I read a fascinating series of articles a few weeks ago in the Journal of the Evangelical Theological Society (JETS) about the Goliath "problem."
Clyde E. Billington, "Goliath and the Exodus Giants: How Tall Were They?" JETS v. 50, n. 4 (September 2007).
J. Daniel Hays, "The Height of Goliath: A Response to Clyde Billington," JETS v. 50, n. 4 (September 2007).
Skeptics say that the whole idea of a 9 foot, 9 inch ancient warrior is just plain silly. In fact, they claim it's direct evidence that the Bible is myth. So what do Christians do with this? Is Samuel's description of Goliath an exaggeration? Is the story itself a legend, an embellished true story?
Although the authors above answer this question differently, here is a general synopsis (as best I understand it) of their proposed solutions to the Goliath "problem":
1) The Bible actually says that Goliath was "6 cubits and a span" tall. The question is, how long is a "cubit" and a "span"? If you look in the footnotes of your Bible, it probably says that a cubit is 18 inches. But that is only a ballpark number. Technically speaking, a cubit is the length from the tip of your middle finger to your elbow. And a span is the distance from the tip of your longest finger to the base of your hand. Anyone who knows me knows that my husband's cubit and span are going to be significantly longer than mine. So, in order to try and standardize this measurement, the ancients developed the concept of a "royal cubit." But even that can vary from country to country.
Ok, back to Goliath. Goliath was "6 cubits and a span" tall, but according to which measurement? Well, since Samuel is the author of the book, maybe the cubit measurements were according to Samuel's cubit. Or, maybe they were according to David's cubit. Or maybe it was the royal cubit. The problem is, we don't know and just a couple inches of difference between each of these can add up quickly when dealing with a very long object.
2) Here is a second possibility. There is apparently, a scribal discrepancy between the Masoretic text and the Septuagint (Greek translation of the OT from the first century B.C.). Assuming the 18 inch cubit, the Septuagint rendering would make Goliath about 6 feet, 9 inches tall. That's about the size of a large NBA player. That's tall for the ancient world, but obviously within the realm of human genetic possibility.
3) A third option has been put forth by Hugh Ross that recognizes a 9 foot, 9 inch human is physically impossible (he explains the physics behind this assertion in his book, The Genesis Question). Ross points out that given the common OT view that Goliath was part of that race of large humans referred to in the Bible as the Nephilim or the Raphaelim. These "giants" were more common before Noah's flood, but a few somehow survived the flood (how that works I have no idea if Noah's flood wiped out all of humanity, but that's a topic for a different day) and then died out. It is commonly believed that the Nephilim identified in Genesis 6 were the product of intermarriage between human women and demons. So, given the possible demonic lineage of the Nephilim, they are were to defy the physical limitations of human genetics. That's probably a really bad synopsis of his view. Ross' argument is kind of complicated, but you can check it out in his book if you're interested in how he arrives at these conclusions.
In the midst of this important apologetic debate concerning the text's historical veracity, I think it's important not to lose the key theological point of the David and Goliath narrative. The author sets up a contrast between Saul, Goliath and David. Saul is described as being "an impressive young man without equal among the Israelites - a head taller than any of the others" (1 Sam. 9:2). Apparently, ancient Jews were on the shorter end of the height continuum. In fact, some skeletal studies have suggested that the average height of an ancient Jew was 5 feet, 5 inches to 5 feet, 7 inches. If Saul was a head taller than that, let's say he was somewhere between 5 feet, 9 inches and 6 feet tall. In contrast, David is probably still a teenager when he fights Goliath. It's possible that he hadn't even had his final growth spurt yet. He could have been somewhere between 5 feet and 5 feet, 3 inches tall.
Here is the irony. The largest, most impressive man in Israel is cowering in his tent because he doesn't want to go out and fight the largest enemy warrior. Along comes this little runt, David, who is willing to fight but isn't even big enough to wear the armor. The theological point here is for the reader to see that David's victory is all about God's power and that if God wants to save His people, He will do it in whatever unlikely way he chooses.
Now one question that might come to mind is, does this debate about Goliath's height even matter? I would say "yes" and here's why. The Bible consistently talks about descriptions of the past as real history, not legend. In fact, our very salvation actually rests on the veracity of certain historical events, such as the existence of Jesus, his death and resurrection. So, whatever resolution we come to about Goliath, I think it at least needs to be plausible. And I think that criteria is met in the options above.