Chizuk Emunah (Pt 2) Under the Microscope: Chapter 67

Acts 13:21, Paul says of the Israelites, "And afterwards they desired a king, and God gave unto them Saul, the son of Kish, a man of the tribe of Benjamin, by the space of forty years."
Paul erred in assigning to Saul such a protracted reign. Saul had governed only two years when his dereliction of the will of God, in his war against the Amalekites, threw him into disfavour, so that he forfeited his crown. Samuel was then immediately sent to anoint David, who was about twenty years old; when he [David] ascended the throne, he was but thirty years of age (see 2 Samuel 5:4); consequently Saul could not have governed Israel more than ten years. If we follow an hypothesis of Albo, the author of the book, entitled Sepher Ikkarim, Saul did not occupy the throne even so long a time; but certainly could not have remained king for forty years.

This is from Paul's speech to the people of Antioch.

“Men of Israel and you who fear God, listen. The God of this people Israel chose our fathers and made the people great during their stay in the land of Egypt, and with uplifted arm he led them out of it. And for about forty years he put up with them in the wilderness. And after destroying seven nations in the land of Canaan, he gave them their land as an inheritance. All this took about 450 years. And after that he gave them judges until Samuel the prophet. Then they asked for a king, and God gave them Saul the son of Kish, a man of the tribe of Benjamin, for forty years. And when he had removed him, he raised up David to be their king, of whom he testified and said, ‘I have found in David the son of Jesse a man after my heart, who will do all my will.’ Of this man's offspring God has brought to Israel a Savior, Jesus, as he promised. Before his coming, John had proclaimed a baptism of repentance to all the people of Israel. And as John was finishing his course, he said, ‘What do you suppose that I am? I am not he. No, but behold, after me one is coming, the sandals of whose feet I am not worthy to untie.’ (Acts 13:16-25)

 Again, this is from Acts, which is not written by Paul. A doctrine like inerrancy only requires that Luke had recorded Paul's words accurately. Still, Paul had a reputation as a great scholar of his age. Also note that Paul's speech was not to the Jews of Jerusalem but to the people of Antioch. In fact, Josephus sides with Paul on this matter. He writes:

To this his end did Saul come, according to the prophecy of Samuel, because he disobeyed the commands of God about the Amalekites, and on the account of his destroying the family of Ahimelech the high priest, with Ahimelech himself, and the city of the high priests. Now Saul, when he had reigned eighteen years while Samuel was alive, and after his death two [and twenty], ended his life in this manner. 

 Both are counting Saul's reign from the very beginning to the time he took his own life. By this calculation, Saul's reign did not end when David was anointed by Samuel. Indeed, David himself said that he would not touch the Lord's anointed, and this was after Saul had fallen out of favor with God.

1 Samuel 9 states that Saul was a young man when he was anointed king. Yet, 2 Samuel 2 states that the youngest of Saul's four sons, Ishbosheth, was forty years old when Saul was killed. Ishbosheth was so young that he was not even mentioned in 1 Samuel.

Now the sons of Saul were Jonathan, Ishvi, and Malchi-shua. And the names of his two daughters were these: the name of the firstborn was Merab, and the name of the younger Michal. And the name of Saul's wife was Ahinoam the daughter of Ahimaaz. And the name of the commander of his army was Abner the son of Ner, Saul's uncle. Kish was the father of Saul, and Ner the father of Abner was the son of Abiel. (1 Samuel 14:49-51)

If Saul's reign had been as short as Troki thinks, how is it that his fourth son was forty years old when he died? I think it is because Troki is using a different method of figuring out Saul's reign than Paul is doing

Finally, Masoretic Text of 1 Samuel 13:1 is almost certainly corrupted. The text literally reads "Saul was one year old when he began to reign; and he reigned two years over Israel." Other variants of the text have different numbers, and the footnote of the NRSV states that these numbers are not complete, and that something was dropped out. Emanuel Tov discusses this in Textual Criticism of the Hebrew Bible chapter 1.