In a popular commentary on the Bible you will find a discussion on the date at which the Fourth Gospel was written. The author says it must have been written after the execution of St. Peter, because, in the Fourth Gospel, Christ is represented as predicting the execution of St. Peter. ‘A book’, thinks the author, ‘cannot be written before events which it refers to’. Of course, it cannot—unless real predictions ever occur. If they do, then this argument for the date is in ruins. And the author has not discussed at all whether real predictions are possible. He takes it for granted (perhaps unconsciously) that they are not. Perhaps he is right: but if he is: but if he is, he has not discovered this principle by historical inquiry. He has brought his disbelief in predictions to his historical work, so to speak, ready made. Unless he had done so his historical conclusion about the date of the Fourth Gospel could not have been reached at all. His work is therefore quite useless to a person who wants to know whether predictions occur. The author gets to work only after he has already answered that question in the negative, and on the grounds which he never communicates to us.
--C.S. Lewis,
Miracles
