Chapter II: Premises must precede such an enquiry. I lay them down as follows

(1) The refutation of any argument against the Faith is not a demonstration of the truth of the Faith. It is the removal only of an obstacle to the Faith. For the Faith is not arrived at by demonstration, but by demonstration it is shown to be at least tenable. The Faith is not a conclusion which all can reach by the formal action of reason, but a revelation to be defended by reason. The Faith is not a theory, but a thing. It is rational, but not deductively arrived at. There is no process whereby all mankind can be convinced of it as of an abstract proposition. But there is a process whereby all mankind can be convinced that each particular proposition against it has failed.

This principle in what is called “Apologetics” (that is, writings in defence of Catholic truth) is so generally neglected that it is of the first importance to make it quite clear at the opening of any discussion upon revealed religion.

A man who can see colours will never be able to prove colour to a colour-blind man. He can show that the colour-blind man’s arguments--e.g., that colours do not exist because if they did they would affect surface--are false. If he proceeds to establish the presence of colours positively, he must do so by analogy, by convergent evidence, by the manifest action of others, by the proved nature of other senses than that of sight. He can only _prove_ (in the strict deductive sense of the word “prove”) that the sense of colour is rational, acceptable without violence to the human mind; but that it is present he must establish by other methods.

Nearly all our modern debates in this matter are confused by the fact that one of the parties misconceives the nature of these debates. The opponent of Catholicism thinks that its apologist is, in arguing, trying to prove Catholic truth as one proves a case for a positive verdict. He is not. He is rebutting the supposed value of opposing evidence; he is pleading for a negative verdict; for acquittal of the charge “irrational.” When he comes to establishing the Faith positively, he does not do so by following one line of deductive reason, but by a mass of converging considerations.

History cannot be said to prove the Faith, save in the very extended use of the word “prove” to mean a general process of increasing conviction from the examination of what is revealed of the Church’s action on the world, of men’s attitude towards it, of the moral and intellectual activities of acceptors and rejectors compared. But it can be _proved_ that an increasing knowledge of History does not shake the Church’s claim to Divine Authority: while, on the contrary, a lesser knowledge is almost invariably more hostile to that authority than a greater.

(2) I have used the term “reason,” and this leads me to my second premise: The human reason is absolute in its own sphere.

That elementary truth is often denied to-day (though the minds which deny it can only use reason to arrive at this very conclusion!), but it is fundamental and I must postulate it as a necessary prelude to any discussion. For to argue with men who deny the basis of all argument is futile; it is like pleading in a court where the judge is a corpse and the jury a set of waxworks.

A man says, “The river Ohio flows eastwards.” I show by the compass, the map, and the sun, or in any other rational way you like that it flows westward. If he then answer me, “Oh! that is formal logic--I have no use for it! Westward and eastward are but apparent contradictories. They can be resolved into a higher unity. And, after all, what is ‘flowing’? And here is a bend of the river which does flow eastward for a mile or two. And a statement may well be true in a higher sense than the geographical one. And anyhow, the modern mind is no longer bound by the mediaeval fetters of dialectic”--if he replies with this sort of rigmarole, I must leave him to it. I am writing not for modernists--that is, not for people who think that a proposition can be both true and untrue at the same time--but for men of sane tradition who admit logic as a court of final appeal in things of the mind. For we Catholics regard reason as supreme in its own sphere and will admit nothing contrary to reason.

(3) Lastly, I must premise that we are discussing things as they are: the real Catholic Church; and are excluding from the discussion what is not germane to it. We are discussing the claim of the Catholic Church to authority, the claims of its accredited organs to express divine truth--not what some opponent may in ignorance regard as an accredited organ of the Catholic Church, when it is nothing of the kind, nor a supposed doctrine of the Church which the Church has never taught. Conversely, I do not admit as rebutting evidence such phrases as “all the best authorities” or “all the latest authorities”--they are worthless as evidence. I examine the grounds on which the affirmations are made, not the mere affirmation unsupported by anything but fashion. (Thus, if an opponent advance, “Marcus, a priest, said the earth was flat: it is proved round; therefore the Catholic Church was wrong,” it is replied that Marcus, a priest, is not the Catholic Church. Or if it be said, “The Catholic Church teaches that mankind is but six thousand years old,” it is answered, “Many heretical sects have taught this but the Catholic Church has never taught it.” Or if it be said, “The Catholic Church affirms the witness of the fourth Gospel but all reasoning men admit that it is spurious,” it is replied, “All reasoning men do not admit that it is spurious: that is but the affirmation of a fashionable school.”)