The Augustinian hypothesis is one of the proposed solutions to the Synoptic problem. Its proponents believe that the Gospel of Matthew, was written first. The Gospel of Mark was written second, based on material found in the Gospel of Matthew, and amplifying some of it with more detail. The Gospel of Luke was written third using information found in the Gospel of Mark and the Gospel of Matthew. Many advocates of the hypothesis, hold that the Gospel of Matthew was written by Matthew, the Gospel of Luke was written by Luke, and that the Gospel of Mark was written by Mark.
Statement of the Augustinian Hypothesis
Saint Augustine wrote: "Now, those four evangelists whose names have gained the most remarkable circulation over the whole world, and whose number has been fixed as four ... are believed to have written in the order which follows: first Matthew, then Mark, thirdly Luke, lastly John ... Of these four, it is true, only Matthew is reckoned to have written in the Hebrew language; the others in Greek... For Matthew is understood to have taken it in hand to construct the record of the incarnation of the Lord according to the royal lineage, and to give an account of most part of His deeds and words as they stood in relation to this present life of men. Mark follows him closely, and looks like his attendant and epitomizer. For in his narrative he gives nothing in concert with John apart from the others: by himself separately, he has little to record; in conjunction with Luke, as distinguished from the rest, he has still less; but in concord with Matthew, he has a very large number of passages. Much, too, he narrates in words almost numerically and identically the same as those used by Matthew, where the agreement is either with that evangelist alone, or with him in connection with the rest. On the other hand, Luke appears to have occupied himself rather with the priestly lineage and character of the Lord" The Four Evangelists thus wrote in the traditional order - from Saints Matthew through Mark and Luke to Saint John finally - but each with their own unique emphasis and special focus.
Evidence for the Augustinian Hypothesis
External evidence is clearly demonstrative that St. Matthew the Apostle himself wrote the Gospel of Matthew, wrote first, and wrote well before the destruction of the Temple in Jerusalem in A.D. 70. This is attested by Bishop Saint Papias who knew St. John the Apostle, Tertullian in Africa, Saint Irenaeus, who was Bishop of Lyons in Europe but well acquainted with the Tradition of the East, having spent a significant time in Asia, and several other witnesses; and thus we have the unanimous witness of three whole continents and virtually the entire early Christian world that Saint Matthew the Apostle is the first of the Evangelists and wrote his Gospel well before 70 A.D.
St. Irenaeus records: "Matthew also issued a written Gospel among the Hebrews in their own dialect, while Peter and Paul were preaching at Rome, and laying the foundations of the Church. After their departure, Mark, the disciple and interpreter of Peter, did also hand down to us in writing what had been preached by Peter. Luke also, the companion of Paul, recorded in a book the Gospel preached by him. Afterwards, John, the disciple of the Lord, who also had leaned upon His breast, did himself publish a Gospel during his residence at Ephesus in Asia."
Saint Jerome knew where the original Gospel of Saint Matthew, in the library of Caesarea, in the Hebrew dialect, was kept in his day. “The Hebrew itself has been preserved until the present day in the library at Cæsarea which Pamphilus so diligently gathered. I have also had the opportunity of having the volume described to me by the Nazarenes of Berœa, a city of Syria, who use it”. .
The Time of St. Peter's preaching in Rome
The next step in historical investigation is to ascertain the time of St. Peter preaching in Rome. St. Jerome writes: "Simon Peter the son of John, from the village of Bethsaida in the province of Galilee, brother of Andrew the apostle, and himself chief of the apostles, after having been bishop of the church of Antioch and having preached to the Dispersion — the believers in circumcision, in Pontus, Galatia, Cappadocia, Asia and Bithynia — pushed on to Rome in the second year of Claudius to overthrow Simon Magus, and held the sacerdotal chair there for twenty-five years until the last, that is the fourteenth, year of Nero. At his hands he received the crown of martyrdom being nailed to the cross with his head towards the ground and his feet raised on high, asserting that he was unworthy to be crucified in the same manner as his Lord. He wrote two epistles which are called Catholic, the second of which, on account of its difference from the first in style, is considered by many not to be by him. Then too the Gospel according to Mark, who was his disciple and interpreter, is ascribed to him."
