David Lewis (born David Losz; June 23 or October 1909 – May 23, 1981) was a Canadian labour lawyer and social democratic politician. He was national secretary of the Co-operative Commonwealth Federation (CCF) from 1936 to 1950 and one of the key architects of the New Democratic Party (NDP) in 1961. In 1962, he was elected as the Member of Parliament (MP), in the House of Commons of Canada, for York South. While an MP, he was elected the NDP's national leader and served from 1971 until 1975.
Lewis's politics were heavily influenced by the Jewish Labour Bund, which contributed to his support of parliamentary democracy. He was an avowed anti-communist, and while a Rhodes Scholar prevented communist domination of the Oxford University Labour Club. In Canada, he played a major role in removing communist influence from the labour movement.
In the CCF, he took the role of disciplinarian and dealt with internal organizational problems. He helped draft the Winnipeg Declaration, which moderated the CCF's economic policies to include acceptance of capitalism, albeit subject to stringent government regulation. As the United Steelworkers of America (USW)'s legal counsel in Canada, he helped them take over the International Union of Mine, Mill, and Smelter Workers (Mine-Mill). His involvement with the USW also led to a central role in the creation of the Canadian Labour Congress in 1956.
The Lewis family has been active in socialist politics since the turn of the twentieth century, starting with David Lewis's father's involvement in the Bund in Russia, continuing with David, and followed by his eldest son, Stephen Lewis, who led the Ontario NDP from 1970 until 1978. When David was elected the NDP's national leader in 1971, he and Stephen became one of the first father-and-son teams to head Canadian political parties simultaneously. After his defeat in the 1974 federal election, he stepped down as leader and retired from politics. He spent his last years as a university professor at Carleton University and as a travel correspondent for the Toronto Star. In retirement, he was named to the Order of Canada for his political service. After suffering from cancer for a long time, he died in Ottawa in 1981. In 2026, his grandson Avi Lewis was elected leader of the federal NDP.
Lewis was born David Losz in the Russian Empire sometime after Svisloch's first snowfall in October 1909 to Moishe Losz and his wife Rose (née Lazarovitch). His official birth date of June 23 was the one he gave the immigration officer when he arrived in Canada. Lewis's political activism began in the shtetl he lived in until 1921. Svisloch was located in the Pale of Settlement, the westernmost region of the Russian Empire, in what is now Belarus. After World War I, it became a Polish border town, occasionally occupied by the Soviet Union during the Polish-Soviet War of the early 1920s. Jewish people were in the majority, numbering 3,500 out of Svisloch's 4,500 residents. Unlike many of the other shtetls in the Pale, it had an industrial economy based on tanning. Its semi-urban industrial population was receptive to social democratic politics and the labour movement, as embodied by the Jewish Labour Bund.
Moishe Losz was Svisloch's Bund Chairman. The Bund was an outlawed socialist party that called for overthrowing the Tsar, equality for all, and national rights for the Jewish community; it functioned both as a political party and labour movement. Lewis spent his formative years immersed in its culture and philosophy. The Bund's membership, although mostly ethnically Jewish, was secular humanist in practice.
Moishe and David were influenced by the Bund's political pragmatism, embodied in its maxim that "It is better to go along with the masses in a not totally correct direction than to separate oneself from them and remain a purist." David would bring this philosophy to the Co-operative Commonwealth Federation (CCF) and New Democratic Party (NDP); in clashes between the parties' "ideological missionaries and the power pragmatists when internal debates raged about policy or action", he was in the latter camp.
When the Russian Civil War and the Polish-Soviet War were at their fiercest, in the summer of 1920, Poland invaded, and the Red Russian Bolshevik army counter-attacked. The Bolsheviks reached the Svisloch border in July 1920. Moishe Losz openly opposed the Bolsheviks and would later be jailed by them for his opposition. When the Polish army recaptured Svisloch on August 25, 1920, they executed five Jewish citizens as "spies". Unsafe under either regime and with his family's future prospects bleak, Moishe left for Canada in May 1921, to work in his brother-in-law's Montreal clothing factory. By August, he saved enough money to send for his family, including David and his siblings, Charlie and Doris. In Canada, Moishe anglicized his name to Morris Lewis
David Lewis was a secular Jew, as was Moishe. However, his maternal grandfather, Usher Lazarovitch, was religious and, in the brief period between May and August 1921 before David emigrated, gave his grandson the only real religious training he would ever receive. David did not actively take part in a religious service again until his granddaughter Ilana's Bat Mitzvah in the late 1970s. In practice, the Lewis family, including David, his wife Sophie, and their children Janet, Nina, Stephen, and Michael, were atheists.
The family came to Canada by boat and landed in Halifax, Nova Scotia, in Autumn 1921. They then went by rail to Montreal to meet Moishe Lewis. David Lewis was a native Yiddish speaker and understood very little English at the time. He first improved his English by buying a copy of Charles Dickens' novel The Old Curiosity Shop and a Yiddish-English dictionary. A Welsh teacher at Fairmount Public School, where Lewis was a student, helped him learn English and passed on his Welsh accent.
Lewis entered Baron Byng High School in September 1924. He soon became friends with A.M. (Abe) Klein, who became one of Canada's leading poets. He also met Irving Layton, another future prominent Canadian writer, to whom he acted as a political mentor. Baron Byng High School was predominantly Jewish because it was in the heart of Montreal's non-affluent Jewish community, and was ghetto-like because Jews were forbidden from attending many high schools.
In high school, besides poets, Lewis met Sophie Carson, who eventually became his wife. Klein, their mutual friend, introduced them. Carson came from a religious Jewish family. Her father did not approve of Lewis because he was a recent immigrant to Canada; in Carson's father's opinion, Lewis had little to no possibility of success.
After high school, Lewis spent five years at McGill University in Montreal: four in arts and one in law. While there, he helped found the Montreal branch of the Young People's Socialist League. He gave lectures sponsored by this anti-communist socialist club, and was its nominal leader. One of his favourite professors was Canadian humorist and noted Conservative party proponent, Stephen Leacock, whom Lewis liked more for his personality than for his academic discipline of economics.
In his third year, Lewis founded The McGilliad campus magazine. It published many of his anti-communist views, though the December 1930 issue included an article he wrote expressing his approval of the Russian Revolution and calling for a greater understanding of the Soviet Union; throughout his career, he would attack communism, but would always have sympathy for the 1917 revolutionaries. Also at McGill, Lewis met and worked with prominent Canadian socialists like F. R. Scott, Eugene Forsey, J. King Gordon, and Frank Underhill. He would work with all of them again in the 1940s and 50s in the CCF.
With Scott's encouragement, Lewis applied for a Rhodes Scholarship during his first year at law school. The interviews for the Quebec representative were conducted in Montreal. The examining board included the then-president of the Canadian Pacific Railway (CPR), Sir Edward Beatty. In response to a question about what he would do if he became prime minister, Lewis stated that he would nationalize the CPR. Despite this answer and his socialist views in general, his responses to the board's cross-examination satisfied them that he was not a communist, and they awarded him the scholarship.