NATHANSON, JOSEPH SAUL (1810–1875), *posek. Nathanson was born in Berezhany, the son of Aryeh Leibush Nathanson of Brody, a wealthy businessman who was also a profound talmudist. In 1825 he married Sarah Idel, the daughter of Isaac Aaron Ettinger, who was also a great scholar and a wealthy man. Nathanson, as was customary in those days, was maintained in his father-in-law's home. When his father-in-law died shortly after his marriage, his mother-in-law administered the business and took care that he would be able to live and study without financial cares, and when she died in 1841, his wife took over the responsibility. In his father-in-law's house Nathanson found a colleague in his brother-in-law, Mordecai Ze'ev *Ettinger. They studied together for several years and compiled a series of halakhic works, but they separated as a result of a difference of opinion which came to a head on the question of the permissibility of machine-baked matzah. The two brothers-in-law were rival candidates for the rabbinate of Lemberg to which Nathanson was appointed in 1857. The same year his wife died, but in 1858 he married a wealthy woman and did not accept a salary.
Nathanson was the outstanding posek and writer of responsa of his generation. Problems reached him from all parts of the world and he corresponded with all the great contemporary scholars. In his works he is revealed principally as an instructor in practical halakhah. He regarded himself as responsible for the condition of halakhah in his time, in succession to such scholars as Akiva *Eger and Moses *Sofer. He was opposed to the method of *pilpul for its own sake, regarding it as suitable only for youths (Divrei Sha'ul, Aggadot, 29b) but not for those destined to be religious teachers. He did not necessarily base his decisions "upon the statements of aḥaronim" (Sho'el u-Meshiv, 2 pt. 3, no. 108), but based his rulings mainly upon the Talmud and the rishonim.
He tended to leniency in his rulings, and took contemporary circumstances into consideration. He was one of those who permitted machine-baked matzah in opposition to the view of Solomon *Kluger. Although Kluger decided that *etrogim from Corfu were invalid because of the fear that they were hybrids, Nathanson permitted them (Yosef Da'at, Kilei Begadim, no. 302). He also regarded the birds called "kibbitzer" hens as permitted according to the dietary laws although other authorities forbade them (Sho'el u-Meshiv, 3 pt. 2, no. 121). Although known for his permissive approach, he sometimes declared things forbidden simply as a precaution (Yosef Da'at, Terefot, 64–65). It was this which prompted
On the other hand he was resolutely opposed to schism, and when Zalman Spitzer, the son-in-law of Moses Sofer, published a proclamation calling on 400 rabbis to sign a ban against the payment of taxes to communities whose leaders were progressives, he declined to sign because it would lead to discord. He also maintained harmonious relations with the preachers of the "temple" (i.e., Reform synagogue), Dr. Simeon Schwabacher and Bernhard Loewenstein.
Nathanson was completely opposed to the hasidic movement and its new customs. As such he upheld the Ashkenazi minhag opposing the custom of reciting *Hallel in the synagogues on Passover eve (Sho'el u-Meshiv, 2 pt. 4, no. 135) and the custom of not donning tefillin during the intermediate days of the festivals (ibid., 2 pt. 3, no. 87). Despite his opposition to Ḥasidism, however, he respected their leaders if they were great scholars and quoted them in his works. While still a youth in the house of his grandfather in Berezhany, he made the acquaintance of the ḥasidic rabbi Abraham David of Buczacz and wrote a commendation for his Da'at Kedoshim (1880). In his own works he quotes Levi Isaac of Berdichev (Divrei Sha'ul on the Pentateuch, passim), and among the other ḥasidic leaders he had great respect for Isaac Meir Alter, author of the Ḥiddushei ha-Rim, and was on friendly terms with Ḥayyim Halberstamm, the author of the Divrei Ḥayyim.
Although mainly occupied with halakhah, Nathanson devoted part of his time to biblical study, and wrote Divrei Sha'ul, on the Pentateuch and the Five *Scrolls. He applied himself to the study of Kabbalah, but like the other great posekim of his generation refrained from quoting it in support of the halakhah (Sho'el u-Meshiv, 2 pt. 3, no. 87). He was also versed in the scientific works of the Middle Ages and applied modern methods in practical halakhic rulings, such as ordering a chemical analysis to determine the presence of an admixture of forbidden matter in food (ibid., 3 pt. 1, no. 377). He lectured to his students twice daily (ibid., 2 pt. 3, no. 101). He did not prepare his lesson in advance, but involved his pupils in the discussions, and his lesson became a workshop for his novellae. Among his distinguished pupils were Ze'ev Wolf Salat, the publisher of his responsa, and Ẓevi Hirsch Ornstein. He supported talmudic scholars and authors, and Solomon Buber testified of him that "without exaggeration there are extant 300 commendations by him," so that he was designated Sar ha-Maskim ("chief approver," a pun on Gen. 40:9).
Besides the works he compiled with his brother-in-law Moses Ze'ev Ettinger, Nathanson wrote a series of works in halakhah and aggadah. His classic work in halakhah is his responsa Sho'el u-Meshiv (1865–90), in six volumes comprising 15 parts. He was also the author of Divrei Sha'ul veha-Sefer Yosef Da'at (1878–79) on the Shulḥan Arukh, Yoreh De'ah, in two parts; Yad Yosef ve-Yad Sha'ul (1851); Hilkhot Nedarim; Shulḥan Arukh (YD 203–35), Beit Sha'ul, on the Mishnah (in the Romm Vilna edition); Divrei Sha'ul (1877), on the aggadot of the Talmud; Divrei Sha'ul (1875), on the Pentateuch and the five scrolls, in two parts; Divrei Sha'ul ve-hu Sefer Ḥelek le-Shivah (1879), on the Naḥalat Shivah of Samuel b. David ha-Levi; Torat Moshe, on the Torat Ḥattat of Moses Isserles (in: Ḥamishah Sefarim Niftaḥim (1859)); novellae glosses on the four parts of the Shulḥan Arukh; Melekh be-Yofyo (1866), a sermon calling to contribute to the Austrian war effort; Avodatha-Leviyyim on the Torat ha-Adam; Divrei Sha'ul ve-hu Sefer Edut bi-Yhosef on the topics of Maimonides' Mishneh Torah and part of the Shulḥan Arukh; and Ẓiyyon vi-Yrushalayim, on the Jerusalem Talmud (in the Zhitomir edition). Many works and articles have remained unpublished.
Der Israelit, 16 (1875), 258; Fuenn, Keneset, 483f.; S. Buber, in: Ha-Maggid, 19 (1875), 83; Anshei Shem (1895), 97–99; S.M. Chones, Toledot ha-Posekim (1910), 277f.; A. Stern, Meliẓei Esh al Ḥodshei Adar (1938), 69b no. 336; M. Leiter, in: Hadorom, 29 (1969), 146–70; 31 (1970), 171–202; A. Bromberg, Ha-Ga'on Rabbi Yosef Sha'ul Nathanson mi-Levov (1960); EG, 4 (1956), 417f.; D. Halachmi, Ḥakhmei Yisrael (1957), 318f.; N. Herskovicz, in: Or ha-Mizraḥ, 20 (1970/71), 63–72.