When it is clear that even the prophets and apostles themselves were not complete strangers to error, what is so surprising, then, if among such manifold writings of the Holy Fathers some things seem to be handed down or written erroneously, for the reason given above? But just as these holy ‘defendants’ should not be charged with lying if at one time or another, not from duplicity but from ignorance, they make some statements other than what the real truth would have them think; so in the same way something that is said for love while giving some instruction should not be imputed to presumption or sin, since it is well known that all things are distinguished by God according to intention, just as it is written (Matthew 6:22), "If thy eye be sound, thy whole body will be full of light." Whence also this passage St. Augustine in his treatise on Church discipline: "Have love," he says, "and do what you will." And this on the Epistle of John (In Epist. Ioan. ad Parthos, tract. V, 7) "Those who have no love are not of God. Have whatever you wish, but if love is the only thing that you do not have, then nothing avails you. If you should have nothing else, but you do have love, then you will fulfill the Law." And further (tract. VII, 8), "Therefore a single brief precept is commanded of you: Love, and do what you will." And this from the first book of On Christian Doctrine (I, xxxvi, 40), "Whoever seems in his own opinion to understand the Holy Scriptures or any part of them, such that with this understanding he does not build up that twofold love of God and of his neighbor, then he does not yet understand. But if someone has derived from there an idea such that it is useful for building up love, then although he may not have said something that the author whom he is reading is proven to have meant in that spot, still, he is not dangerously deceived nor is he lying at all. For lying involves the intent of speaking false things." And in the Against Lying (Contra Mendacium, xii, 26): "Lying is a false meaning in what is said, combined with the intent of misleading." And in the Enchiridion, chapter 23 , "No one is rationally judged to be lying when they say something false that they believe is true, because, inasmuch as one believes it, one does not deceive but is oneself deceived. Likewise, someone who holds false opinions, carelessly accepted in place of true ones, ought to be accused not of lying but of sometime rashness. On the other hand, anyone lies who says a true thing, while believing that it is false. For insofar as his intent is concerned, because he does not say what he believes, to that extent he does not speak the truth, even if what he says may actually turn out to be true. Nor is someone free from lying, if they unwittingly speak the truth, but lie insofar as their knowledge and intent." And this (Enchiridion 22): "Everyone who lies speaks in contradiction to what he believes in his mind, with the intention of deceiving." And also, in Book Two of his commentary on the Gospels (Contra Mendacium x, 24): "That Jacob managed at his mother’s bidding to seem to deceive his father; if examined carefully, is not a lie but rather a mystery. For a truthful [i.e. allegorical] meaning can in no way rightly be called a lie." Indeed in this passage the spiritual teacher only accepts as a lie a transgression which God, who is the judge of hearts and passions, weighs according to the intent of the speaker rather than according to the quality of the speech, paying attention not so much to what is done as to the spirit in which it is done. According to this, anyone is guiltless insofar as they think sincerely and without falseness and do not speak deceitfully – just as it is written (Proverbs 10:9), "He that walketh sincerely, walketh confidently." Otherwise even the Apostle Paul might be accused of lying when he follows his own judgement rather than the truth of the matter as he writes to the Romans saying (Romans 15:28), "Therefore when I have completed this, and have delivered to them the proceeds, I will set out by way of you for Spain." Thus it is one thing to lie and another to be mistaken while speaking and to stray from the truth in one’s words due to error, not to malice.
If God on occasion does allow this to happen even to the holy ones themselves, as we have said, in those situations that would cause no damage to the faith, it does not happen unproductively to those by whom everything is undertaken for the good. Even the ecclesiastical teachers themselves, diligently attentive and believing some things in their works needed correction, grant to posterity the license to emend or not to follow them; if somehow these teachers were not able to retract or correct in their works. Whence even the teacher Augustine, cited above, in Book One of his Retractions (prologus 2): "It is written," he says, "you do not avoid sin by loquacity." And also "The apostle James says (James 1:19), ‘Let every man be swift to hear but slow to speak’.’" And " (James 3:2) ‘For in many things we all offend. If anyone does not offend in word, he is a perfect man.’ I do not claim this perfection for myself even now, when I am an old man – how much less when as a young man I began to write." And in the prologue to Book Three of the On the Trinity (proem 2): "Do not defer to my writings as if they were canonical scriptures, but whatever you would find in the canonical scriptures that you did not believe, believe steadfastly. But in my writings I do not want you to accept with assurance something that you had not been taking as certain unless you now understand it as certain." And in the letters to Vincentus Victor, Book Two (De Anime et eius Origine iv, 1): "I cannot, nor should I, deny that just as I might be blamed for many things in my conduct by fair judgement without rashness, so I might be blamed for many things in my writings." And again in his letter to Vincent (Epist. 95, x, 35), "Do not desire, brother, to collect calumnies against such clear divine witnesses -– either from our writings, or from Hilary, or from Cyprian and Agrippinus, because this type of writing should be distinguished from the authority of the canon. For they are not to be read as if it were not permissible to disagree with the testimony presented in them, if in some place they should claim to know otherwise than the truth demands." And again to Fortunatianus (Epist. 