Isaac Baer Levinsohn (Yiddish: יצחק בער לעווינזאהן; October 13, 1788 – February 13, 1860), also known as the Ribal (ריב״ל), was a Jewish scholar of Hebrew, a satirist, a writer and Haskalah leader.

At the age of three Levinsohn was sent to the ḥeder, where he soon manifested unusual aptitude for learning; and at nine he composed a Kabbalistic work that elicited the praise of scholars and rabbis.

Among others, he wrote a patriotic poem on the expulsion of the French from the Russian Empire, which was transmitted to the minister of the interior by General Giers, the commandant of the Radzivilov garrison.

Levinsohn himself regarded his verses as mere literary exercises, and did not attempt to print them; the greater part of them was lost.

Excessive study brought on nervous disorders, and Levinsohn journeyed to Brody, then the centre of the Haskalah, in order to consult the local physicians.

Levinsohn's new position brought him into close relations with Nachman Krochmal of Zolkiev, an authority on all questions of rabbinical learning and Jewish custom.

Returning to Kremenetz in the same year, he began his Te'uddah be-Yisrael, a work destined to leave an indelible impression on a whole generation of Ukrainian Jews.

Repairing to Berdychev, he became a private tutor in the family of a wealthy Jew, and, gathering about him a circle of progressive friends, organized a society for the promotion of culture.

Regarding it as his special mission to carry enlightenment to the young generation, he resided successively in Ostrog, Nemirov, and Tulchin.

On his way to the last named place Levinsohn stopped at Kaminka, the estate of Prince Witgenstein, the field-marshal of the Russian Empire.

When the prince heard of Levinsohn's arrival he invited him to his house, assigned him a suite of rooms, and kept him there through the entire summer.

Notwithstanding this, he never resigned himself to mental inactivity, and during these long years of suffering he made himself familiar with Arabic, Greek, and Syriac, and studied the classics, political economy, and philosophy.

In the same year the minister of public instruction, Prince Lieven, submitted to Levinsohn thirty-four questions on Jewish religion and history, among them the following: "What is the Talmud?

", "Is it true that the Jews expect to rule the entire world when the Messiah arrives, and that members of other religions will be excluded from participation in the after-life?

At the same time he found himself obliged to exercise great care in the treatment of the subject in order to avoid creating undue antagonism.

Levinsohn presents in his "Bet Yehudah" a wonderfully clear and logical exposition of Jewish religious philosophy.

According to him the Jewish religion may be summed up in two principles of belief: faith in one God, which involves the negation of idol-worship; and love of one's neighbour.

Efes Dammim is written in the form of a dialogue between a patriarch of the Greek Church in Jerusalem, Simias, and the chief rabbi in the Jewish synagogue there.

Other polemical works written by Levinsohn are Aḥiyyah Shiloni ha-Ḥozeh (Leipzig, 1841) and Ta'ar ha-Sofer (Odessa, 1863).

This work, which occupied twelve years, and was continued through sickness and suffering, was not only a defense of Judaism, but also an exposition of the value of traditional law in the Jewish religion, and of the great wisdom and moral force of its expounders and teachers.

Levinsohn left a number of works in manuscript, including Pittuḥe Ḥotam, on the period of the Canticles; Yizre El, miscellaneous essays; Be'er Yitzḥak, correspondence with contemporary scholars; and Eshkol ha-Sofer, letters, poetry, and humorous papers.

Joseph Jacobs and Judah David Eisenstein have suggested that Levinsohn may have been the first Jewish figure to discuss "the modern question of vegetarianism.

"[2] According to Jacobs and Eisenstein, Levinsohn justifies the strictness of the rules of ṭerefah with reference to vegetetarianism, and he attributes the longevity of the generations from Adam to Noah to their vegetarian diet.