The most common answer is that wearing the hair up avoids other problems. A pastor's wife said that her hair would look good down only if it was curled. Since she felt it was wrong to curl her hair, she wore it up. A Sunday School teacher said that women who wear their hair down "can't keep the scissors out of it." A relative said that girls who are serious about doing well spiritually tend to put their hair up. All of that is well and good, but then our stand is a recommendation, not a Biblical command. (It would also mean that wearing the hair down occasionally would not be wrong.)
I've tried over the years to formulate a clear Biblical basis for our standard. Here is my best attempt. What do you think? Please comment.
I Corinthians 11: 1-16
The Covering
In I Corinthians 11, Paul addresses two main issues: why women should wear a covering(purpose) and what the covering should be (description).
The first is relatively clear. Paul states in verse 3 that there is an order of authority from God the Father to Jesus to the man (husband) to the woman (wife). He focuses in this passage on the latter two. He tells us that the man is head of the woman because she is his glory (vs 7), because Eve was made from Adam (vs 8), and because Eve was made for Adam (vs 9). However he balances the order of authority by noting that men and women are mutually dependent (vs 11), that all men are born from women (vs 12), and that all are equal in the eyes of God (vs 13). He then connects wearing a covering to the issue of authority. A man should not wear a covering while praying because doing so would dishonor his head (Jesus) since he is the head of the home (vs 4). A woman should wear a covering while praying to show honor to her head, her husband (vs 5). In addition, verse 10 says that her covering is a symbol of her submission to authority.
But what is the covering? Verse 15 makes it clear that the woman's hair is her covering. It says that her hair is given her "for" (in the Greek "Anti") or "in place of' a covering. But in what way is the hair a covering? It is not simply having hair, since that would make the whole discussion redundant. It is not simply having long hair, because Paul says that nature itself teaches women to have long hair, so again the discussion would be redundant. There are two clues to the answer. First, Paul discusses four types of hair in verse 6; shaved, shorn, uncovered, and covered. Since shorn hair would be cut hair, the uncovered hair must be uncut. Thus simply having uncut hair is as shameful as having a shaved hair or cut hair. Something must be done to the uncut hair so that it serves as a covering. The second clue is in verse 10. THere Paul says that the woman should have "power on her head" - in other words, the woman should have the symbol of authority (her covering which is her hair) on her head. This can't refer to the hair simply starting at the head and hanging down the back, since that is naturally what happens and Paul wouldn't have needed to clarify it. It seems to mean that a woman should wear her long, uncut hair upon her head.