148, iv, 15): "Nor ought we to regard the arguments of anyone, no matter how Catholic and well-regarded, in the way we regard the canonical scriptures, that is (with all due respect to these men) as if we were not permitted to refute or reject something that we find in their writings where their opinions differ from the established truth. I wish my readers to hold the same attitude toward my writings as I hold toward the writings of others." And again in the Response to Faustus (Contra Faustum, Book 1, Chapter xi): "We are far from saying that Paul sometimes erred and changed his opinion as he advanced. For one could say that the books we have written, not with the authority of commanding but in the exercise of utility, are not comparable to the [canonical] books." And again (Contra Faustum, XI, v): "For we are the ones of whom the Apostle said: ‘and in any point you are minded otherwise, this also God will reveal to you’ -- this type of writing of letters should be read not with a compulsion to believe but with the freedom to evaluate. However, so that the room for this freedom is not excluded, and that very healthy task of treating difficult questions and translating their language and style is not denied to later authors, the excellence of the canonical authority of the Old and New Testaments has been distinguished from that of the works of later authors. If there should be something in the Old or New Testament that seems as if it were absurd, you may not say that the author of this work did not possess the truth, but that the manuscript is corrupt, or the translator has made a mistake, or that you do not understand. But in works of later witness, contained in innumerable volumes, if perhaps some things are thought to deviate from the truth because they are not understood as they have been expressed, in these works the reader or listener has the freedom of judgement to approve what seems good or disapprove of what offends, and therefore when it comes to things of this type, unless they are supported either by sure reasoning or canonical authority, so that what is either argued or narrated there may be shown either to be entirely so or to be potentially so, if it does not seem good to someone or they do not wish to believe it, they are not reproached."
(292-304) And thus he calls the canonical Scriptures of the Old and New Testaments documents about which it is heretical to say that something in them contradicts the truth. Indeed, concerning these Scriptures he writes thus in his fourth letter to Jerome (Epist. 40, iii, 3): "In the explanation of the Apostle Paul’s letter to the Galatians I find something that pains me deeply. For if even white lies were permitted to the Holy Scriptures, what authority would they retain? How, I pray, could this view be set forth concerning the same Scriptures by whose weight the contentious depravity of falsehood is crushed?" And again, to the same man also about Holy Scripture (Epist. 28, iii, 3): "It seems to me a most dangerous thing to allow that anything in the sacred books may be a lie, that is, that those men who preserved and wrote the Scriptures for us should have lied about anything in their books. For if a single white lie is admitted anywhere in so lofty an authority, then no particle of these books will remain which will not be explained as the idea or practice of the author’s mind, using this most dangerous example whenever anyone finds something difficult to practice or hard to believe."
St. Jerome, also, when he preferred some ecclesiastical doctors to the rest, thus counseled us that they should be read in order to judge among them rather than merely accepting them. Whence this advice of his in his letter to Laeta concerning the education of her daughter (Epist. 107, 12): "The works of Cyprian she ought always to hold in hand; the works of Athanasius and the book of Hilary to tread with an unhindered foot; let her enjoy the treatises and talents of those in whose books the piety of faith does not waver. The others she ought to read so as to judge rather than to accept." So also in speaking on Psalm 86, as if clearly offering his authority on all these writers, Jerome says (Tractatus de Ps. 86): "‘the Lord will tell, in the writings of the leaders and the princes, those who were in her [i.e. Zion]’. He did not say ‘those who are in her’ but ‘those who have been in her’. ‘Of the peoples’ is not enough, but he also says ‘of the princes’ –- and of what princes? Of ‘those who have been’. Thus you may see how the sacred Scripture is filled with holy mysteries. We read the Apostle saying (2 Corinthians 13:3), ‘Do you seek a proof of the Christ who speaks in me?’ What Paul said, Christ said (‘For he who receives you, receives me’ – Matthew 10:40) in the Scripture of the princes and ‘in the Scripture of the peoples’, which is the Scripture for all people. You may see what he says: ‘those who have been’, not ‘ those who are’, so that with the exception of the apostles whatever else is said afterwards is separate, and does not possess authority afterward. Therefore, however holy someone may be who lived after the apostles, and however well-spoken, he does not possess authority." And the same author writing to Vigilantius (Epist. 129, 11): "Whoever reads works of many treatises ought to be like a trusted moneychanger so that he rejects any coin that is false and lacks the image of Caesar and is not marked by the public mint; but the coin showing the face of Christ in the clear light he stores up in the pouch of his heart. For what ought to be pondered is not the predecided opinion of the teachers, but the logic of the teaching, as it is written (1 Thess. 5:21), ‘Test all thing; hold fast that which is good.’" However, this is said in reference to the commentators, not in reference to the canonical Scriptures, in which one should have undoubting faith. Jerome also wrote to Paulinus concerning the holy teachers in the Good Man Concerning the Good Treasure of the Heart (Epist. 58, 1, 10): "I am silent concerning the rest, both the dead and those still living, over whom others after us may judge either way."
- Peter Abelard (1079-1142), Sic et Non, Prologue, lines 249-329 (copied with permission from the linked source)