Halakha and Minhag

Leah Blum and Aviva Novick ask:

In today's times there seems to be a focus more on minhag haMakom and social Judaism more than halacha. People seem to decide what their minhag is before turning to the sources, and then try to make the sources fit with their shita. Because people make decisions about observance based on social pressures, they often end up stretching halachot. Many people and even poskim seem to have an "agenda" first and then look at the sources. How can halacha work this way?

I think this is a question that both poskim and lay people contend with on a regular basis, and that it's important for us as halakhic Jews to grapple with it. I would just point out that, as I understand it, this is not an issue related exclusively (or even mostly) to "today's times". Both Ashkenazic and Sephardic rabbis have, for many centuries, taken the idea of "ve-hayyitem ba-hem" as an important underpinning of piskei halakha, and this includes looking at minhag ha-makom and deriving certain aspects of halakha from it. In fact, I think that the significance placed on minhag is considered a hallmark of medieval Ashkenazic Jewish culture.

One source for this is the writings of the late, great Jewish historican Jacob Katz (and there are many others). Furthermore, Rav Haym Soloveitchik has a well-known article that discusses the textual focus of piskei halakha, as opposed to looking largely at minhag, as a particularly *modern* phenomenon (see the bibliographic information for his article in my "list" on this blog).

Of course, the ultimate arbiter of which aspects of minhag ha-makom are given the imprimatur of a p'sak, are rejected completely, or are modified to fit in better with the halakha as it exists has always been someone who is widely accepted by the community as a posek. I'm not sure if this answers the question of "how can halakha work this way", but I do think it's important to know that halakha has long worked this way.