At a meeting some years ago a colleague, a gifted caricaturist, drew a sketch of Bent and entitled it "Bent Christiansen: a nice man". While saying nothing at the time, Bent told me later of his annoyance. "I am not a 'nice' man who smiles sweetly andagrees with everyone: I have a will of my own and will not be swayed." Appearances could be deceptive: Bent Christiansen was always kindly, gracious and a most agreeable companion. Yet his great integrity led him to be intolerant of injustice, of those who were rude, self-seeking, inefficient and not disposed to think, and of those who peddled simple solutions to complex problems. He himself was driven by two great aims: to remove social injustices and to give more students competence in, and an appreciation of, mathematics through improved teaching methods.
He was to achieve much in both these areas. Bent's "background" was that of the "old-style" mathematics educator: he taught and then progressed into teacher-- training. But in the 1960s mathematics education was entering into a new phase. He was greatly influenced through attendance at the Arlon (Belgian) seminars and contact with such educators as Lucienne Felix, Willy Servais and Georges Papy (whose rudeness, however, appalled him) and began to incorporate some of their ideas into his teaching and writing in Denmark. By 1969 his reputation was such that he was invited to be a plenary speaker at the First International Congress on Mathematics Education (Lyons).
The next fifteen or so years saw Bent's greatest contributions to mathematics education. Initially this was through the two international bodies UNESCO and ICMI. Bent became UNESCO's programme specialist in 1972, a time when UNESCO was a force in education. Already Bent had demonstrated his wish to serve the developing countries by acting as a UNESCO-expert in Liberia in the late 1950s. Particularly memorable initiatives in this period were the Conference on Language and Mathematics - a topic of crucial interest to developing countries (Nairobi 1974) and UNESCO's New Trends in School Mathematics (Volume 4) (1979), which was planned in conjunction with ICME 3 (Karlsruhe, 1976).
Bent was to join the Executive Committee of ICMI as its Vice-President in 1975 and served in that post for twelve years. By 1980 it appeared that Bent might well become ICMI's next President, the first mathematics educator to hold that post since ICMI had been a sub-commission of the International Mathematical Union, and only the second since the Commission was founded (following D.E. Smith 1928-31). But this was a period in which ICMI was in disarray and in the end it was the mathematician, Jean-Pierre Kahane, whom IMU asked to be President and to restore credence to ICMI. Bent was disappointed - and not only for personal reasons - but it was entirely in character that he continued as Vice-President under Kahane, working as assiduously as ever to enhance ICMI's standing and work, and speedily and readily acknowledged the outstanding qualities which Kahane brought to the post.
By this time, however, Bent had begun to be involved with other international activities. One, in which Michael Otte and I collaborated, was the BACOMET Project (Basic Components of Mathematics Education for Teachers, 1978-). An outcome of this work, Perspectives on Mathematics Education (1986), possibly helped make Bent's name better known to younger readers internationally. This initiative again provides evidence of Bent's keen interest always to apply the results of research to the one specific goal: the improvement of teaching and learning. This aim also led him to instigate the formation of an international group seeking "systematic co-operation between theory and practice in mathematics education". In this period his influence was exerted much more through leadership and his part in discussions rather than through his writings. He would not have been happy in a 1990s North American or English Education Department. Reading, thinking, discussing, and then translating the results into classroom practice were always rated more highly by him than churning out papers. Moreover, he never established a production line for Ph D students. But he was particularly, and rightly, proud of his association with Stieg Mellin-Olsen, Mogens Niss and Ole Skovsmose (who was Bent's research student). All three clearly show (or alas, showed, for Stieg was to predecease Bent) the imprint of Bent's guidance.
It is possible that many readers of this obituary will know little about Bent, for it is some years since he was at the peak of his powers. Even then, many outside Europe would not have had an opportunity to appreciate his impact on the thinking of others and on the way in which UNESCO and ICMI acted and developed. Yet there can be few mathematics educators who cannot have been affected in some way by Bent's industry, drive and thought and we must all be grateful for his legacy.
