"Where was God at Auschwitz?" For the eminent philosopher and rabbi, Emil Fackenheim, who has died in Jerusalem aged 87, it was imperative to seek an answer to this most vexing question. Even if there were no rational explanation, at least one could derive moral lessons aplenty.
In the mid-1960s, Fackenheim coined a 614th commandment, not listed in the Hebrew Bible - "not to despair of God and not to despair of man"; as a corollary, he argued that Jewish survival "denied Hitler a posthumous victory". And only a strong Israel, he continued, could prevent Jews vanishing from history.
Such views attracted plaudits from nationalists, accusations of chauvinism from liberals, disquiet from Jews who feared Holocaust memory alone would displace Judaic values, and disappointment from former students lamenting Fackenheim's apparent retreat from intellectual subtlety.
A good-humoured, energetic man with a penchant for Hawaiian shirts, Fackenheim felt critics misconstrued his motives. He saw himself as following in the universalist footsteps of the prophet Isaiah. "There will be true peace in Jerusalem when both Islam and Christianity come to worship there, not in spite of our being there, but because of it," he said in 1995.
Fackenheim was a late convert to Zionism. Born in Halle, eastern Germany, he witnessed the twilight glow of the Haskalah, that extraordinarily fruitful, century-long encounter between Judaism and the Enlightenment. He imbibed post-Hegelianism at Halle University, and enrolled at the Haskalah-oriented Hochschule für die Wissenschaft des Judentums in Berlin. After studying under Dr Leo Baeck, he was ordained a reform rabbi in 1938.
Fackenheim's generation believed "the God of Israel had found a home in Germany". One 17th-century Fackenheim fought in the 30 years' war; Emil's father, Julius, founded the Jewish sports club in Halle to drum Prussian discipline into his community. Young Emil, too, regarded himself as equally German and Jewish.
So it came as a rude awakening when, on November 9 1938 - Kristallnacht - the Nazis demolished synagogues across Germany, including the one in Halle. Fackenheim was sent to Sachsenhausen concentration camp, but released after three months. In 1939, he escaped to Scotland, to be joined by his parents, and studied briefly at Aberdeen University. He was then deported to Canada and interned as an enemy alien for 16 months. His elder brother, who had remained in Germany, died in the Holocaust.
Fackenheim quickly made Canada his home. From 1943 to 1948, he was rabbi at Temple Anshei Shalom in Hamilton, Ontario, took his PhD and joined the philosophy faculty of Toronto University, becoming a full professor in 1960. He also married Rose, a convert to Judaism, and raised four children.
He became a master interpreter of Kant, Hegel and Schelling, reviving subversive biblical and talmudic texts that spoke directly to the existential uncertainties confronting 20th-century humanity. He cherished the "quiet voice of God" over the imposing deity at Sinai; he linked ancient Greek thinkers to the rabbis who wrote midrash, or homiletic discourses on the Bible.
Initially, he avoided analysing the Holocaust; it was obscene to view genocide as divine judgment, he argued. Yet he relented, saying that philosophers had a duty to address supreme evil and "torture and murder that became ends in themselves".
He found solace in the kabbalistic paradigm of tikkun olam - mending a shattered world. Relating small acts of courage and charity in the camps could help humanity salvage shards of goodness and justice, thereby reaffirming a seemingly absent God. He posited triumph over the Nazi "hegemony of death" by recasting Heidegger's concept of transcendence in religious terms.
In 1967, Fackenheim's life changed once more. Before the six-day war, Jews everywhere feared that Israel was facing a second Holocaust, and, notwithstanding Israel's military victory in that conflict, Fackenheim henceforth insisted that the Jewish state could no longer be taken for granted.
In 1984, he moved to Jerusalem to teach at the Hebrew University's institute of contemporary Jewry. Somewhat unwittingly, he found himself dragged into political controversy. He marched against the Oslo peace process, and castigated what he called the newfangled victim-becomes-victimiser argument. Yet he vigorously refuted Israelis who equated Yasser Arafat with Hitler. Paradoxically, he enjoyed more prestige in America and Europe than in his beloved Israel, probably because he never fully mastered Hebrew.
Best known for his seminal book, To Mend The World: Foundations Of Future Jewish Thought (1982), Fackenheim also wrote Metaphysics And Historicity (1961), The Religious Dimension In Hegel's Thought (1968), Encounters Between Judaism And Modern Philosophy (1973) and The God Within: Kant, Schelling, And Historicity (1996).
His four children survive him.
· Emil Ludwig Fackenheim, rabbi and philosopher, born June 22 1916; died September 19 2003