Andries Hugo Donald Mac Leod (10 August 1891 – 28 March 1977) was a

Belgian Belgian may refer to: * Something of, or related to, Belgium * Belgians, people from Belgium or of Belgian descent * Languages of Belgium, languages spoken in Belgium, such as Dutch, French, and German *Ancient Belgian language, an extinct language ...

Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used b ...

philosopher and

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...

. Andries Mac Leod was born in

Ledeberg Ledeberg is a submunicipality of the city of Ghent Ghent ( nl, Gent ; french: Gand ; traditional English: Gaunt) is a city and a Municipalities of Belgium, municipality in the Flemish Region of Belgium. It is the capital and largest city of ...

, a suburb of

Ghent Ghent ( nl, Gent ; french: Gand ; traditional English: Gaunt) is a city and a Municipalities of Belgium, municipality in the Flemish Region of Belgium. It is the capital and largest city of the East Flanders province, and the third largest i ...

, as a son of

Julius Mac Leod Julius Mac Leod (19 February 1857 – 3 March 1919), was a Belgian biologist and professor at the University of Ghent. His father was of Scottish descent. Mac Leod was born in Ostend. He was also director of the botanical garden. Julius Mac L ...

, a botanist and professor at

Ghent University Ghent University ( nl, Universiteit Gent, abbreviated as UGent) is a public research university located in Ghent, Belgium. Established before the state of Belgium itself, the university was founded by the Dutch King William I in 1817, whe ...

, and of Fanny Mac Leod born Maertens, who was translator from English into Dutch of two books by

Kropotkin Pyotr Alexeyevich Kropotkin (; russian: link=no, Пётр Алексе́евич Кропо́ткин ; 9 December 1842 – 8 February 1921) was a Russian anarchist, socialist, revolutionary, historian, scientist, philosopher, and activist ...

. While Mac Leod was attending the atheneum in Ghent, he already got interested in philosophy and he was one of the founders of a ''Wijsgerige Kring'' (philosophical circle) there. One of the other members of this circle was

Marcel Minnaert Marcel Gilles Jozef Minnaert (12 February 1893 – 26 October 1970) was a Dutch astronomer of Belgian origin. He was born in Bruges and died in Utrecht. He is notable for his contributions to astronomy and physics and for a popular book on met ...

, with whom he maintained a lifelong friendship. Mac Leod studied mathematics and

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which rel ...

, where he obtained his

doctorate A doctorate (from Latin ''docere'', "to teach"), doctor's degree (from Latin ''doctor'', "teacher"), or doctoral degree is an academic degree awarded by universities and some other educational institutions, derived from the ancient formalism '' ...

in July 1914 by submitting a

thesis A thesis ( : theses), or dissertation (abbreviated diss.), is a document submitted in support of candidature for an academic degree or professional qualification presenting the author's research and findings.International Standard ISO 7144 ...

on a problem in

fluid mechanics Fluid mechanics is the branch of physics concerned with the mechanics of fluids (liquids, gases, and plasmas) and the forces on them. It has applications in a wide range of disciplines, including mechanical, aerospace, civil, chemical and ...

(which appeared later as Mac Leod 1923). Immediately afterwards he travelled for holidays to

Lapland Lapland may refer to: Places *Lapland or Sápmi, an ethno-cultural region stretching over northern Fennoscandia (parts of Norway, Sweden, Finland, and Russia) **Lapland (Finland) (''Lappi''/''Lappland''), a Finnish region ***Lapland (former pro ...

in Sweden. There he learnt that the German army had invaded Belgium on 4 August 1914. He decided to stay in Sweden. He got a job in the large mathematical library of

Gösta Mittag-Leffler Magnus Gustaf "Gösta" Mittag-Leffler (16 March 1846 – 7 July 1927) was a Swedish mathematician. His mathematical contributions are connected chiefly with the theory of functions, which today is called complex analysis. Biography Mittag-Leffle ...

