III AUGUSTINE’S DOCTRINE OF KNOWLEDGE AND AUTHORITY AND AUTHORITY 1 FIRST ARTICLE AUGUSTINE marks almost as great an epoch in the history of philosophy as in the history of theology. It was with him that the immediate assurance of consciousness first took its place as the source and warrant of truth. No doubt there had been a long preparation for the revolution which was wrought by his announcement of “the principle of the absolute and immediate certainty of consciousness,” as Windelband calls it, and his establishment of it in ” the controlling central position of philosophic thought.” But the whole preceding development will not account for the act of genius by which he actually shifted the basis of philosophy, and in so doing became ” the true teacher of the middle ages,” no doubt, but above and beyond that “one of the founders of modern thought.” 2 He may himself be said to have come out of Plato, or Plotinus; but in even a truer sense out of him came Descartes and his successors.3 When he urged men to cease seeking truth without them, and to turn within, since the home of truth is inside of man, he already placed them upon the firm footing which Descartes sought with his cogito ergo sum.4 If Augustine can be said to have had a philosophical master before he fell under the influence of the Neo-Platonists, that master must be discerned in Cicero. And from Cicero he derived rather a burning zeal in the pursuit of truth than a definite body of philosophical tenets or even a philosophical point of view. It is a mistake to think of him as ever surrendering himself to the skepticism of the New Academy. He does, indeed, tell us that, in his disillusionment with Manichaeism and his increasing despair of attaining the truth, the notion sprang up within him that the so-called Academics might after all prove the best philosophers, contending as they did that everything hangs in doubt and truth cannot be comprehended by men. 5 It is not strange that at such moments his thoughts surged in great waves towards their teachings.6 But he tells us also that he could not commit himself to them; not only because he was repelled by their heathenism,7 but also because he was shocked by their skepticism.8 His difficulty at the time lay, in fact, in another quarter. He found no obstacle in the attainment of certitude: but nothing but apodeictic certitude satisfied him. He entertained no doubt, for example, that seven and three make ten; what he demanded was the same kind and degree of certainty he had here, for everything else. In other words, he would not commit himself to any truth for which he did not have ready at hand complete demonstration.
Augustine’s point of departure was therefore the precise contradictory of that of the Academics. They asserted that we can never get beyond suspense because we lack all criterion of truth. The best we can do is to say that this or that looks like truth; that it is verisimile or probabile: we can never affirm that it is truth, verum; though, of course, we can as little affirm that it is not truth. Lacking all signum; we are left in utter and hopeless uncertainty. Augustine, on the contrary, in the apodeictic certainty of, say, mathematical formulas, was in possession of a sure criterion on the basis of which he could confidently assert truth. His difficulty was that he wished to apply this signum mechanically to every sphere of truth alike, and could content himself with no other kind of certitude. He was tempted to declare that nothing resting on less cogent grounds is known, or can be known, at all. What he needed yet was to learn that so far from the possession of apodeictic certitude for some things throwing into the s4adow of doubt all for which it cannot be adduced, it provides a basis for valid assurance with respect to them, too. On the basis of this signum we may obtain in every sphere at least the verisimile, the probabile - a sufficient approach to truth to serve all practical purposes; or rather truth itself though not truth in its purity, free from all admixture of error. In other words, in every department of investigation there is attainable real and clear, if somewhat roughly measured, knowledge. What we currently call a yard of muslin, for example, though shown by the application of a micrometer not to be ari exact yard, is yet by the self-same test just as truly shown to be a yard for all the practical ends for which muslin is used. The possession of a criterion gives validity to the verisimile; for who can declare that anything is like the truth unless he has the truth itself in mind with which to compare it and by which to judge it?
It was by a line of reasoning something like this that Augustine overthrew the Academics when, in his retirement at Cassiciacum, in the interval between his conversion and his baptism, he undertook to lay the foundations of a positive Christian philosophy. It is absurd to talk of a verisimile, he urged, unless the standard, the verum, is in our possession. And not only is this standard, this verum, certainly in the possession of every man and instinctively employed by him; but no one can by any means rid himself of it. Do what we will, we cannot help knowing that the world is either one or not one; 9 that three times three are nine; 10 and the like; that is to say the principles which underlie, say for example, logic and mathematics. And in knowing these things, we know them not only to be true, but to be eternally and immutably true, quite independently of our thinking minds - so that they would be equally true if no human minds had ever existed, and would remain true though the whole human race should perish.11 With this indefectible certainty of necessary truth the mind unavoidably knows, therefore, the laws of the true, the beautiful and the good,12 according to which, as its criterion, it judges all of the true, beautiful, and good which is brought into observation in the experience of life. Nor can doubt be thrown upon these things by calling in question the reality of the very mind itself by which they are known, and therefore the validity of its convictions. Rather, the reality of the mind is given in the very act of knowledge: for what is not cannot act. Say even that this act is an act of doubt. If the mind did not exist, it could not even doubt.13 The act of doubt itself becomes, thus, the credential of certitude. It is impossible even to doubt unless we are, and remember, and understand, and will, and think, and know, and judge: so that he that doubts must not and cannot doubt of these things, seeing that even if he doubts he does them.14 Even he who says, “I do not know,” thereby evinces not only that he exists and that he knows that he exists, but also that he knows what knowing is and that he knows that he knows it.15 It is impossible to be ignorant that we are; and as this is certain, many other things are certain along with it, and the confident denial of this is only another way of demonstrating it.