Arndt, the youngest son of Reverend Johannes Arndt and Luise Pauline Grutzner was born in Bloemfontein on 27 May 1899. He started his education at the Infants’ School and the Normal Practising School in Bloemfontein, progressing to Grey College, where he matriculated.
Following his schooling Arndt proceeded to obtain a BA degree in Mathematics and Economics at the Grey University College (University of the Free State) in 1920. He also studied at Columbia University in New York where he received an MA in Economics for his dissertation ‘Inconvertible paper money in South Africa’ in 1922, and a PhD in 1924 for his thesis ‘Currency development in South Africa’.
In 1925 Arndt returned to South Africa and was appointed Acting Professor of Economics at the Transvaal University (University of Pretoria). He fulfilled this post until 1936 when, due to the reorganisation of the Economics Department, he was assigned the post of Professor of Banking, a post he held until 1942. Arndt also served as the Dean of the Faculty of Commerce and Public Administration from 1926 to 1936 and was therefore a member of the executive committee of the university senate. He also fulfilled the role of chairperson and member of the university’s library committee for a number of years. He continued lecturing until the end on 1946.
After serving on the technical committee on banking legislation in the early 1940’s Arndt was appointed as the first Registrar of Banks in August 1942, and a few months later as Registrar of Building Societies. He played an important role in the development of the system of supervision of banks, building societies and other financial institutions in South Africa. In July 1951 he was appointed as the Deputy Governor of the South African Reserve Bank, a position from which he retired in June 1961.
Although Arndt played a key role in South Africa’s financial development, it was in decimalisation that he took his greatest steps. From 1951 to 1954 he was a member of the subcommittee of the South African Bureau of Standards appointed to investigate the possible decimalisation of the Union of South Africa’s coinage system. He also served on the Decimal Coinage Commission from 1956 to 1958. For the period from July 1959 until December 1963 he served as chairperson of the Decimalisation Board, having been appointed to oversee the introduction of decimal coinage.
Arndt was a founding member of the Economic Society of South Africa, where he served as Vice-President and President for a number of years. He also served on various government bodies like the Public Service Commission in 1926, for which he conducted an inquiry into statistical services in the civil service. In 1933 he was official adviser to the Union’s delegation to the world monetary and economic conference in London, and from 1934-1935 he was a member of the Industrial Legislation Commission. From 1962 to 1965 Arndt was a member of the Commission of inquiry into the Stock Exchange.
Arndt gave written and oral evidence before several commissions like the Select Committee on the Gold Standard in 1932, The Co-operative Societies and Agricultural Credit Commission in 1933, the Select Committee on the Insurance Bill in 1941, the Commission of Inquiry into Company Law in 1947 and the Commission of Inquiry into the Income Tax Act. He was also a member of the South African Academy for Science and Art and a founder of the Academy’s Faculty of Science and Technology.
Following his retirement Arndt became the Director of the Land and Agricultural Bank of South Africa, a post he filled from 1962 to 1973. He wrote numerous books, pamphlets and journal articles on finance, banking and insurance. His major work, ‘Banking and currency development in South Africa, 1652-1927’, became a standard work on the early history of finance and banking in South Africa.
Arndt was honoured for his achievements by being awarded the Havenga Prize by the South African Academy for Science and Art in 1953 and in 1958 he received a Dcom (honoris causa) from the University of Pretoria. In 1962 he also accepted a DeconSc (honoris causa) from the University of the Witwatersrand, and in 1963 an honorary diploma from the University of the Free State.
He died on 3 May 1983 in Pretoria.