I’ve been asked to explain headcoverings in Judaism. I’m going to do this in separate parts, because those for men and women have very different justifications and rules, even though we’ll find that they’re distantly related as far as reason goes.
I’m going to start with the more difficult, though generally less touchy, issue of the kippah. Now, this is clearly not a Biblical commandment and, contrary to common opinion, it doesn’t even fall under the umbrella of Rabbinic institution. This is simply a custom of Israel. The primary basis for the kippah in Jewish law is from Shulchan Aruch, Orach Chayim 2:6. A man should not walk more than four amot (about six feet) without his head covered. It is important to realise that Shulchan Aruch records what was current Jewish practice in the sixteenth century. It is not a record of traditions like the Mishnah. It is also not a direct commentary on the Bible or the Mishnah.
So if there is no commandment, how did we get this tradition? The generally accepted story is that it begins with the Biblical commandment that Priests should not uncover their heads when serving in the Temple (Lev. 21:10). From the priesthood there was a kind of trickle-down to any great men, as we see in the Talmud’s story of R. Nahman Ben Isaac (z”tzl). R. Nahman’s mother was told that her son would grow up to be a thief, so from an early age she always kept his head covered so that “the fear of heaven may be on you, and you may pray for mercy.” One day, while studying Torah, R. Nahman’s kippah blew off his head, and he immediately fell under temptation and went up and stole an apple from a stranger’s apple tree. Babylonian Talmud, Shabbat 156b
Be as skeptical as you like about the content of the story of R. Nahman, but it tells us both that by the time the Gemara was written (finished around 500 CE) it was not unusual for a sage to be wearing a kippah, and the purpose of wearing a kippah. Like R. Nahman’s mother said, the reason we cover our heads is so that the fear of heaven will be on us, and so that we may pray for mercy. The kippah, like the tzitzit, reminds us of God’s sovereignty over us and our duties to Him. To show submission, we ought to cover our heads whenever we pray, and we cover our heads all the time so that we can pray for mercy all the time.
Why should we accept this tradition? After all, it’s not in the Bible, or even the Mishnah, Talmud, or Tosefta. There is a story about a proselyte who comes to R. Hillel and asks him to teach him only the written Torah, without any traditions of Israel. R. Hillel agrees, and begins him with the Hebrew alphabet. The man goes home and memorizes the alphabet. Next day, he comes back and recites it for R. Hillel. The rabbi approves, and then tells him the alphabet backwards, and tells the man to learn it. The man is surprised and asks which way is correct. R. Hillel replies, you trusted me about the alphabet, so why don’t you trust me about the traditions? Babylonian Talmud, Shabbat 31a.
One more reason why we should keep this tradition, R. Yeshua tells us that the Scribes and Pharisees sit in Moses seat, and that we ought, therefore, to do as they tell us (Matt. 23:2-3). The rabbis are the spiritual descendants of the scribes and pharisees, and as such we still ought to follow their rulings. Besides, this is a good tradition. It shows our humility before God when we pray, and reminds us throughout our day that we are supposed to constantly be in a prayerful attitude.