The next epistemological methodology is rationalism. Of rationalism, Geisler writes, "Rationalism is characterized by its stress on the innate a priori ability of human reason to know truth. Basically, rationalists hold that what is knowable or demonstrable by human reason is true (29)." To the rationalist, the mind takes precedence over experience and the information acquired through the senses as a foundation for truth and knowledge.
In a rationalist methodology, there exists in the mind a number of innate ideas or principles that allow the individual to arrive at an understanding of the universe. These include principles of logic such as the law of noncontradiction. It is from contemplation upon ideas generated through reflection upon such foundational principles that the thinker is able to postulate systems of truth in a manner reminiscent of mathematics and geometry.
For example, in his system, Descartes started from his "cogito, ergo, sum (I think, therefore I am)" as his ability to doubt was the one thing he could not doubt. From here, Descartes built a theistic proof.
Descartes begins this with the admission that, since he lacks knowledge, he is imperfect. However, to realize one is imperfect, one must have knowledge that perfection exists. Yet perfection cannot arise from within the imperfect. Therefore, there must be a perfect mind from which perfection originates and this is God (31).
An apologetic utilizing the rationalist approach possesses a number of strengths as well as drawbacks. As to its strengths, the rationalist method stresses a consistency of reality.
It follows that a rational God would create a universe that regularly operates in accord with verifiable laws that we as His creations would be able to arrive at through deliberative contemplation. As rationalists posit, the mind to an extent must possess some kind of mental architecture to process the jumble of sense experiences the individual is bombarded with almost constantly. Even Scripture indicates that part of man's knowledge regarding God and His character is innate as Romans says that even the Gentiles, who were not formally given the Law in the same direct manner as their Hebrew counterparts, still had many aspects of the Law written upon their hearts.
Despite the strengths of the rationalist approach to apologetics, the methodology is not without drawbacks. The foremost is the acknowledgement that it can be argued that the rationally consistent does not always translate into the realm of necessarily actual and does not provide the bedrock certainty its advocates claim. For example, regarding the ontological argument, Geisler notes, "But it is not logically necessary for a necessary Being to exist anymore than it is for a triangle to exist...But the point here is that there is no purely logical way to eliminate the 'if' (43)."
Of the next religious epistemology, fideism, Geisler writes, "In view of the fact that empiricism led to skepticism...and that rationalism cannot rationally demonstrate its first principles, fideism becomes a more reliable option in religious epistemology. Perhaps there is no rational or evidential way to establish Christianity (47)." Thus fideism holds that truth in religious matters rests on an accepting faith rather than a critical scrutiny.
As with the other methodologies, fideism comes in a variety shades. On its more moderate side, one finds Blaise Pascal. At the more extreme end of the spectrum, one would find the likes of Karl Barth.
As a fideist, one might find Pascal a bit subdued. Though one would assume reason had no place in fideism, Pascal did not dismiss rational appeals outright. He just did not build his foundation or case upon them. Of Pascal's position, Geisler writes, "A proof at best may be the instrument by which God places faith in one's heart (49)."
Thus, the real difference between Pascal and the rationalist was basically a differing estimation in what each thought reason could achieve. To the rationalist, the thinker is able to deduce their way to a logically irrefutable foundation for a belief in God. To Pascal, such proofs were not absolutely conclusive and the chasm separating doubt and certainty had to be crossed by a bridge of faith.
Since at best, in the mind of Pascal, the individual is left with a fifty/fifty chance regarding the existence of God, the matter did not come down to a dispassionate calculation but rather to a matter of personal existential destiny best summarized by his famous wager (49). According to this wager, if the odds as to whether or not God exists are about even, one is better off believing God exists and then be proven wrong since upon death you would merely pass out of existence than to say God does not exist and then be proven wrong upon death as then one would end up in Hell.
At the other end of fideism's spectrum stands the Neo-Orthodox such as Karl Barth. According to Barth, God is "wholly other" in that God can only be known through faith in revelation. Geisler summarizes Barth's position as such: "We do not know the Bible is God's Word by any objective evidence. It is a self-attesting truth (54)." Thus to the Barthian, the accounts contained in the Bible transpired on a plane beyond the parameters of objective, investigative history. One either accepts them by faith or one does not. Therefore, the believer does not have to answer and is immune from those such as the Higher Critics claiming to apply the rigors of scholarship to the scriptural texts in the hopes of either authenticating or discrediting these documents.
As with rationalism, fideism has both strengths and drawbacks. Fideists are to be commended for holding that the God of the Bible is much more than the God of mathematics. Though there is merit in the attempt to prove that belief in God does not violate reason and logic, there is a great danger in reducing God to the level of a distant first cause not all that interested in how human beings live their daily lives. Fidesits are also correct that ultimately, no matter how much evidence one might collect or how many syllogisms one might be able to deduce, one has to make a leap of faith over those gaps of doubt that remain no matter how small they might be.
Yet despite the strength of their methodology, it has shortcomings as well. Foremostly, fideism makes it very difficult to engage in a debate or discussion with someone holding to another worldview if one must accept a comprehensive system of faith solely by faith without evaluating between them with some agreed upon criteria. Geisler writes, "...either a fideist offers a justification for his belief or else he does not. If he does not, then as unjustified belief it has no rightful claim to knowledge (63)."