Mordecai Kaplan was born in Lithuania in 1881, just as the big wave of immigration to America was getting underway. He received a traditional Jewish education in Vilna and immigrated along with his family to America in 1889. His family and personal practices continued to be traditional, but as time went on, Kaplan became increasingly disenchanted with orthodox theology and increasingly interested in non-orthodox approaches to Judaism. He graduated from City College of New York, was ordained at the Jewish Theological Seminary (of the Conservative Movement) and received a master's degree from Columbia University. He served as associate rabbi of Kehillath Jeshurun, an Orthodox synagogue in New York.
In 1909, at the age of 28, Kaplan began to teach at the Jewish Theological Seminary, first heading the Teachers' Institute, then becoming a professor of homiletics and the philosophy of religion.
He helped to create the Young Israel Modern Orthodox movement with Rabbi Israel Friedlander. Due to Kaplan's evolving position on Jewish theology, he was later condemned as a heretic by Young Israel and the rest of Orthodox Judaism, and his name is no longer mentioned in official publications as being one of the movement's founders.
Kaplan was profoundly influenced by the new social science of sociology and recent progress in the physical sciences. He came to see Judaism not as a religion, but as a civilization, characterized not only by beliefs and practices, but by language, culture, literature, ethics, art, history, social organization, symbols, and customs. He promoted the notion of a synagogue-center which offered not only religious prayer services, but study programs, drama, dance, song, sports and exercise.
In 1935, Kaplan wrote Judaism as a Civilization, a book which became the foundation of the new Reconstructionist Movement, and which is still published in paperback. Kaplan taught that we need a reconstruction of the religious foundations of Judaism in light of our understanding that Judaism is a religious civilization. He promoted democracy in the synagogue community and advocated voluntary membership, elected leadership, and respect for the religious opinions of individuals.
Kaplan is also well known for having instituted Bat Mitzvah, when he called his eldest daughter to read the Haftarah on the Shabbat following her 12th birthday. Kaplan continued to study and teach throughout his life until his death in 1983 at the age of 102. His influence is felt far beyond the confines of the Reconstructionist Movement; his ideas found fertile soil in modern, America Jews living in a secular society in the 20th century.
Some key aspects of Kaplan's thinking include:
Judaism is an evolving religious civilization. While our dispersion throughout the world has resulted in some cultural differences, by and large we are united by a common religious civilization and must work toward transcending the differences which would divide us. Our common history is the source of our covenant and what motivates and "commands" us to live Jewishly.
Kaplan did not understand God as a supernatural force in the universe, but rather as the power which makes possible personal salvation, which Kaplan understand as the "worthwhileness of life." "God is the sum of all the animating organizing forces and relationships which are forever making a cosmos out of chaos," Kaplan wrote. God cannot abridge the laws of nature for God is synonymous with natural law.
Prayer is necessary because it helps us become conscious of our conscience, the force within which mediates our relationships and our ability to realize salvation. Moreover, prayer with the community focuses our attention on the community and its needs. And finally, worship offers a release of emotion that can orient us in a positive psychological direction.
Kaplan rejected several traditional Jewish categories, most notably Chosenness. He felt that the term was misunderstood and too often taken as a sign of Jewish superiority, when instead it was conceived as an expression of Jewish obligation to God and humanity. So, too, Kaplan rejected the idea of a personal messiah (that is, that God will send a messiah in the form of a human being). He wrote the "Sabbath Prayer Book" in which he expunged both notions from the prayers. Some Reconstructionist synagogues employ a different version of the Torah blessings to this day, avoiding the phrase "...asher bachar banu mi-kol ha-amim..." (...Who chose us from all the peoples...).
Sources: Rabbi Scheinerman's homepage