Secular history informs us the second year of Claudius is 42 A.D. and the 14th year of Nero is 67 A.D. The time of St. Peter’s preaching being known, the dates for St. Matthew's Gospel being published can be calculated.
Major: St. Matthew the Apostle wrote when St. Peter (and St. Paul) were preaching in Rome.
Minor: But St. Peter began to preach in Rome in 42 A.D. and St. Peter was martyred by 67 A.D.
Conclusion: Therefore, St. Matthew wrote the First Gospel between the years 42-67 A.D.
Saint Matthew wrote before Saint Luke
The Gospel of Saint Luke can be dated in two ways (1) The Gospel of St. Luke clearly pre-dates the Acts of the Apostles (as the preface to Acts shows, it is the second letter to Theophilus) and (2) The Gospel of St. Luke was already widely distributed in the Churches when 2 Corinthians was written.
St. Luke abruptly ends the Book of Acts during St. Paul's imprisonment, showing St. Paul was alive when Acts was written. But St. Paul died in 67 A.D. by martyrdom together with St. Peter as seen above. Thus, Acts pre-dates A.D. 67. It was likely written during St. Paul's imprisonment around 61 A.D.
Further, the secularist Encyclopedia Brittanica admits admits: “The Second Letter of Paul to the Corinthians (II Corinthians in the New Testament) was written from Macedonia in about 55 CE[sic]”. Thus, since the Epistle of II Corinthians states St. Paul is sending “the brother, whose praise is in the gospel through all the churches" (2 Cor 8:18), clearly St. Luke, it follows that the Gospel was already written by 55 A.D.
It can also well be concluded, from the text, that the Gospel of St. Luke was not only written but even widely distributed already by this Epistle date.
Major: St. Matthew the Apostle wrote before St. Luke the Evangelist, the disciple of St. Paul.
Minor: But St. Luke wrote Acts before 61 A.D. and the Gospel of St. Luke before 55 A.D.
Conclusion: Therefore, St. Matthew wrote well before 61 A.D. and even 55 A.D. as well.
Finally, a recent discovery, of 7Q5 papyrus,  an early papyrus of St. Mark’s Gospel, shows:
Major: St. Mark the Evangelist, disciple and secretary of St. Peter the Apostle, on summarizing his preaching, manifestly wrote before 50 A.D., as we have 7Q5 papyrus that shows us his Gospel was written before that time.
Minor: But St. Matthew the Apostle, as the Fathers unanimously hand down the historical Tradition, wrote before St. Mark.
Conclusion: Therefore, likewise, we can conclude as a certain historical Truth, St. Matthew wrote well before even 50 A.D.
Summarized Dates of the Synoptic Gospels
Gospel of St. Matthew: 42 A.D. (Most likely). Probable range: (42-45) A.D. [during St. Peter's preaching. Before St. Luke wrote Acts. Before St. Luke wrote the Gospel of Luke. Before St. Mark wrote the Gospel of Mark.]
Gospel of St. Mark: 45 A.D. (Most likely). Probable range: (44-48) A.D [St. Peter’s preaching in Rome. Before 50 A.D. based on 7Q5 Papyrus. And before St. Luke wrote his Gospel, therefore well before 55 A.D.]
Gospel of St. Luke: 48 A.D. (Most likely). Probable range (48-52) A.D. [with at least 3 years of sufficient time for distribution, so that what St. Paul says in 2 Cor 8:18 in 55 A.D. could have come about by then]
Since in the Council of Jerusalem, the Apostles began to lay greater emphasis on the preaching of the Gospel to the Gentiles also, it is likely St. Paul, the Apostle to the Gentiles, with the other Apostles, would have seen to it that this Gospel, written by his disciple, would be released then.
- (Harmony of the Gospels, Book I, Chapter 2). https://www.newadvent.org/fathers/1602102.htm
- (Adversus Haereses Book III, Chapter 1), https://www.newadvent.org/fathers/0103301.htm
- (De Viris Illustribus, #3, on Saint Matthew), https://www.newadvent.org/fathers/2708.htm
- (De Viris Illustribus, #1, on Saint Peter). https://www.newadvent.org/fathers/2708.htm
- https://www.britannica.com/topic/The-Letter-of-Paul-to-the-Corinthians Encyclopedia Brittanica
- https://bible.org/article/7q5-earliest-nt-papyrus Earliest NT Papyrus.