28. The search for truth, of course, is not always so transparent nor does it always produce such results. The natural limitation of reason and the inconstancy of the heart often obscure and distort a person's search. Truth can also drown in a welter of other concerns. People can even run from the truth as soon as they glimpse it because they are afraid of its demands. Yet, for all that they may evade it, the truth still influences life. Life in fact can never be grounded upon doubt, uncertainty or deceit; such an existence would be threatened constantly by fear and anxiety. One may define the human being, therefore, as the one who seeks the truth.

29. It is unthinkable that a search so deeply rooted in human nature would be completely vain and useless. The capacity to search for truth and to pose questions itself implies the rudiments of a response. Human beings would not even begin to search for something of which they knew nothing or for something which they thought was wholly beyond them. Only the sense that they can arrive at an answer leads them to take the first step. This is what normally happens in scientific research. When scientists, following their intuition, set out in search of the logical and verifiable explanation of a phenomenon, they are confident from the first that they will find an answer, and they do not give up in the face of setbacks. They do not judge their original intuition useless simply because they have not reached their goal; rightly enough they will say that they have not yet found a satisfactory answer.

30. It may help, then, to turn briefly to the different modes of truth. Most of them depend upon immediate evidence or are confirmed by experimentation. This is the mode of truth proper to everyday life and to scientific research. At another level we find philosophical truth, attained by means of the speculative powers of the human intellect. Finally, there are religious truths which are to some degree grounded in philosophy, and which we find in the answers which the different religious traditions offer to the ultimate questions.27

The truths of philosophy, it should be said, are not restricted only to the sometimes ephemeral teachings of professional philosophers. All men and women, as I have noted, are in some sense philosophers and have their own philosophical conceptions with which they direct their lives. In one way or other, they shape a comprehensive vision and an answer to the question of life's meaning; and in the light of this they interpret their own life's course and regulate their behaviour. At this point, we may pose the question of the link between, on the one hand, the truths of philosophy and religion and, on the other, the truth revealed in Jesus Christ. But before tackling that question, one last datum of philosophy needs to be weighed.

31. Human beings are not made to live alone. They are born into a family and in a family they grow, eventually entering society through their activity. From birth, therefore, they are immersed in traditions which give them not only a language and a cultural formation but also a range of truths in which they believe almost instinctively. Yet personal growth and maturity imply that these same truths can be cast into doubt and evaluated through a process of critical enquiry. It may be that, after this time of transition, these truths are “recovered” as a result of the experience of life or by dint of further reasoning. Nonetheless, there are in the life of a human being many more truths which are simply believed than truths which are acquired by way of personal verification. Who, for instance, could assess critically the countless scientific findings upon which modern life is based? Who could personally examine the flow of information which comes day after day from all parts of the world and which is generally accepted as true? Who in the end could forge anew the paths of experience and thought which have yielded the treasures of human wisdom and religion? This means that the human being—the one who seeks the truth—is also the one who lives by belief.

32. In believing, we entrust ourselves to the knowledge acquired by other people. This suggests an important tension. On the one hand, the knowledge acquired through belief can seem an imperfect form of knowledge, to be perfected gradually through personal accumulation of evidence; on the other hand, belief is often humanly richer than mere evidence, because it involves an interpersonal relationship and brings into play not only a person's capacity to know but also the deeper capacity to entrust oneself to others, to enter into a relationship with them which is intimate and enduring.

33. Step by step, then, we are assembling the terms of the question. It is the nature of the human being to seek the truth. This search looks not only to the attainment of truths which are partial, empirical or scientific; nor is it only in individual acts of decision-making that people seek the true good. Their search looks towards an ulterior truth which would explain the meaning of life. And it is therefore a search which can reach its end only in reaching the absolute.28 Thanks to the inherent capacities of thought, man is able to encounter and recognize a truth of this kind. Such a truth—vital and necessary as it is for life—is attained not only by way of reason but also through trusting acquiescence to other persons who can guarantee the authenticity and certainty of the truth itself. There is no doubt that the capacity to entrust oneself and one's life to another person and the decision to do so are among the most significant and expressive human acts.

It must not be forgotten that reason too needs to be sustained in all its searching by trusting dialogue and sincere friendship. A climate of suspicion and distrust, which can beset speculative research, ignores the teaching of the ancient philosophers who proposed friendship as one of the most appropriate contexts for sound philosophical enquiry.

From all that I have said to this point it emerges that men and women are on a journey of discovery which is humanly unstoppable—a search for the truth and a search for a person to whom they might entrust themselves. Christian faith comes to meet them, offering the concrete possibility of reaching the goal which they seek. Moving beyond the stage of simple believing, Christian faith immerses human beings in the order of grace, which enables them to share in the mystery of Christ, which in turn offers them a true and coherent knowledge of the Triune God. In Jesus Christ, who is the Truth, faith recognizes the ultimate appeal to humanity, an appeal made in order that what we experience as desire and nostalgia may come to its fulfilment.

34. This truth, which God reveals to us in Jesus Christ, is not opposed to the truths which philosophy perceives. On the contrary, the two modes of knowledge lead to truth in all its fullness. The unity of truth is a fundamental premise of human reasoning, as the principle of non-contradiction makes clear. Revelation renders this unity certain, showing that the God of creation is also the God of salvation history. It is the one and the same God who establishes and guarantees the intelligibility and reasonableness of the natural order of things upon which scientists confidently depend,29 and who reveals himself as the Father of our Lord Jesus Christ. This unity of truth, natural and revealed, is embodied in a living and personal way in Christ, as the Apostle reminds us: “Truth is in Jesus” (cf. Eph 4:21; Col 1:15-20). He is the eternal Word in whom all things were created, and he is the incarnate Word who in his entire person ³⁰ reveals the Father (cf. Jn 1:14, 18). What human reason seeks “without knowing it” (cf. Acts 17:23) can be found only through Christ: what is revealed in him is “the full truth” (cf. Jn 1:14-16) of everything which was created in him and through him and which therefore in him finds its fulfilment (cf. Col 1:17).

35. On the basis of these broad considerations, we must now explore more directly the relationship between revealed truth and philosophy. This relationship imposes a twofold consideration, since the truth conferred by Revelation is a truth to be understood in the light of reason. It is this duality alone which allows us to specify correctly the relationship between revealed truth and philosophical learning. First, then, let us consider the links between faith and philosophy in the course of history. From this, certain principles will emerge as useful reference-points in the attempt to establish the correct link between the two orders of knowledge.