Can Faith and Reason Contradict Each Other?

A Common Assumption

Ask most people today how faith and reason relate, and they will describe a conflict. Reason deals with evidence and proof; faith is what you fall back on when evidence runs out. On this view, the more you think, the less you believe.

The Catholic Church rejects this picture completely. She teaches that faith and reason are not rivals but partners, and that a real conflict between them is impossible. Pope St John Paul II opened his encyclical Fides et Ratio (1998) with a famous image: faith and reason are “like two wings on which the human spirit rises to the contemplation of truth.”

One Source of Truth

The basic reason is simple. Truth is one, because God is one.

God is the author of the natural world, which reason investigates. He is also the author of revelation, which faith receives. He cannot contradict Himself. So what we know by reason and what we believe by faith cannot ultimately conflict.

The First Vatican Council put it plainly in its constitution Dei Filius (1870): “Even though faith is above reason, there can never be any real disagreement between faith and reason, since it is the same God who reveals mysteries and infuses faith, and who has endowed the human mind with the light of reason” (CCC 159).

If an apparent conflict arises, then something has gone wrong. Either the teaching of the faith has been misunderstood, or reason has reached a conclusion it has not actually proved.

Two Orders of Knowledge

The same Council distinguished two ways of knowing.

By reason, we can know a great deal: the natural world, mathematics, history, and even some truths about God. The Church teaches that God’s existence can be known with certainty by the natural light of reason from created things (CCC 36). St Paul says the same: God’s “invisible nature, namely, His eternal power and deity, has been clearly perceived in the things that have been made” (Romans 1:20).

By faith, we know truths that reason could never reach by itself: that God is a Trinity, that the Son became man, that the bread at Mass becomes Christ’s Body. These are not irrational. They are above reason, not against it.

St Thomas Aquinas called the truths about God that reason can reach the preambles of faith. They prepare the way. Faith builds on them, as grace builds on nature.

Two Errors

The Church has condemned two opposite mistakes.

Rationalism says that reason alone is the measure of truth, so whatever reason cannot prove must be rejected. It shrinks reality to what fits inside our heads. It cannot account for the most important things in life, which we know by trusting others: that our parents love us, that history happened, that a friend is honest.

Fideism says that faith needs no support from reason at all, and that reason is useless or even dangerous in matters of religion. In the nineteenth century the Church required fideist writers to accept that reason can know God’s existence and the credibility of revelation. Faith without reason, John Paul II wrote, risks becoming “myth or superstition” (Fides et Ratio 48).

The early writer Tertullian is often quoted on the fideist side: “What has Athens to do with Jerusalem?” But the main stream of the tradition went the other way. St Augustine wrote, “Believe so that you may understand.” St Anselm described theology as “faith seeking understanding.” Faith does not stop thinking. It gives thinking more to work on.

Faith Helps Reason

The relationship runs both ways. Reason supports faith, and faith also helps reason.

Faith frees reason from errors it might easily fall into. Many truths that reason can in principle know, such as the existence of one God or the immortality of the soul, are in practice reached by few people, slowly, and mixed with error. Revelation makes them known to everyone, clearly (CCC 38).

Faith also widens reason’s horizons. It encourages the mind to ask the biggest questions, and it insists that the world is intelligible because it was made by a rational God. Historians of science have long debated how much the Christian conviction that nature has an orderly Creator helped modern science to arise in Christian Europe. Many of its pioneers, from Copernicus to the priest-scientist Georges Lemaître, who first proposed the Big Bang theory, were believers.

What About Galileo?

The Galileo affair of the seventeenth century is the standard example offered of the Church against science. It is worth a brief look.

Galileo was condemned in 1633 for teaching that the earth moves around the sun as a proven fact. The case was a real failure by Church officials, who treated a scientific question as a matter of faith. St John Paul II acknowledged this publicly in 1992.

But the lesson the Church draws is the very principle above. The theologians who condemned Galileo misread Scripture, treating poetic descriptions of the sun’s movement as astronomy. Galileo himself quoted a cardinal of his day: the Holy Spirit intends to teach us how to go to heaven, not how the heavens go. Had that principle been applied, there would have been no conflict.

When They Seem to Clash

What should a believer do when a scientific or philosophical claim seems to contradict the faith?

First, check what the faith actually teaches. Many supposed conflicts dissolve when the Church’s teaching is properly understood: the age of the universe, for instance, is not a matter of faith.

Second, check what reason has actually proved. Science advances by revising its theories. A hypothesis is not a demonstration, and some claims made in the name of science are really philosophical assumptions, such as the claim that only material things exist.

Third, be patient. The Church has lived through many apparent conflicts. Again and again, deeper understanding on both sides has shown that the truth is one.

Thinking as an Act of Faith

For a Catholic, honest thinking is never a threat to faith. It is a way of honouring the God who gave us minds. The Church has founded universities, preserved ancient learning, and produced some of history’s greatest philosophers precisely because she believes this.

As the Second Vatican Council put it, “methodical research in all branches of knowledge, provided it is carried out in a truly scientific manner and does not override moral laws, can never conflict with the faith, because the things of the world and the things of faith derive from the same God” (Gaudium et Spes 36; CCC 159).

For the full text of the First Vatican Council’s teaching, see Dei Filius on our theology site.