Anderson, for one, has argued that we can and should incorporate elements of Plantinga’s epistemology into Van Tilian apologetics.
v) I’d also like to remark on the ambiguities of reliability. For instance, when we say the senses are reliable, what do we mean?
a) Reliability is a relative notion, and on more than one level. Reliable for what?
The eyesight of an eagle is reliable for daytime hunting whereas the eyesight of an owl is reliable for nighttime hunting.
So is the eyesight of an eagle reliable or unreliable? There’s no uniform answer. An eagle’s eyesight is reliable in relation to its internal design and corresponding environment. Reliable during the daytime, but less reliable (or unreliable) at night.
b) Likewise, reliability is also bound up with the principle of design. Is it functioning according to its design specifications? Doing what it was meant to do or made to do?
That’s a teleological concept, and since methodological naturalism banishes teleological explanation from scientific discourse, then an atheistic position like naturalistic evolution can’t evaluate a sensory input in terms of its general (alethic) reliability.
And that, in turn, is a case in which presuppositionalism comes to the fore. Unless God designed our senses, unless God designed our sensory environment, unless God designed each to function in a state of mutual adaptation, then our senses are untrustworthy.
c) Reliability is ambiguous in another respect. Something may be “reliable” in the pragmatic or subjective sense that I rely on it. I have no alternative.
Take a man who’s color-blind. Even though his vision is defective in that respect, he must still rely on his defective vision.
Yet his vision remains defective, and, to that degree, unreliable. There are also situations in which his vision lets him down. Situations in which he needs the benefit of color discrimination. Even though he has to make do with what he’s got, that, of itself, doesn’t vouch for the reliability of his eyesight.
d) Suppose a man is born blind. Suppose, due to technological advances, he is given a pair of artificial eyes. Are these implants reliable?
Well, that depends on whether or not the artificial eyes suffer from a design flaw. If the company which manufactures the artificial eyes has a reputation for shoddy workmanship, then he has reason to suspect the reliability of his artificial vision.
And since he was born blind, he can’t very well compare his artificial vision with his memory of normal vision. So he’s in no position to detect faulty vision.
Yet, in another respect, he is still dependent on his artificial vision. He must rely on his unreliable vision. He has no choice. No fallback.
If, on the other hand, the company is reliable, then he has reason to believe the product is reliable. A reliable source or process produces a reliable product.
And this is, of course, analogous to the evolutionary psychology. Unless God, a God with the attributes accorded him in Scripture, exists, can we trust our minds and senses?
Yes, we still have to take them for granted–even to pose that question–but, then, a man who’s is high on LSD must also take his mind for granted. Delusive or not, that’s the only mind he’s got. Yet, in that diminished condition, his perception of reality amounts to a radical misperception of reality.
That’s the dilemma for naturalism. You have to place unquestioning faith in reason to question reason. But what if your resultant philosophy casts doubt on the reliability of reason?
At that point, should you question your sanity–or question your philosophy?
Presuppositionalism has a confirmatory role. Given the existence of the Biblical God, then we have good reason to trust our minds and senses–within the limits of their design parameters.