Nicene and Post-Nicene Fathers, Vol. II:
On Christian Doctrine: Chapter 34

Chapter 34.—It is One Thing to Know the Laws of Inference, Another to Know the Truth of Opinions.

52.  Therefore it is one thing to know the laws of inference, and another to know the truth of opinions.  In the former case we learn what is consequent, what is inconsequent, and what is incompatible.  An example of a consequent is, “If he is an orator, he is a man;” of an inconsequent, “If he is a man, he is an orator;” of an incompatible, “If he is a man, he is a quadruped.”  In these instances we judge of the connection.  In regard to the truth of opinions, however, we must consider propositions as they stand by themselves, and not in their connection with one another; but when propositions that we are not sure about are joined by a valid inference to propositions that are true and certain, they themselves, too, necessarily become certain.  Now some, when they have ascertained the validity of the inference, plume themselves as if this involved also the truth of the propositions.  Many, again, who hold the true opinions have an unfounded contempt for themselves, because they are ignorant of the laws of inference; whereas the man who knows that there is a resurrection of the dead is assuredly better than the man who only knows that it follows that if there is no resurrection of the dead, then is Christ not risen.