Johnston, Joseph (1890–1972), economist and senator, was born 2 August 1890 in Castlecaulfield, Co. Tyrone, one of the eight children and the youngest of the six sons of John Johnston, schoolteacher, and his wife, Mary, née Geddes. He was educated at Dungannon Royal School and as a classics student in 1906 entered Trinity College, Dublin, from where he graduated in 1910 with a double moderatorship in classics and ancient history, having been awarded two gold medals and named university student of the year. He then went to Lincoln College, Oxford, where he took a second BA degree (in litterae humaniores) which was conferred in October 1912, before he returned to Trinity College, Dublin, where he successfully took the fellowship examination and graduated MA in 1913. In 1914–15 he travelled abroad as an Albert Khan travelling fellow, studying economic and social phenomena in India, America, Java, China and Japan. He lectured in ancient history at Trinity College, Dublin (1916–32), and was a Barrington lecturer (1922–32) and a member of the agricultural commission (1923–4). He was adviser on regional economics to the Free State side in the boundary commission negotiations of 1925, and was appointed to the prices commission (1926–7). He also worked as a Rockefeller fellow for economic research in Europe in 1928–9 and lectured at the School of Commerce, Rathmines (1925–32).
In 1932 Johnston was appointed lecturer in applied economics at TCD, and was elected to Seanad Éireann in 1938 as an independent for Dublin University. In 1939 Trinity College established a chair of applied economics for him. He remained a senator until his defeat in the 1943 general election but was appointed by the government to the post-emergency agricultural commission (1942–5) and was returned to the seanad in 1944–8. He had a long-standing association with the Statistical and Social Inquiry Society of Ireland, through his work as a Barrington lecturer, and was president of this society in 1950–51. In 1951 Éamon de Valera (qv) appointed him to the seanad (1951–4) on the taoiseach's panel. In 1970 he gained a D.Litt. from TCD for his work on Bishop George Berkeley (qv), which was published as Bishop Berkeley's Querist in historical perspective (Dundalk 1970).
Johnston was a prolific author whose best-known book was Civil war in Ulster (first published in 1913), a contemporary polemic directed at Sir Edward Carson (qv) and tory leaders for their part in the Larne gun-running episode, and a work that clearly identified him as one of a small number of relatively well-known Ulster protestant advocates of home rule for Ireland and eventual dominion status. Among his best-known economic studies were The nemesis of economic nationalism (1934), Irish agriculture in transition (1951) and Why Ireland needs the common market (1962).
Johnston's work as an agricultural economist was especially important for what was a substantially agrarian economy, not least because he was among the first agricultural economists in the country and was notable for applying his theories through his management of farms in counties Louth and Meath. His appointments to various state bodies dealing with the economy underlined his reputation in this general area. More broadly, he was an outstanding intellectual who was unusual in excelling across two disciplines, namely classics and economics. His principal residences were in Castlecaulfield, Oxford and Dublin. His sister Anne was a founder member of An Óige in the 1930s and a prominent member of Connradh na Gaeilge. After a brief illness, he died in Dublin 26 August 1972. In 1914 he married Clara, a teacher, daughter of Robert Wilson, also a teacher, of Ballymahon, Co. Longford. They had a daughter and a son, Roy, who was science correspondent of the Irish Times and a prominent republican-socialist thinker who strongly influenced the leftward reorientation of Sinn Féin and the IRA under Cathal Goulding (qv) in the 1960s.