There are two tricks of the trade that counter each other. Rationalism and fideism. The first exalts human reason over faith and the second exalts faith over human reason. Both are heresies because a heresy is not the teaching of falsehood, but the emphasis of a truth to the exclusion of other truths.

The rationalist is in the same crazy bin as the follower of scientism. Scientism teaches that there is no other knowledge than that which can be discovered by the scientific method. This is an extension of empiricism which teaches that only that which can be experienced by the physical senses is reliable and sure knowledge. Rationalism is the big sister of these other two. Rationalism teaches that human reason is the sole source of knowledge. If it is unreasonable to the human mind, then it cannot be true. Only that knowledge which can be reached by logical reasoning or intuitive reasoning which is consistently logical is to be allowed.

The popular and debased version of rationalism is the view that something is only true or valid if I can understand it, and the even more debased version is that something is only true or valid if I like it. While there are few people who are pure rationalists, there are huge multitudes who follow the debased and popular versions. These people are the natural cynics, pessimists and deriders. They are the ‘Man from Missouri’ who says, ‘Show Me.’ They are the ones who won’t be fooled by nobody no way nohow. They are C.S.Lewis’ dwarves who won’t be taken in by anyone, and because they will not be taken in they must remain out in the cold.

The fideist, on the other hand, is the apparently religious person who distrusts human reason and opts for faith alone. They see human reason and human learning as inherently untrustworthy enterprises and put their stock completely in miracles, signs and wonders, or in an anti-rationalistic creed (like hyper Calvinism) which they hold to despite all contradictions of common sense, human compassion or human reasoning. When it is pointed out that their position is silly they become self righteous and quote verses about ‘the foolishness of God being wiser than the wisdom of men.’

The fideist distrusts human reason to the extent that he becomes a religious fool, and usually a self righteous and sanctimonious religious fool. A good example of the fidesit is the ‘faith alone’ Protestant, who exalts personal faith over church teachings and the divine institution of the church. Much of Protestantism is inherently fideist. The sola Scriptura (Bible alone) Protestant fundamentalist is also often fideist–holding to patently ridiculous literal understandings of the Scripture which go against all common sense, human reason and even straightforward readings of the Scriptures themselves. Should the Protestant fundamentalist have the ludicrousness of his views pointed out he will retreat to a ‘faith knows better than reason’ position.
While it is easy to blame Protestants for fideism, we have to admit that there are plenty of Catholics who also fall for the fideism heresy. Those Catholics who fall into superstitious practices which go against human reason, those Catholics who hold to extreme traditionalist views and practices that go against common sense, those Catholics who are obsessed with miracles, prophecies from Fatima and such like may fall into fideism…putting more stock in ‘faith experiences’ than human reason.

The fideist is not only found within Christianity. The popular and widespread versions of fideism are superstition, New Age beliefs, self help dogmas and the teachings of self hypnosis gurus and the list goes on…There are all sorts and ways to fall into fideism as well as all sorts and ways of falling into rationalism. Any religious belief or practice which is obviously stupid, irrational or contradictory to human reason tends to fideism.

The Catholic Church teaches that Faith and Reason are beautiful sisters. Nothing in the faith goes against human reason although much in the faith challenges human reason to be expanded and opened up into new perspectives and fresh understandings. The relationship between faith and reason are mutually corrective, mutually challenging, mutually balanced and mutually at the service of each other. Faith encourages and expands reason by insisting that there is ‘more in heaven and earth…than your philosophy has dreamt of’ while Reason balances and corrects superstition, fanaticism, insanity and the sometimes chaotic and bizarre in the practice of faith.

To follow rationalism without faith is to take an easy and lazy option, and to fall into fideism without reason is to do the same. Catholics are called to live by faith, not by sight and this means that we constantly. ‘Believe that we may understand.”