The eruv is perhaps the most creative, confounding, and contested spatial construct in Judaism. Territorially, it demarcates the urban space within which prohibitions otherwise attached to Sabbath observance for Orthodox Jews become permitted. While virtually imperceptible to the human eye, eruvin (pl.) sanctify what would otherwise be sacrilegious. An eruv thus creates permissive religious space for Jews on Sabbath. Hundreds of cities worldwide, including urban areas across North America, are home to an eruv. Notwithstanding their prevalence and undetectable physical imprint on urban landscapes, the establishment of eruvin has unleashed intense hostility and resistance in some locales. Opposition has typically been mounted by a surprisingly mixed array of critics including non-Jews, non-Orthodox Jews, and dissenting Orthodox Jews. The eruv highlights, in compelling fashion, the spatial challenges of navigating faith, ritual, secularism, and pluralism in contemporary American cities. Seemingly ethereal religious beliefs can occasion radically different perceptions of public space.
Muslim-Jewish relations began with the emergence of Islam in 7th-century Arabia, but contacts between pre-Jewish Israelites and pre-Muslim Arabs had been common for nearly two millennia previously. These interactions inform the earliest relations between Muslims and Jews and serve as precursors to the social, cultural, religious, political, and institutional relations between Muslims and Jews from the 7th century to the present. Areas and periods of particular importance are 7th-century Arabia with first contacts between Jews and the earliest Muslims, 8th–9th-century Middle East with the establishment of legal and social status of Jews in Islam, the 9th to 14th centuries in many parts of the Muslim world with the development of great Jewish intellectual advances under Islamic influence, the subsequent decline of the Muslim world and its negative impact on Jews and other minorities, the period under colonial powers with the rise of national movements and the subsequent transition to independent nation-states that includes the rise of both Jewish and Palestinian nationalisms, and the current status of Muslim-Jewish relations today. Common issues include language production; cultural production including literature, hermeneutics, and systematic thinking; legal developments, political relations, religious commonalities and differences, and economic relations and partnerships.