As demonstrated above, nobody is better able to write an appreciation of Bent Christiansen and his work for mathematics education at an international level than Geoffrey Howson. In my capacity as a compatriot of Bent's, I shall, in what follows, add some words about Bent and his accomplishments in a Danish context.
Bent Christiansen was born on the 7th May 1921. After having completed, in 1944, his Candidate's (extended Master's) degree in mathematics at the University of Copenhagen, he became a teacher of mathematics at the upper secondary level ("gymnasium") in Holte, a northern suburb of Copenhagen, where he taught until 1957. Already in 1949 he was concurrently working at the Emdrupborg Teacher Training College where he stayed until 1960. At about that time the Royal Danish School of Education was being reconstituted, and Bent Christiansen was appointed its first Professor of Mathematics in 1960. He retired from his professorship, at the age of 70, in 1991.
Bent was a legend in mathematics education in Denmark and the Nordic countries. His impact on the development of the teaching and learning of mathematics in primary and lower secondary education and in teacher training can hardly be overestimated. He wrote text books and books on mathematics education, especially the very influential 'Goals and means in basic mathematics education' ('Maal og midler i den elementaere matematikundervisning', 1967). He gave inumerable in-service courses and invited lectures at meetings and conferences. Naturally, he also served on hosts of national committees, including the Danish National Sub-Commission of ICMI (1961-72). All this earned him a reputation as a charismatic, enthusiastic and extremely energetic mentor for generations of mathematics teachers, teacher trainers and colleagues. In addition to being a protagonist in curriculum development in Denmark, in particular in the 1960s and 1970s, Bent occupied equally significant positions in the Nordic scene. Thus he was a key member of the Nordic Committee for the Modernisation of Mathematics Education, 1960-67. These were the days of the so-called New Mathematics. Bent Christiansen was a leading figure in the introduction of some of the new ideas into Danish (and Nordic) mathematics education, but he always strived to put these ideas into a rich and varied context of mathematical meaning. He was very sad, therefore, to see how less visionary, derivative minds turned these ideas into sterile and stereotyped para-mathematical dry swimming, thus giving rise to (and cause for) skeptical reactions, not of all which were carried by what Bent would consider noble educational concerns. During the 1970s Bent was to develop different views of mathematics education from those of the modern movement, but nothing could make him more furious than representatives of later generations of mathematics educators who thoughtlessly misinterpreted or distrusted the intentions and serious endeavours of himself and his colleagues during the 'modern era'.
During the 1970s, Bent Christiansen transformed himself from a curriculum developer and a teacher trainer to a didactician of mathematics who took a serious interest in all aspects of mathematics education. This gave him ample opportunity to involve his rich and multi-faceted personality in his professional work to an even greater extent than was the case in the first stages of his career. He developed his intensive and extensive interest in human beings and their lives in (not alsways so) democratic society into a creative platform for his own research and development activities. He tirelessly emphasised that mathematics education should not degenerate into a technical discipline of narrow-minded 'know how'. Especially, he saw undue reduction of complexity as perhaps the most fatal trap for mathematics education. Instead, he insisted that we should never forget that mathematics education involves, in an intrinsic manner, human, cultural, social, and political values which have to be taken into account in everything we do in the field. At the same time, he never forgot to emphasise that mathematics as a discipline has hosts of important contributions to offer to human beings who are to master their private, professional and social lives in society.
Bent continued to maintain a vivid and concerned interest in his beloved field, far beyond the age of retirement. The last time I saw him was at a meeting at the end of March of the Danish 'Forum for the Didactics of Mathematics', of which he was, most maturally, an (the) honorary member. I was giving a (critical) lecture on constructivism and Bent attended, despite the frail and evidently very unpleasant condition his long lasting kidney disease had brought him into. Not only did he want to meet and talk to old friends, he was very eager to take part in the subsequent discussion with fresh, thought-provoking and, above all, deeply concerned comments that moved all of us who were present. Bent Christiansen died on the 3rd September 1996. Mathematics education, his family, friends, and colleagues have lost a great humanist.