I don’t think Josef Pieper wrote many big books—most of them are less than a hundred pages—but his writings are always heavy with meaning. In Belief and Understanding he fathoms the intricate question of faith with his usual concision and insight. The first thing Pieper does is what Socrates and Plato did when they wanted a philosophical definition. They looked at the meaning of a word and how it was used in everyday speech. It is clear that “belief” has different connotations. On the one hand, it can mean a mere guess or supposition, or maybe a qualified persuasion. But in religious terms it can only refer to “unreserved, unconditional assent.”
Belief deals with truths we do not fully understand. Where there is knowledge, Pieper points out, there is no need for belief. Thus when we say we believe something that we do not fully comprehend, like the Heisenberg principle of quantum mechanics, we are doing so on the authority of someone else. The point is that belief always points back to “one who knows.” In the case of the object of faith, which is God, only God himself fully comprehends the matter. This requires revelation. As Pieper explains, in Christianity “the content of the testimony [revelation] and the person of the witness [Jesus Christ] are identical.”
Finally, Pieper makes the point that belief does not imply an irrational “fideism.” Christianity is not a “blind faith” such as one finds in fanatical or fraudulent cults. “No one who believes must believe; belief is by its nature a free act.” Nor is everything within the ambit of religion a matter of “faith,” since some things can be fully understood by our unaided minds. “The premises of belief are not part of what the believer believes.” In other words, a certain credibility or probability must be established about the testimony of revelation as a precursor to belief. That is the role of apologetics. But faith itself is never reasoned. It is ultimately a leap taken on an established trust.
See related post on Pieper’s book The Four Cardinal Virtues.