Born in
Minsk in the
Russian Empire (today in
Belarus), Kaplan attended a
heder and high school in
Łowicz. He joined the
Socialist Zionist Party in 1905, and was one of the founders of the
Youth of Zion – Renewal movement in 1908, later being elected secretary of its Minsk Region branch in 1912. He also helped found the
Youth of Zion movement in Russia in 1912 and was a member of its central committee. In 1917 he graduated from a Moscow
polytechnic as a building engineer. In 1919 Kaplan was a member of the
Ukrainian delegation to the
Versailles Peace Conference. The following year he
immigrated to
Mandatory Palestine and was involved in merging
Youth of Zion with
Hapoel Hatzair to form
Hitachdut. Following his participation in the Conference of the Zionist Federation in London, he was elected to the
Zionist Executive Committee. Shortly afterwards he was sent to Berlin to run Hitachdut's world office. Kaplan returned to Mandatory Palestine in 1923 and joined the
Histadrut's Office of Public Works. A director of the technical department of the
Tel Aviv municipality between 1923 and 1925, he was elected to Tel Aviv city council in 1925, remaining on the council until 1933. That year he joined the board of the
Jewish Agency for Israel and served as its treasurer until 1948. A member of the
Assembly of Representatives, on 14 May 1948 Kaplan was one of the people to sign the
Israeli declaration of independence, and was immediately appointed Minister of Finance in the
provisional government. He was elected to the
first Knesset as a member of
Mapai, and retained the Finance Ministry post, also becoming
Minister of Trade and Industry in
Ben-Gurion's first government. In the
second government the Trade and Industry portfolio was given to
Yaakov Geri, but Kaplan remained Finance Minister. He retained his seat and portfolio following the
1951 elections, and in June 1952 became the country's first Deputy Prime Minister. However, he died three weeks later. ==Commemoration==