Djursholm Djursholm () is one of four suburban districts in, and the seat of Danderyd Municipality, Stockholm County, Sweden. Djursholm is included in the multi-municipal Stockholm urban area. Djursholm is divided into a number of different areas: Djurshol ...

near Stockholm. He also attended the seminars of the philosopher

Adolph Phalén Adolf (also spelt Adolph or Adolphe, Adolfo and when Latinised Adolphus) is a given name used in German-speaking countries, Scandinavia, the Netherlands and Flanders, France, Italy, Spain, Portugal, Latin America and to a lesser extent in var ...

Uppsala University Uppsala University ( sv, Uppsala universitet) is a public research university in Uppsala, Sweden. Founded in 1477, it is the oldest university in Sweden and the Nordic countries still in operation. The university rose to significance durin ...

. He was deeply impressed by Phalén's work. In 1921 Mac Leod returned to Belgium, where he became a high school teacher in mathematics and physics, first in

Diest Diest () is a city and municipality located in the Belgian province of Flemish Brabant. Situated in the northeast of the Hageland region, Diest neighbours the provinces of Antwerp to its North, and Limburg to the East and is situated aroun ...

and later in Ghent. In 1922 he married with Gunhild Sahlén, whom he had met during his stay in Sweden. In that year also his first book appeared, an introduction to

non-Euclidean geometry In mathematics, non-Euclidean geometry consists of two geometries based on axioms closely related to those that specify Euclidean geometry. As Euclidean geometry lies at the intersection of metric geometry and affine geometry, non-Euclidean ...

( Mac Leod 1922). In 1927 his first philosophical monograph ( Mac Leod 1927) was published. In February 1939 he moved with his wife to Sweden, where he would stay during the rest of his life, devoting all his time to philosophical research on fundamental

ontological In metaphysics, ontology is the philosophical study of being, as well as related concepts such as existence, becoming, and reality. Ontology addresses questions like how entities are grouped into categories and which of these entities exi ...

and

epistemological Epistemology (; ), or the theory of knowledge, is the branch of philosophy concerned with knowledge. Epistemology is considered a major subfield of philosophy, along with other major subfields such as ethics, logic, and metaphysics. Episte ...

questions. Notably he published two lengthy philosophical monographs in Swedish ( Mac Leod 1960, Mac Leod 1972). In 1960 he got an

honorary doctorate An honorary degree is an academic degree for which a university (or other degree-awarding institution) has waived all of the usual requirements. It is also known by the Latin phrases ''honoris causa'' ("for the sake of the honour") or '' ad ho ...

and a few years later he was honoured with a

Festschrift In academia, a ''Festschrift'' (; plural, ''Festschriften'' ) is a book honoring a respected person, especially an academic, and presented during their lifetime. It generally takes the form of an edited volume, containing contributions from the ...

( Henschen-Dahlquist 1966).

Publications

* * * * *

References

* Buning, L. (1977), "Van en over wijlen Dr. Andries Mac Leod (1891–1977)" (in Dutch), ''Wetenschappelijke tijdingen'' 36, nr. 3: 129–144 * Dahlquist, T. (1980), "Andries Mac Leod (1891–1977) In memoriam", ''Theoria'' 46: 1–4 * Henschen-Dahlquist, A.-M., ed. (1980), "Writings of Andries Mac Leod", ''Theoria'' 46: 5–6 * Henschen-Dahlquist, A.-M., ed. (1966) (in Swedish), ''Analyser och argument. Filosofiska uppsatser tillägnade Andries MacLeod'' (Analyses and arguments. Philosophical essays dedicated to Andries Mac Leod), Uppsala Philosophical Studies, vol. 4, Department of Philosophy, University of Uppsala {{DEFAULTSORT:Mac Leod, Andries Belgian mathematicians 20th-century Belgian philosophers 20th-century Swedish philosophers Ghent University alumni 1891 births 1977 deaths Belgian emigrants Immigrants to Sweden