FROM QUERIES RECEIVED over the years about ‘Religious Law and Change’, it is clear that I should have prefaced that article with a distinction that Jacob Katz used to make between two terms: minhag and nohag. These may be roughly translated as ‘custom’ and ‘customary practice’; better yet, ‘custom’ and ‘habitual practice’. The exact terminology isn't significant; the different concepts conveyed by these two words are. Custom (minhag) has a recognized threefold place in halakhah. It may adjudicate between two halakhic views, as in ‘The custom of Ashkenaz is to follow Tosafot; that of Sefarad to follow Maimonides’. It may tilt the balance of an issue in which the law is unclear (be-makom she-ha-halakhah rofefet). Finally, it may determine conduct in the interstices of the halakhah, there being no directives in the normative literature on the subject. Much of our daily prayer is custom, and such phrases as ‘in Poland it is customary not to recite av ha-raḥamim on this Sabbath’ or ‘at this point in prayer the Sefardim add …’ abound in the literature. What characterizes minhag, custom, in all these three instances is that the practices described are both legitimate and recognized by their practitioners as part of the religious inheritance of the community. When it comes to local minhag, all Jewish communities are remarkably tenacious in defending their customs and vindicating their religious traditions, and little distinction can be drawn among different Jewish cultures of the Middle Ages, or of the modern period for that matter. Nohag, ‘habitual practice’, on the other hand, refers to conduct that is not viewed as custom, not perceived as part of a conscious religious tradition, but simply the way people of a community have traditionally acted on the assumption that these practices are legitimate, are in accord with the halakhah.

The subject of both this essay and ‘Religious Law and Change’ is nohag. What happens when a received practice is discovered to contravene the halakhah? This question is made even more acute when the matter touches upon something enjoined by the halakhah (issur ve-heter), as consumption of non-kosher foods, in view of the unquestioned rule that neither custom nor habitual practice can allow that which the halakhah clearly forbids.2 It is in its attitude towards habitual practice that Ashkenaz parts company with other Jewish cultures.