Ernst Troeltsch (17 February 1865 – 1 February 1923) was a German Protestant theologian and writer on philosophy of religion and philosophy of history, and an influential figure in German thought before 1914. His work was a synthesis of a number of strands, drawing on Albrecht Ritschl, Max Weber's conception of sociology, and the Neo-Kantians of the Baden school.

His The Social Teachings of the Christian Church (two volume edition in translation by Harper Row, 1960) is a seminal work in this area.

While religious thinking in the days of the Weimar Republic moved away from his direction, Troeltsch's work in the sociology of religion remains important.

Ernst Bloch (German pronunciation: [ˈɛʁnst ˈblɔx], July 8, 1885 – August 4, 1977) was a German Marxist philosopher.

Bloch was influenced by Hegel, Marx, and novelist Karl May. Counted also among his influences are apocalyptic and religious thinkers as diverse as gnostics like Valentinus (see "Spirit of Utopia") and Thomas Müntzer (see "Thomas Müntzer als Theologe der Revolution"). He established friendships with Georg Lukács, Bertolt Brecht, Kurt Weill, Walter Benjamin, and Theodor W. Adorno. Bloch's work focuses on the concept that in a humanistic world where oppression and exploitation have been eliminated there will always be a truly revolutionary force.

Bloch was born in Ludwigshafen, the son of a Jewish railway-employee. After studying philosophy, he married Else von Stritzky, daughter of a Baltic brewer in 1913, who died in 1921. His second marriage with Linda Oppenheimer lasted only a few years. His third wife was Karola Piotrowska, a Polish architect, whom he married in 1934 in Vienna. When the Nazis came to power, they had to flee, first into Switzerland, then to Austria, France, Czechoslovakia, and finally the USA. Bloch returned to the GDR in 1949 and obtained a chair in philosophy at Leipzig. When the Berlin Wall was built in 1961, he did not return to the GDR, but went to Tübingen in West Germany, where he received an honorary chair in Philosophy. He died in Tübingen.

Miguel Abensour (born in 1939) is a French philosopher, specializing in political philosophy. He is also an emeritus professor of political philosophy at the Paris Diderot University (Jussieu) and a former president of the Collège international de philosophie.

Miguel Abensour has written for the revues Textures, Libre and Tumultes. Director of the collection « Critique de la politique » (from the publisher Payot & Rivages) since 1974, he was notable in contributing to the reception of the Frankfurt School in France. In his works and numerous articles, he has sought to reconcile democracy, understood as « democracy against the state » with the idea of utopia, conceived from the criticism of Emmanuel Levinas of Martin Buber's idea of interpersonal relations - the I and Thou relationship opposed to the I and It.

He has also published numerous articles on Emmanuel Levinas, Claude Lefort, Saint-Just, utopian socialism (Pierre Leroux, William Morris), Blanqui and members of the Frankfurt School.