I was recently reading the latest edition of Halachically Speaking. It says:
A woman who is a widow r”l or divorcee still has an obligation to cover her hair.
But why is this so? Why should they be any different than unmarried women?
Presumably standard practice is that once a woman begins treating her hair as erva, she should continue doing so. (I believe I've heard this from Rabbis Broyde or Willig.)
Rabbi Moshe Feinstein does write that hair-covering while married is dat moshe, but hair-covering afterwards is dat yehudit. There is a great deal of discussion over what those terms mean, but most straightforward is the argument of Rabbi Yehuda Henkin, Rabbi Michael Broyde, and others that the former is completely objective, but the latter may have some cultural dependence.
(By the way, why do unmarried women not have to cover their hair? It appears their definition of erva is culturally subjective, hence not today.)
The obligation of hair-covering post-marriage is less than during marriage; thus (as indicated by rony), in one responsum Rabbi Moshe Feinstein allowed a young widow to uncover her hair as that was needed for her employment in an office (which sounds a bit like the Mad Men era, but I digress). In another responsum -- EH4:32.4 --, he allows a young divorcee to uncover her hair to increase the likelihood of meeting an eligible fellow. There are actually two reasons why this is helpful:
This is a very (extremely?) delicate subject. We must first understand what stands behind it and this forum may not be the best place to discuss it. The idea of "tzniut" is very deep and comes to help us build a meaningful and lasting married relationship. The chinuch (training? education?) starts at a very young age much before the boy/girl gets to the age of marrying. There are different customs depending on the congregations. I am happy that I don't have to be a posek in this subject! The source to cover the hair for married window is deHoraitah (Shulchan Haruch Even Haezer 21:2) and according to the commentators it includes even divorced and widows. Harav Feinshtein was asked on the subject (Igrot Moshe, Even Haezer 1:57) regarding if the widow or the divorced may loose her place of work if she comes with her hair covered. He said that in the case of need she can go with her hair uncovered. What is "case of need"? What about a situation of a young widow that hopes to re-marry and feels that is she goes with her covered it will decrease her chances?
While this question already has an accepted answer, I feel there is some information missing from it, hence my post.
First of all, the question assumes that hair covering should only apply to a woman who is married. This assumption is warranted, as the gemarra in Kesubos 72a teaches
ראשה פרוע דאורייתא היא דכתיב (במדבר ה, יח) ופרע את ראש האשה ותנא דבי רבי ישמעאל אזהרה לבנות ישראל שלא יצאו בפרוע ראש
A woman with an uncovered head [transgresses] a biblical injunction, as it is written: "And he shall uncover the head of the woman", and a Tannah from the Academy of Rabbi Yishmael taught: This is a prohibition to the daughters of Israel that they should not go out with an uncovered head
The verse used to derive this prohibition is from the Sotah ritual, which involves a suspected adulteress (see the two explanations of Rashi there for how the gemarra derives this). Only a married woman could be a Sotah, therefore it would make sense that only a married woman should have her hair uncovered.
Based on the above, Rav Moshe Feinstein in Igros Moshe, Even HaEzer Volume 1 Simman 57 writes the following:
שגם אלמנה אסורה ללכת פרועת ראש הוא רק מצד דת יהודית דמדאורייתא הא רק בא"א נאמר
Even [though] a widow is prohibited to have an uncovered head, that is just from the law of Das Yehudis, since from on a Biblical level this injunction was only stated regarding a married woman.
He says it's only Das Yehudis, which is a prohibition on a Rabbinic level. He wants to use this, using one of the explanations in Rashi to allow a widow to have an uncovered head if there is a great financial loss involved. He even adds at the end:
ויש גם לומר שאולי דת יהודית הוא רק מדיני מנהג שאין לאסור באופן שלא מצינו שנהגו ובמקום הפסד הא לא מצינו שנהגו
You can even say that perhaps this Das Yehudis [prohibition] is only at the level of a minhag (custom), which shouldn't prohibit in a situation where we haven't seen people follow it. [Therefore] in a case of loss, we haven't seen people follow it (to cover their head).
Rav Yitzchok Berkowitz (in a shiur I heard) is astounded at Rav Moshe for failing to mention the opinions of the Bach (ד"ה לא ילכו) and Vilna Gaon (Seif Kattan 11) to Even HaEzer Simman 21 that a widow/divorced woman1 has to cover her hair at a biblical level. They derive it from the gemarra's choice of language אסור לבנות ישראל, the daughters of Israel, instead of saying אסור לאשת איש, a married woman.
Now, Rav Moshe does have a point. Sotah is only talking about a married woman. Therefore Rav Berkowitz suggests that the Bach and Vilna Gaon understand the drash of Chazal to either (a) be a gezeiras hakasuv (decree of the writ), or (b) a binyan av. He feels a gezeiras hakasuv is a bigger chiddush (novelty), so therefore he takes the approach of a binyan av. How can we understand this binyan av?
He says that the Torah obligates a woman who has reached a certain social status to wear something that shows that status, and the Torah objectively chose a head covering. A woman who is married is not the same as a single woman. Once a woman is no longer married, she doesn't revert to being a young single girl again. She's still the wise balabusta everyone seeks advice from. Therefore, even a widow/divorced woman should cover her hair.
1. Note the Tur and SA specifically say a single or married girl has to cover their hair. While a widow/divorced woman is in fact now single, the term single doesn't exclusively mean someone previously married. The Bach quotes the Mordechai that hair we're used to seeing doesn't need to be covered, and assumes that's talking about a virgin. Therefore it would sound like the Bach is talking about anyone who isn't a virgin, whether they were married or not, has to cover their hair based on this drash. However, Rav Berkowitz understands that the Bach and Vilna Gaon are only talking about a woman who was previously married.