If Knowledge Then No God
On my web site www.strongatheism.net, I have an article called "Why Presuppositionalism is Wrong". This article discusses, predictably, why presuppositionalism is wrong. In it, I discuss three arguments that presuppositionalists regularly use to try to justify the impossibility of the contrary - that is, materialism (never mind that not all atheists are materialists). These arguments can be expressed simply as :
(2a) "matter does not contain property X, therefore structures of matter cannot contain property X"
(2b) "your brain came about by an unguided process, therefore you cannot guarantee the truth of X"
(2c) "scientific laws are impossible to prove because they do not attain certainty, therefore they do not justify X"
I address all three types of arguments in the article. However, I recently found a presuppositionalist article by James Anderson called "If Knowledge Then God". I was very delighted to find it, since it is a study of presuppositionalist arguments against the contrary. Seven arguments are presented, three from Plantinga and four from Van Til. I will go through each of these here.
PLANTINGA ARGUMENT #1 : The Evolutionary Argument against Naturalism
This is a variant of (2b) above. I also address the argument specifically in my article "Cutting Off One's Head : The Theological Attack Against Cognition".
PLANTINGA ARGUMENT #2 : The Argument from Proper Function
This is a variant of (2b), clarified by the term "proper function". Basically, Plantinga argues that we can only have knowledge if our cognitive faculties have "a good design plan aimed at true-belief production". It therefore can also be seen as a plain argument from design (pointing out "design" in the human brain and concluding God), and falls under the same problem, including the impossibility to prove that design is specifically needed.
The equivocation between evolved instincts and individual epistemic methods that I discuss in my article can be seen easily here, if you read carefully. Plantinga is quoted saying as a requirement for warrant : "(4) the design plan is a good one: that is, there is a high statistical or objective probability that the belief produced in accordance with the relevant segment of the design plan in that sort of environment is true". But this assumes the absence of moral will, specifically of epistemic methods, hence the equivocation. This is a completely inadequate, invalid way of describing knowledge-acquisition.
PLANTINGA ARGUMENT #3 : The Argument from Anti-Realism
This argument addresses epistemic anti-realism, entailing that reality is somehow subjective, a view which Plantinga rejects as absurd. I agree with him, but I am not an anti-realist.
However, I also reject the claim that a standard of verifiability somehow entails metaphysical subjectivity. Science clearly does not entail metaphysical subjectivity despite its standards of falsifiability. Rather, it acknowledges the objectivity of reality, by demanding that our hypotheses be tested as to whether it conforms to the present or future evidence.
VAN TIL ARGUMENT #1 : The One-Many Argument
The way Anderson presents this is extremely muddled. Basically, he seems to be asking how we account for concept-formation, but with long rambling paragraphs about "unity" and "plurality", and how only Christianity posits that "unity" and "plurality" are "co-ultimate".
Objectivist concept-formation neatly destroys this argument (as far as there is one). To our senses, the existants we perceive exhibit both "unity" and "plurality" - they are all different but they all share basic material properties. Once again, the key here is materialism. The desk in front of me may be different from the pitcher of water, but they both have a shape, dimensions, colour, density, and so on.
The process of measurement-omission consists of realizing, for instance, that there are a number of existants that have a flat surface and drawers, and that they are made to write on, or to support equipment. They may have different sizes, shapes, colours, number of drawers, and so on, but by "omitting" these "measurements", I can integrate all these percepts into the concept "desk". No nonsense about "unity" or "plurality" needed here.
VAN TIL ARGUMENT #2 : The Argument from the Unity of Knowledge
I don't really need to get into the whole argument on this one, since the first premise is bad enough : "(20) If no one has comprehensive knowledge of the universe, then no one can have any knowledge of the universe". Anderson justifies this premise by saying that, without comprehensive knowledge of the universe, a fact could come to light in the future to undermine any of our present knowledge. This is, therefore, a variant of (2c), and just as question-begging - in that atheism or knowledge does not imply belief in certainty at all.
VAN TIL ARGUMENT #3 : The Argument from the Uniformity of Nature
Basically, the so-called "problem of induction". I do intend to write a specific post on this topic eventually, but it looks like I should give the general lines of it now. Basically, it is the theist who has a "problem of induction". Induction is based on the premise that our previous experiences are indicative of future ones. As I said in a previous post, if we accept the existence of miracles, then we must distrust our past experiences, and induction is impossible.
The materialist, on the other hand, has no problem with induction. We know that we can trust our past experiences because we live in a self-contained (i.e. material) universe. There is nothing that can come and muddle the action of natural law on myself or my environment. I am perfectly comfortable knowing that the Sun will rise tomorrow, because the law of gravity will never be suspended. I have no epistemic anxiety whatsoever - but only because I am a materialist.
VAN TIL ARGUMENT #4 : The Argument from Conceptual Schemes
In this argument, it is pointed out that human judgment is shaped by a number of presuppositions such as "logical principles, causal relations, metaphysical necessities, notions of self". Anderson then asks whether 1. we can prove that the universe has such a relational structure and 2. how do we know that we understand the structure of the universe and 3. how do we know that everyone shares this knowledge.
I can start with question 3, since it is ridiculously easy to answer : most of us share the same absolutes because they are part of the structure of our brain, and they are part of the structure of our brain because we could not reason or communicate without them. This is a straightforward consequence of evolutionary adaptation. Even the presuppositionalist shares the same absolutes we do, even if he denies some of them (such as materialism).
How do we know the universe has this relational structure, and how do we know it ? I don't want to take too much space by justifying materialist metaphysics, although if there is any interest, I could address that at another time. All I'll say is that the example of logic is particularly interesting, since Michael Martin has proven with TANG that Christianity is incompatible with any justification for logic. Therefore the presuppositionalist is left empty-handed yet again.