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

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 by ...

philosopher Philosophy ('love of wisdom' in Ancient Greek) is a systematic study of general and fundamental questions concerning topics like existence, reason, knowledge, Value (ethics and social sciences), value, mind, and language. It is a rational an ...

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 sub-municipality of the city of Ghent located in the province of East Flanders, Flemish Region, Belgium. It was a separate municipality until 1977. On 1 January 1977, it was merged Mergers and acquisitions (M&A) are business ...

, a suburb of

Ghent Ghent ( ; ; historically known as ''Gaunt'' in English) is a City status in Belgium, city and a Municipalities of Belgium, municipality in the Flemish Region of Belgium. It is the capital and largest city of the Provinces of Belgium, province ...

, as a son of Julius Mac Leod, a botanist and professor at

Ghent University Ghent University (, abbreviated as UGent) is a Public university, public research university located in Ghent, in the East Flanders province of Belgium. Located in Flanders, Ghent University is the second largest Belgian university, consisting o ...

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

Kropotkin Pyotr Alexeyevich Kropotkin (9 December 1842 – 8 February 1921) was a Russian anarchist and geographer known as a proponent of anarchist communism. Born into an aristocratic land-owning family, Kropotkin attended the Page Corps and later ...

. While Mac Leod was attending the atheneum in Ghent, he already got interested in

philosophy Philosophy ('love of wisdom' in Ancient Greek) is a systematic study of general and fundamental questions concerning topics like existence, reason, knowledge, Value (ethics and social sciences), value, mind, and language. It is a rational an ...

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 Belgian-Dutch astronomer. 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 meteorologic ...

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

mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...

and

physics Physics is the scientific study of matter, its Elementary particle, 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 whi ...

, where he obtained his

doctorate A doctorate (from Latin ''doctor'', meaning "teacher") or doctoral degree is a postgraduate academic degree awarded by universities and some other educational institutions, derived from the ancient formalism '' licentia docendi'' ("licence to teach ...

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: D ...

on a problem in

fluid mechanics Fluid mechanics is the branch of physics concerned with the mechanics of fluids (liquids, gases, and plasma (physics), plasmas) and the forces on them. Originally applied to water (hydromechanics), it found applications in a wide range of discipl ...

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

Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...

. 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 Sweden, Swedish mathematician. His mathematical contributions are connected chiefly with the theory of functions that today is called complex analysis. He founded the pre ...

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: Djursho ...

near

Stockholm Stockholm (; ) is the Capital city, capital and List of urban areas in Sweden by population, most populous city of Sweden, as well as the List of urban areas in the Nordic countries, largest urban area in the Nordic countries. Approximately ...

. 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 with German origins. The name is a compound derived from the Old High German ''Athalwolf'' (or ''Hadulf''), a composition of ''athal'', or ''adal'', meani ...

Uppsala University Uppsala University (UU) () is a public university, public research university in Uppsala, Sweden. Founded in 1477, it is the List of universities in Sweden, oldest university in Sweden and the Nordic countries still in operation. Initially fou ...

. 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 around ...

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 ge ...

( 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 Ontology is the philosophical study of being. It is traditionally understood as the subdiscipline of metaphysics focused on the most general features of reality. As one of the most fundamental concepts, being encompasses all of reality and every ...

and

epistemological Epistemology is the branch of philosophy that examines the nature, origin, and limits of knowledge. Also called "the theory of knowledge", it explores different types of knowledge, such as propositional knowledge about facts, practical knowled ...

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 hon ...

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 h ...

( 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