How does the Church define reason? Does the Catechism of the Catholic Church give a definition? Fides et Ratio did not have a definition even if it is a encyclican on the subject.

I find this a bit strange.

  • See Fides et Ratio #4, which culminates in a definition of "right reason."
    – zippy2006
    Dec 20, 2019 at 3:43
  • @zippy2006 Not quite. In #4.1 is about universal elements of knowledge shared by all humans seek by human driven by wonder upon contemplation of creation, to enrich life. #4.2 is about the fruits of philosophy which can lead to pride; each system should have its own integrity & needs to respect and serve its source (the enquiring human mind). #4.3 is about common principles shared by various philosophical systems in history which should serve as a reference point / universal principles. Once reason can intuit and formulate these and are coherent, then it can be branded "right reason". Dec 20, 2019 at 5:48
  • @zippy2006 So as my answer describes, the church performs an evaluation and provides a criteria, not so much a definition of reason that the OP is seeking. The church is like a doctor who does diagnostics to determine whether reason has been doing well or not based on spiritual principles (the health of the operations of human nature in general). The document is very rich, beautiful, inspiring, while helpful at the same time for Christian philosophers and scholars. Dec 20, 2019 at 5:50
  • No, #4 is talking about reason, which is the "single term that conceals a variety of meanings." Wonder is the Platonic philosophical disposition, systematic thought is the primary product of reason, and "right reason" is the essence and goal of reason. FR #4 is JPII's definition of reason.
    – zippy2006
    Dec 20, 2019 at 16:20
  • @zippy2006 I definitely agree with you that #4 is about reason and ends with the criteria of what reason should be doing when it is philosophizing making the document extremely practical. I think the "single term" in #4.1 refers to philosophy (cf. "the term philosophy means love of wisdom" in #3.1) as #3 talked about how philosophy's goal is to sketch answers to life's questions, thus making human lives more human. Dec 20, 2019 at 20:26

3 Answers 3


It is not for the Catholic Church to define reason, but to teach how reason contributes or hinders our understanding of God, who is critical for our salvation:

  • When a philosophy (or science, which is properly below philosophy) devalues reason too much below what the Scripture or Tradition says, the church will re-establish the existence and competence of human reason. For example, in light of Neural networks and Artificial Intelligence, some scientism position sees human being as nothing more than an animal with an advanced brain that one day can be completely simulated by a machine.
  • On the other hand, when Nietzsche dares people to "grow up" and make their own ethics and values, the Church will step in and say that reason has overstepped its authority because reason cannot supplant the natural law implanted in human conscience by God Himself.

Philosophy is free to define what reason and rationality is as long as certain aspects of human nature as taught by the Church stay intact.

Therefore Fides et Ratio's main purpose is to guide Catholics in the 20th century on how to make use or guard against modern philosophies in connection with applying the church doctrines in a believer's faith life:

  • It is a kind of re-establishing the boundary between the church's domain (charged with guarding the proper use of the revelation from God in Scripture and Tradition) and the philosophy's domain (charged with exploring everything that rationality can discover on its own)
  • It is a guide to reconcile the findings of both domain, because at the end of the day we cannot have parallel but contradictory truths that destroy each other's credibility. There is only a single rationality and a single revelation to resolve a single matter. Faith and Rationality must cooperate harmoniously to determine which sphere has the authority and if there is a conflict, which one takes precedence depending on the matter and the discipline.

Please see an excellent commentary on Fides et Ratio by Prof. Alfred J. Freddoso, a Catholic philosophy professor at Notre Dame who teaches courses on St. Thomas Aquinas as well.


How does the Church define reason?

Catholic Culture gives us a short, but easy definition as to what reason is.


In general, the mind in its function of attaining the truth. Also the basis or evidence used by the mind in its pursuit of truth. It differs from the intellect, whose proper role is to perceive the truth, whether arrived at by a reasoning process or perceived immediately as intuition. Reason, therefore, is a process, where intellect is possession.

The Catholic Encyclopædia gives a much more detailed description as to what reason is.

The closest I can find in the Catechism of the Catholic Church is as follows:

286 Human intelligence is surely already capable of finding a response to the question of origins. The existence of God the Creator can be known with certainty through his works, by the light of human reason, even if this knowledge is often obscured and disfigured by error. This is why faith comes to confirm and enlighten reason in the correct understanding of this truth: "By faith we understand that the world was created by the word of God, so that what is seen was made out of things which do not appear."

  • I just read "In general, the mind in its function of attaining the truth." and I got confused. What is mind?
    – Hank
    Dec 20, 2019 at 9:16

Human reason is what, without divine Revelation, enables us to know that God exists and what His divine attributes are.

Chapter 4 "On Faith and Reason" of the First Vatican Council's Dei Filius describes human reason by contrasting it with knowledge obtained by faith from divine Revelation:

The Catholic Church, with one consent, has also ever held and does hold that there is a twofold order of knowledge distinct both in principle and also in object; in principle, because our knowledge in the one is by natural reason, and in the other by divine faith; in object, because, besides those things to which natural reason can attain, there are proposed to our belief mysteries hidden in God, which, unless divinely revealed, can not be known.

  • I don't think Dei Filius describes human reason, but more describing the limit of its ability in matters of faith. The era of the document was closer to Kant, so the kind of issues it focused on was different than Fides et Ratio. Again, I can see the Church trying to set boundary between the role of reason and the role of faith. Your Catholic Dictionary link however does define reason, but that's not the Church doing it, and is too short and too general to be useful compared to Catholic Encyc. entry. Dec 20, 2019 at 6:01
  • I guess today we have to tell some religious people to use more reason. Then they might understand how Mary can be the Mother of Jesus. Badsics biology shouödn't be that difficult.
    – Hank
    Dec 20, 2019 at 9:21

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