Absolute idealism is an ontologically monistic philosophy attributed to G. W. F. Hegel. It is Hegel's account of how being is ultimately comprehensible as an all-inclusive whole. Hegel asserted that in order for the thinking subject (human reason or consciousness) to be able to know its object (the world) at all, there must be in some sense an identity of thought and being. Otherwise, the subject would never have access to the object and we would have no certainty about any of our knowledge of the world. To account for the differences between thought and being, however, as well as the richness and diversity of each, the unity of thought and being cannot be expressed as the abstract identity "A=A". Absolute idealism is the attempt to demonstrate this unity using a new "speculative" philosophical method, which requires new concepts and rules of logic. According to Hegel, the absolute ground of being is essentially a dynamic, historical process of necessity that unfolds by itself in the form of increasingly complex forms of being and of consciousness, ultimately giving rise to all the diversity in the world and in the concepts with which we think and make sense of the world.

Karl Heinrich Marx (5 May 1818 – 14 March 1883) was a German philosopher, economist, sociologist, historian, journalist, and revolutionary socialist. His ideas played a significant role in the development of social science and the socialist political movement. He published various books during his lifetime, with the most notable being The Communist Manifesto (1848) and Capital (1867–1894); some of his works were co-written with his friend and fellow German revolutionary socialist, Friedrich Engels.

Born into a wealthy middle class family in Trier, formerly in Prussian Rhineland now called Rhineland-Palatinate, Marx studied at both the University of Bonn and the University of Berlin, where he became interested in the philosophical ideas of the Young Hegelians. In 1836, he became engaged to Jenny von Westphalen, marrying her in 1843. After his studies, he wrote for a radical newspaper in Cologne, and began to work out his theory of dialectical materialism. Moving to Paris in 1843, he began writing for other radical newspapers. He met Engels in Paris, and the two men worked together on a series of books. Exiled to Brussels, he became a leading figure of the Communist League, before moving back to Cologne, where he founded his own newspaper. In 1849 he was exiled again and moved to London together with his wife and children. In London, where the family was reduced to poverty, Marx continued writing and formulating his theories about the nature of society and how he believed it could be improved, and also campaigned for socialism—he became a significant figure in the International Workingmen's Association.

William James Durant (November 5, 1885 – November 7, 1981) was a prolific American writer, historian, and philosopher. He is best known for The Story of Civilization, 11 volumes written in collaboration with his wife Ariel Durant and published between 1935 and 1975. He was earlier noted for The Story of Philosophy, written in 1926, which one observer described as "a groundbreaking work that helped to popularize philosophy."

He conceived of philosophy as total perspective, or, seeing things "sub specie totius," a phrase inspired by Spinoza's "sub specie aeternitatis." He sought to unify and humanize the great body of historical knowledge, which had grown too voluminous and become fragmented into esoteric specialties, and to vitalize it for contemporary application. Durant was a gifted prose stylist and storyteller who won a large readership in great part because of the nature and excellence of his writing, which, in contrast to formal academic language, is lively, witty, charismatic, colourful, ornate, epigrammatic, in short, "humanized." Max Schuster, co-founder of the publisher Simon & Schuster (which also published Durant's works), and himself an admirer of Durant's writings for their beauty, remarked that Durant's prose "begs to be read aloud."John Little, who founded and heads the Will Durant foundation and has devoted much effort towards popularizing Durant's works in the 21st century, echoes Schuster's admiration for Durant's works in words which Durant himself sometimes used to describe a few of the finest works of Classical Antiquity: "prose so beautiful it rivals poetry."

Peter Albert David Singer (born 6 July 1946) is an Australian philosopher who is the Ira W. DeCamp Professor of Bioethics at Princeton University and Laureate Professor at the Centre for Applied Philosophy and Public Ethics at the University of Melbourne. He specialises in applied ethics and approaches ethical issues from a secular, preference utilitarian perspective.

He has served, on two occasions, as chair of philosophy at Monash University, where he founded its Centre for Human Bioethics. In 1996, he unsuccessfully stood as a Greens candidate for the Australian Senate. In 2004, he was recognised as the Australian Humanist of the Year by the Council of Australian Humanist Societies. He has been voted one of Australia's ten most influential public intellectuals. Singer serves on the Advisory Board of Incentives for Global Health, the NGO formed to develop the Health Impact Fund proposal.

Outside academic circles, Singer is best known for his book Animal Liberation, widely regarded as the touchstone of the animal liberation movement. Not all members of the animal liberation movement share this view, and Singer himself has said the media overstates his status. His views on that and other issues in bioethics have attracted attention and a degree of controversy.

Bryan Edgar Magee (born 12 April 1930) is a noted British broadcaster, politician, poet, and author, best known as a popularizer of philosophy.

Born of working class parents in Hoxton, Magee was close to his father, but had a difficult relationship with his abusive and overbearing mother. An evacuee during World War II, he was educated at Christ's Hospital school on a London County Council scholarship. During this formative period, he developed a keen interest in socialist politics, while during the school holidays he enjoyed listening to political orators at Speakers' Corner, Hyde Park, London as well as regular visits to the theatre and concerts. During his National Service he served in the Army and in the Intelligence Corps seeking possible spies among the refugees crossing the border between Yugoslavia and Austria. After demobilisation he won a scholarship to Keble College, Oxford where he read History as an undergraduate and then Philosophy, Politics and Economics in one year. Friends at Oxford included Robin Day, William Rees-Mogg, Jeremy Thorpe and Michael Heseltine. While at university, Magee was elected president of the Oxford Union. He spent a year studying philosophy at Yale University on a post-graduate fellowship. He is an honorary fellow at Keble College, Oxford.