Philosophically, for something to be reasonable, it must be rationally coherent. Some would describe reason as an innate power of the human mind that involves understanding, evaluating and constructing concepts and arguments. Therefore, for religious belief to be reasonable, we must evaluate the potential arguments and rational proofs to determine whether religious belief without empirical evidence can be reasonable.
Strong rationalism is the idea that for a religious statement to be propositionally rationally accepted, it must be possible to prove that the belief is true. For example, for a Christian to believe in God due to them having a personal religious experience. A strong rationalist would argue that emotional evidence is not rational and can therefore not support a religious claim. For God to exist from a strong rationalist’s perspective, they must be able to directly see that.
Mathematician W.K Clifford used a parable of an emigrant ship and its owner to demonstrate strong rationalism. The owner of the ship had many doubts that the ship would sink, these doubts are reasonable evidence. He decided to allow the ship to sail with many emigrants aboard it anyway. The ship later sunk, and Clifford explains that the owner was surely guilty for the death of the emigrants, because he had sufficient reasonable evidence that the ship was dangerous.
We can apply Clifford’s logic to religious belief. Surely religious belief seems rationally illogical because there is no evidence to suggest that. However, some religious philosophers, notably John Locke and Thomas Aquinas both believed that Christianity could be rationally defended if approached properly.
However, as religious believers there will be certain prejudices and prior convictions. It is unattainable to remove ourselves of these convictions completely because all knowledge comes to us tainted with prejudice pollution. This itself means that the strong rationalism approach cannot be made to work.
An alternative approach to religious belief is fideism. This is the approach that religious beliefs should not be subject to rational reproach. Fideists believe that everything in life should be built around faith. Faith is one’s ‘ultimate concem’. A fideist Christian does not concern themselves with the idea that their belief may be untrue, instead they claim that they have always had innate knowledge of God and that there is no need to question it. If we attempt to test God using logic and science, we are worshiping reason instead of God himself. The problem is, the rationalist cannot be satisfied by this fideist proposition.
Fideism is flawed and the argument behind it is a fallacy. Fideists propose that rational evaluation of religious belief cannot be done. It is known that fideists seem to be happy to use rational arguments when good ones become available to them. More sophisticated fidesits are not guilty of this act, but there are many who criticize competing belief systems.
For consistency though, this means that other competing belief systems then have the right to point out flaws with fideism. However, fideists cannot counter argue against their convictions because rational evaluation is needed to do this. As stated before, rational evaluation cannot be done so fideists are left with a fallacy.
Due to the inconsistency of fideism and that strong rationalism cannot reveal religious beliefs to be true, we must try another system. Critical rationalism is similar to strong rationalism but does not need a conclusive convincing proof. Religious beliefs can therefore be rationally criticized evaluated and compared. This allows critical rationalism to find the best solution without saying that they can be completely rationally supported. A massive part of critical rationalism is considering the main objections which oppose the belief and why they may be valid.
Critical rationalism can be reached as a middle ground between fideism and strong rationalism. For example, some critical rationalists see no need to offer arguments in favor of their own religious beliefs, which may sound like fideism. However, this opinion is not a fideist one because they recognize that if reasonable objections are made, they must answer them (although they may feel no need to positively support their held belief).
The critical rationalism approach is about evaluating different criticisms for and against beliefs and then deciding whether to adopt certain beliefs. This is a very personal thing, as George Mavrodes (current American philosopher) points out. Mavrodes uses the term “person-relative” to describe the subjectivism of rationality. There are arguments which some find convincing and others of equal intelligence find less so. Mavrodes believes that this varied skew of knowledge comes from our different life experience. Some knowledge can only come from long drawn out (personal) experiences.