It is a commonplace in liberal biblical scholarship to claim a contradiction between 1 Samuel 16:14-23 and 1 Samuel 17:55-58. The nature of the alleged contradiction lies in what Saul knew and when. In 16:19, Saul sends a messenger to Jesse, after he has been told about Jesse’s son by the young man of verse 18. The messenger tells Jesse to send David (“your son”) to Saul for purposes of musical distraction. In chapter 16, therefore, Saul knows whose son David is. In the very next chapter, however, Saul seems not to know this information. In 17:55 and following, Saul asks Abner about David’s parentage (Abner doesn’t know). Saul then finds out from David himself that David is the son of Jesse. So, which is it? Did Saul not find out in 16 about David’s father? Or are there other possibilities?
The first thing that must be said is that the author (or, to go momentarily on the liberal turf, the redactor) most likely already knew about this issue. Ancient authors weren’t quite as stupid as some modern scholars tend to think they were! How do we know? In the text of verse 23 lies what I believe to be the hint that points to the solution. The first two words of the verse are well translated, “Now, whenever…” The verse then describes a state of affairs that appears to have lasted a relatively long while before the events of 17. This points to the answer: Saul simply forgot whose son David was. The length of time combined with the stress of the events of 17 could easily explain Saul’s forgetfulness on this point.
To my mind, this explanation works better than some of the alternatives. Some believe that chapter 16 is about David’s identity, whereas 17:55ff. is about Jesse’s. This explanation does not take 16:18-19 adequately into account, where twice it is stated that Saul knew Jesse to be the father of David.
Another unlikely interpretation is that 16:14-23 is out of chronological order, and belongs in between 18:9 and 18:10. This would make the Goliath story the very first time Saul met David. Now, this would solve the issue. The Bible does not always record things in chronological order. What makes this solution unlikely is not the supposedly “unbiblical” nature of the solution, but rather the unlikelihood of the passage getting put intentionally out of place. If 16:14-23 was originally between 18:9 and 18:10, why would anyone move it?
Gleason Archer, in his Encyclopedia of Bible Difficulties (175), argues that Saul’s concern in 17:55ff. was in building up his own personal bodyguard, and that Jesse’s identity was important because Saul viewed David as a “lead to obtaining more soldiers like him.” This is possible, and would be an additional element consistent with the idea of forgetfulness.
Robert Bergen adds two more aspectual possibilities in his commentary on Samuel (199). The issue of who gets the tax forgiveness could be another reason why Saul asks about David’s parentage. In addition, Bergen argues that the Spirit having left Saul means that Saul “was intellectually incompetent.” I might amend the latter to say that Saul was becoming incompetent, memory being not what it once was.
One last solution, possibly the least likely, is that of Robert Polzin. In his Samuel and the Deuteronomist: A Literary Study of the Deuteronomic History, Part Two: 1 Samuel (171-6), he argues that Saul’s question is 17:55 is actually a demand for David’s allegiance, not a question about identity. Again, this would solve the issue. However, it is difficult to see why we should interpret the text that way. Are there other instances in ancient literature where asking about the identity of a person’s father is equal to a demand for allegiance? This seems highly unlikely to me. The other solutions are better.