Sources of Knowledge Discussion

THE APPEAL TO FAITH

Faith, as it is ordinarily understood, is “belief that does not rest on log- ical proof or material evidence.”21 To believe something on faith is to believe it in spite of, or even because of, the fact that we have insuffi- cient evidence for it. No one has expressed this cavalier attitude toward evidence better than Tertullian: “It is to be believed,” he said, “because it is absurd.”23 Saint Thomas Aquinas considered faith to be superior to opinion because it is free from doubt, but inferior to knowledge because it lacks rational justification. In the case of faith, the gap between belief and evidence is filled by an act of will—we choose to believe something even though that belief isn’t warranted by the evidence. Can such a belief be a source of knowledge? No, for we cannot make something true by believing it to be true. The fact that we believe something doesn’t justify our believing it. Faith, in the sense we are considering, is unquestioning, unjustified belief, and unjustified belief cannot constitute knowledge.

The problem with the appeal to faith is that it is unenlightening; it may tell us something about the person making the appeal, but it tells us nothing about the proposition in question. Suppose someone presses you about why you believe something and you say, “My belief is based on faith.” Does this answer help us evaluate the truth of your belief? No. To say that you believe something on faith is not to offer any justification for it; in fact, you are admitting that you have no justification. Since believing something on faith doesn’t help us determine the plausibility of a proposition, faith can’t be a source of knowledge.