Harold BlackhamMore than anyone else Harold Blackham, who has died aged 105, had a claim to have been the architect of modern humanism. Through his dedicated efforts over three quarters of a century, which included writing, lecturing, activism and administration, Blackham's view that there was a lineage of thinking which led from ancient Greeks, through the Renaissance, the Enlightenment, Victorian science and philosophy and up to 20th century forms of free thought and rationalism, a lineage that was positive and optimistic about human capabilities and human nature and should be called and celebrated as humanism, became the dominant definition within the disparate organisations which make up the British humanist movement. As an honorary associate of the Rationalist Press Association, founder of the British Humanist Association and the International Humanist and Ethical Union, and as a prolific writer and speaker, Blackham has left his mark right across the national and international humanist scene.

Born in the Midlands in 1903 and educated at Birmingham University Blackham, whose father and grandfather had been lay Congregationalist preachers, moved to London in 1933, where his active involvement in organised humanism began. After the Second World War he set out to revive the free thought movement under the banner of "humanism", looking, as he wrote in 1981, to recover "for expression in a modern humanism the full body of the age-old tradition, with its accumulating scientific, social and ethical content." In his development of humanism Blackham wrote many books and articles over almost 70 years, including The Humanist Tradition (Routledge, 1953) and Humanism (Penguin, 1968).

But more important even than his writing was his energetic activism. In Birmingham in the 1920s he had founded a local branch of the League of Nations Union and in 1938 he had helped to organise a World Union of Freethinkers conference in London, which turned out to mark the end of the old free thought movement in the face of Fascism and Communism (he was himself involved with bringing Jewish refugee children from Austria to Britain to escape Nazi persecution). Still thinking internationally after the war, in 1946 he called a London conference of the World Union of Freethinkers to discuss "The Challenge of Humanism". The need, however, was for a new international organisation. Blackham took the lead by working with the ethical organisations in Britain, and also with new humanist organisations around the world. Visiting Holland after the war he met the Dutch philosopher and humanist leader Jaap van Praag, with whom he founded the International Humanist and Ethical Union (IHEU) in 1952. Today, the IHEU is a worldwide union of over 100 organisations in 40 nations which continues to develop Humanism internationally. Blackham served as its secretary from 1952 to 1967 and Julian Huxley became its first president.

Blackham also brought his unifying skills to bear in Britain, where in 1963 his efforts persuaded the disparate Ethical and Rationalist organisations in Britain, including the Rationalist Press association and the Ethical Union, to join forces and form the British Humanist Association (BHA). Blackham became director until his retirement in 1968.

Blackham had a lifelong commitment to education, and moral education in particular. Working with people like Cyril Bibby, Lionel Elvin, Sir Gilbert Flemming and Edward Blishen, he went on make the BHA a significant advocate of moral education and personal development in schools, recognised as such even by the Church of England. He was one of the founders of the Journal of Moral Education, which is still published. Working with Dr James Hemming, his fellow humanist and educationist who died in 2007, Blackham ensured that the humanist voice was a feature of debates over religious, moral and values education throughout the second half of the twentieth century, always prepared to work with faith groups and believers in the interests of finding practical solutions to social problems. To that end he founded the Social Morality Council (now the Norham Foundation), which brought together humanists and eminent religious believers to produce agreed solutions to moral questions affecting society.

On his retirement as director in 1968, after a career that included more than 4000 speaking engagements, the BHA acknowledged Blackham as "the architect of the British and international humanist movements". Throughout his long life dedicated to improving the lot of humanity and offering practical moral guidance to whoever wanted it, Harold Balckham offered an exemplary example of Humanism in action.

Harold John Blackham, humanist, born 31 March 1903; died 23 January 2009