“Foundationalism has been the reigning theory of theories in the West since the high Middle Ages. It can be traced back as far as Aristotle… Aquinas offers one classic version of foundationalism. There is, he said, a body of propositions which can become self-evident to us in our present earthly state. Properly conducted scientific inquiry consists in arriving at other propositions by way of reliable inference from these (demonstration). A few of these (for example, that God exists) can be inferred from propositions knowable to the natural light of reason …within the community of those working in philosophy of knowledge and philosophy of science foundationalism has suffered a series of deadly blows in the last 25 years. To many of those acquainted with the history of this development it now looks all but dead. So it looks to me. Of course, it is always possible that by a feat of prodigious imagination foundationalism can be revitalized. I consider that highly improbable…” (Nicholas Wolterstorff, Reason Within the Bounds of Religion, pp. 26-27).
Long ago Sextus Empiricus put forth the devilish argument that any justification of the value of rational proof would have to be (1) a rational proof and therefore be circular or (2) irrational and therefore of no avail in establishing the rationality of reason. Aristotle in Metaphysics recognized that justificationalism would entail an infinite justificational regression (how do you finally justify something? Is it based on something which is based on something and so on infinitely?).
Reason cannot be (1) proven or (2) falsified without circularity. Notwithstanding the collapse of classical foundationalism in philosophy (3) fideism (reason “based on faith”) or (4) radical suspicion as being prior to or somehow supplanting reason entirely are problematic as well. Let us consider briefly why this is so.
Regarding (1) and (2), any attempt to rationally dislodge or rationally ground reason is ultimately question-begging and therefore self-defeating (arguing against the rationality of argument, or for it; employing logic to refute logic, or to ground logic).
The problem with option (3), the fideist option (reason “based on faith”) is that any presupposition which is held by faith (in the Kierkegaardian sense of a sort of leap) is already tacitly presupposed as “meaningful” as opposed to “meaningless” before one considers whether to affirm it as a presupposition; it is tacitly presupposed as cognitively distinguishable from its own contradictory. Aristotle’s law of non-contradiction affirms something cannot be both A and non-A at the same time and in the same sense. Another way of saying this is that any meaningful act of presupposition tacitly presupposes rationality norms and their justificative decisiveness. So fideism cannot “ground” reason as a presupposition without already employing it to recognize there is even such a thing as a meaningful presupposition. The law of non-contradiction must already be operating prior to any meaningful act of presupposition or else that act of presupposition cannot be meaning-distinguished from it’s contradictory opposite.
(4) Radical Suspicion of reason as such, if deemed cognitively meaningful, encounters a similar difficulty in that any meaningful act of doubt presupposes rationality norms and their justificative decisiveness to demarcate a particular doubt as meaning-distinguishable from its contradictory. Accurately perceiving or describing what such suspicion even is presupposes a successful function of reason. Suspicion concerning the bounds and excesses of rationalism is another question, and something which is indeed not without warrant, but that is a topic for another day. In summary, it is equally problematic, then, to regard reason as (1) demonstrable/grounded (2) falsifiable, (3) fully supplantable by fideism, or (4) amenable to cognitively meaningful radical suspicion as such without its effective operation.
Reason is a gift; it is not a foundation one can construct systematically from the bottom up -a failed program if there ever was one. Yet like mathematics it is, to borrow Nobel Prize winner Eugene Wigner’s description, “unreasonably effective” to a degree that boggles the mind. https://www.dartmouth.edu/~matc/MathDrama/reading/Wigner.htm
Morris Kline, Mathematics: The Loss of Certainty (NY: Oxford University Press, 1980).
On Godel’s Incompleteness Theorem (pertains to all formalized systems / cf. logic): https://katachriston.wordpress.com/2010/12/27/godels-incompleteness-theorem-the-most-important-mathematical-theorem-in-the-twentieth-century/
The Laws of Thought: A Short Historiography of a Paradigm in Transition https://katachriston.wordpress.com/2011/12/16/the-laws-of-thought/
Lewis Carroll’s classic highly entertaining essay “What the Tortoise Said to Achilles” (Mind 4, No. 14 (1895) found here: http://www.ditext.com/carroll/tortoise.html
Munchhausen Trilemma http://en.wikipedia.org/wiki/M%C3%BCnchhausen_trilemma