JESHUA BEN JUDAH (sometimes erroneously called Joshuaben Judah; his Arabic name was Abū al-Faraj Furqān ibn Asad; second half of the 11th century), Karaite scholar who lived in Jerusalem. A worthy pupil of his distinguished teacher Yūsuf al-*Baṣīr (Joseph ha-Ro'eh), he was regarded by the Karaites as one of the outstanding savants of his century, although in later times his philosophical and exegetical works tended to be neglected. Jeshua's greatest contribution, however, was his decisive opposition to the so-called catenary theory (in Hebrew rikkuv, literally "compounding") of incest, which had the support of the majority of earlier Karaite jurists, from *Anan downward, which severely limited the circle of women whom a Karaite man could lawfully marry. Jeshua was not the first to oppose this theory – his teacher Yūsuf al-Baṣīr is said also to have been an opponent of it, as was an earlier authority, *David b. Boaz (second half of the tenth century). However, Jeshua's tract on the law of incest dealt with it incisively and in great detail, and since it was subsequently translated from its original Arabic into Hebrew (Sefer ha-Yashar (1908); extracts in Leon Nemoy's Karaite Anthology (1952), 127–32; cf. Steinschneider, Arab Lit, 91–94), it remained accessible to later Karaite scholars who knew no Arabic and thus retained its influence upon them. In order to loosen the ever tightening noose fastened by the catenary theory upon the physical survival of the Karaite group, Jeshua established the following principles:
(1) The biblical dictum that man and wife become "one flesh" (Gen. 2:24) does not mean that all close relatives of the wife automatically become equally close to the husband, but merely refers to the couple's mutual affection and intimacy;
(2) The biblical identification of the wife's "nakedness" with the husband's "nakedness" similarly has nothing to do with incest, but merely refers to the husband's duty to guard his wife's chastity, the violation of which is as much an injury to him as to her;
(3) The biblical use of terms like "sister" or "aunt" with reference to distant or adopted relatives is merely figurative;
(4) The forbidden degrees of relationship are those listed in Scripture, their blood relatives, and those derived from them by analogy used only once – piling analogy upon analogy (as was done by the adherents of the catenary theory) is both unlawful and absurd, since it has no definable limit. Jeshua's definition of incest became the rule in later codes of Karaite law, down to and including Elijah *Bashyazi's authoritative code.
Although Karaite limitations on permissible marriages remain more stringent than the Rabbanite ones, Jeshua is responsible for one of the very few radical reforms ever introduced in Karaite jurisprudence. Jeshua's other works comprise an Arabic translation of the Pentateuch with a longer and shorter philosophical commentary, and comments on Genesis and on the Decalogue, extant mostly in fragments. A short Hebrew tract on the law of incest (Iggeret ha-Teshuvah or Teshuvat ha-Ikkar, Eupatoria, 1834) was printed under his name, but his authorship of it seems uncertain. Two philosophical tracts are also ascribed to him. Like his teacher, Jeshua follows in the footsteps of the Muʿtazilite (see *Kalam) school of Arab philosophers. He agrees with al-Baṣīr that certain knowledge of the creation of the world and the existence of God cannot be derived from the Bible alone but must come originally from rational speculation. Like al-Baṣīr he regards as the cornerstone of his religious philosophy the proof that the world was created in time. He also maintains that the Creator is not a "cause," i.e., an impersonal entity which by necessity produces other things from itself, but an "agent," i.e.,
M. Schreiner, Studien ueber Jeschua ben Jehuda (1900); S. Poznański, The Karaite Literary Opponents of Saadiah Gaon (1908), 48–53, 103; Husik, Philosophy, 55–58; Guttmann, Philosophies, 78–81.