Rationalism is the dependence on reason alone, apart from faith, for one’s belief system. Rationalism, by depending on reason alone, has no place for beliefs based on Divine Revelation or any divinely-appointed authority. You might think that all Catholic Christians would reject rationalism, since they profess to belong to the Catholic Faith. But many Catholics have strayed into rationalism, or at least they lean heavily toward that error. Their beliefs depend almost exclusively on their own reasonings. They approve of same-sex marriage, contraception, some abortions, and other ideas contrary to Catholic teaching — because it seems right to them, to their use of reason. They reject the idea that the Church is able to teach infallibly with an ability and an authority that is from God. They reject the infallibility of the Bible, thereby implicitly rejecting its Divine authorship. They reject any Biblical or Church teaching that is contrary to their own reasoning.
Many Catholics have fallen into the error of rationalism. By doing so, they have lost, or are in the process of losing, their faith. Either they no longer believe anything based on faith, or they no longer believe any teaching of faith if it contradicts their own reasoning. So reason reigns supreme in their minds and hearts above faith. Even if the truths taught by faith, along with faith itself, are only reduced in value, so that reason is given the higher place, this too is a form of the error called rationalism.
On the other extreme are certain Catholics who have fallen into the error of fideism, from the Latin meaning “faith-ism”. These persons do not merely give faith a higher place than reason. For while it is an error to put reason above faith, the reverse is not an error. In truth, faith is greater than reason. For we are fallen sinners, and therefore our use of reason is able, and even at times likely, to err. Right reason is inerrant, since reason is a gift from God that is a reflection of the very Nature of God. If a human person reasons correctly (from true premises through a true argument to a conclusion), he arrives at truth without error. But the reason of a fallen sinner, influenced by other sinners and by a sinful society, frequently errs.
The error of faith-ism is not merely giving faith a higher place than reason, but giving reason little or no role in one’s beliefs. Faith must always work with reason, as two wings, as two means — working together — to attain to the truths of faith and morals. Faith and reason must work in harmony, even in matters pertaining to Divine Revelation. For without reason, we cannot understand what is revealed. And even when a revealed truth is beyond complete human comprehension, it is never beyond the apprehension (partial comprehension) of reason. We are made in the image of God by being given both free will and reason. Blind fideism is not the obedience of faith. What we must seek is an ordered synthesis of faith and reason. For reason is needed by faith, even for belief in God. No one can believe in what he does not at least partially understand.
Faith-ism shows itself in a rejection of theological arguments which use reason to argue to conclusions in matters of faith and morals. Faith-ism rejects the importance of a reasonable theological argument for the understanding of faith. Faith-ism gives little consideration to speculative theology and to any theological opinions contrary to accepted ideas. Faith-ism has little use for open questions and pious opinions.
This type of error shows itself in various ways. Some Catholic authors will ask a question, a legitimate theological question, and then give an answer from a particular Saint or Father or Doctor of the Church. That is a good beginning to a theological discourse. But then there is no discourse. “A Saint said it, so it must be true. End of discussion.” And no theological argument, however well-reasoned and well-founded, is given any weight or consideration. A Saint said it, so it is treated as dogma. This too is the error of faith-ism.
The teachings of the Catholic Church are from one threefold fountain of truth: Sacred Tradition, Sacred Scripture, and the Magisterium. The faithful should learn directly from Sacred Tradition, by use of reason and the virtue of faith, and directly from Sacred Scripture, by the same harmonious synthesis of faith and reason, and from the teachings of the Magisterium. Now it might seem that learning from the teachings of the Magisterium does not require the use of reason, except merely to understand what is said. But this is not the case. Often the magisterial teachings require further consideration, comparison between different magisterial teachings in different documents, interpretation in the light of Tradition and Scripture, and a theological and philosophical argument to reach a conclusion that is not explicitly stated, but is necessarily implied. And whenever the teaching of the Magisterium necessarily implies a conclusion, that conclusion is also a teaching of the Magisterium.
An example of faith-ism: I was arguing with a moderator in a discussion group. I offered two premises, A and B, proposing that each is true based on quotations from magisterial documents. She agreed that these two premises are true, because of the quotes from the Magisterium. Then I offered conclusion C, and I asked if she agreed that conclusion C necessarily follows from A and B. “Yes, I do.” So you believe, then, that conclusion C is true? “No, I do not. You didn’t offer a quote from a magisterial document to prove that conclusion. And I can’t trust my own reason.” That is faith-ism in action. You can’t trust your own reason, even if you are reasoning from the truths taught by the Magisterium? But reason is a gift from God. The Catholic Faith is based on faith and reason, not faith alone, and not reason alone.
Something similar happens when I pose an argument to one person or another online, arguing from the truths of Sacred Scripture. The conclusion is rejected, not because the person disagrees with the premise or with the way the argument unfolds. Instead, the objection is: “Your argument is based on your own interpretation of Scripture, and the Church has said we must not engage in the private interpretation of Scripture. Only the Magisterium can interpret Scripture.” Basically, they claim that if we interpret Scripture, using our own reason, then we will go astray, just as the Protestants did, since we cannot trust our own use of reason to understand the Bible. That is the gist of their objection. Of course, the Church has not taught us to avoid interpreting Scripture, just the opposite. We should be constantly learning from Scripture, in the light of Tradition and Magisterium.
What is the source of the ideas held by persons who have fallen into faith-ism? Often, they are not truly believing what the Faith teaches. They refuse to use reason to delve into the teachings of Tradition, Scripture, Magisterium. They despise theological arguments, especially if these are lengthy and involve concepts and terminology with which they are unfamiliar. They have conveniently simplified the Faith, thereby distorting it into something lesser. So their beliefs are a combination of true teachings, their own misunderstandings, pious opinions that they mistake for dogma, doctrinal errors that they somehow picked up along the way and have mistaken for Church teaching, etc. Without the use of reason to continually improve one’s understanding of the Faith, misunderstandings accumulate and coalesce into new and more profound errors.
The most common example of fideism is in the Catholic who, whether liberal or conservative, will not give any weight to any theological argument contrary to his own ideas. Whatever ideas he or she has accepted, correctly or incorrectly, as “Catholic teaching” becomes written in stone. And no amount of reasoning, no theological arguments based on Tradition and Scripture, and no quotations from magisterial documents can change his or her mind. By rejecting the use of reason, faith-ism eventually accumulates so many errors that the individual falls away from the true Faith without even realizing it.
And then these people discover the internet, claim to be teachers of the Faith, and start to spread their errors around the world.