[We share this response with the public hesitantly because it is far from clear that one who strives to be machmir[2] would be acting appropriately in changing his minhag. However, we do not want to ignore a topic that has already been discussed publicly.]
Two pertinent points are clear. First, the standard Talmudic instructions and practice were to light chanukiyot outside.[3] (One who lived in an attic put it in the window facing the street.[4]) Second, the longstanding custom in most Jewish communities has been to light inside.[5] How do we explain this change and decide how to act nowadays?
The gemara[6] says that in a time of danger, one should light on his table. The Itur[7] notes that once the practice to light inside developed, although based on the danger to light outside, it continued. Many poskim assert[8] that it is preferable to light outside, if it is possible to do so. (Rav Moshe Feinstein assumed that it was not possible in the United States in 1975, as was the case for his forebears in Europe.[9]) Rav Shternbach[10] strengthens the impact of the historical danger on the recommended practice. He suggests that when part of the populace is in a dangerous state of affairs, everyone should light inside because we do not want some people taking risks under the pressure to keep up with others who are able to light outside.
Other historical explanations are given. The Aruch HaShulchan[11] speculates that when Jews moved to windy and rainy places, glass cases were needed to protect the chanukiyot. Besides detracting from the intended publicity that one is lighting for a mitzva, these cases are not always feasible or affordable. Thus, the minhag arose to light indoors. If the climate were a factor to be taken into account, there would be logic to distinguish between one place and another, especially in Israel, considering that the relevant Talmudic text was written there or nearby.[12]
At this point in our inquiry, it would still seem that those who can succeed in lighting outside in glass cases should try to do so. However, other factors may “level the playing field.” At the time we light the chanukiya, it should have the potential to burn for a half hour.[13] If one opens the side of the case for the kindling and has to close it quickly before the wind blows out the candles, shouldn’t this be considered lighting in a place where the candles of the chanukiya, when they are being lit, would not last a half hour? Although there are reasonable answers to this question,[14] some poskim maintain that if one cannot light the candles in a manner in which the wind will be kept out from the outset, it is better to light inside.[15]
Another problem with lighting outside, especially for those who live in apartment buildings, is that it is not always clear where exactly one should light. Is it at the door between one’s apartment and the stairwell, at the entrance to the building, or at the edge of the sidewalk of the street, etc.? Is living on a higher floor considered like being in an attic?[16] Halachic research can provide sensible solutions for most circumstances. However, the fact that the minhag to light inside has been around for so long has made it more difficult to find sources providing answers to these questions. Therefore, this doubt as to precisely where to light outside may be yet another reason to continue lighting inside, as was almost universally done just a generation ago. Furthermore, if we light in the window facing the street,[17] the mitzva of publicizing the miracle is performed properly (on lower floors), and the chumra[18] of lighting outside may not turn out to be preferable at all.
Summarizing, there is an apparent advantage in lighting outside. However, since there are strong reasons not to require it, we would discourage lighting outside in places where it is not an accepted practice or where it could encourage vandalism or anti-Semitism. In areas where both practices are prevalent (especially in certain communities in Israel), one who can light outside in a manner that does not generate significant doubts may prefer to do so, but he should not feel obligated to change from his family tradition .